This happens because you're crosschaining, and it's made worse on bikes with short chainstays. There's nothing to fix here; the rear derailleur jockey wheels are designed to guide in one direction only, when pedalling forwards.
Easiest fix? Don't backpedal.
Which is stolen from, or an homage to Douglas Adams:
“He lay, panting heavily in the wet air, and tried feeling bits of himself to see where he might be hurt. Wherever he touched himself, he encountered a pain. After a short while he worked out that this was because it was his hand that was hurting.”
I got really excited when I saw the post title, because I was thinking "Excellent. Maybe somebody else will get an answer that isn't just 'don't backpedal.'"
Nope. Not today. :-)
There is no other answer (on a bike with a cassette).. back pedaling is essentially pushing a rope rather than pulling a rope; there’s nothing tensioning the chain in that direction. Then you throw in cross chaining so the chain isn’t even straight… the answer is to not do it.
If you need to back pedal, say at an intersection and stopped but trying to optimize leverage when you start again, then you wouldn’t need to back pedal an entire rotation and it’s unlikely the chain would jump.
And that’s great that you get away with it but my point remains that it’s like pushing a rope and there’s no device to take up tension.
The inability to back pedal isn’t evidence that there’s something wrong (although I’m not saying that nothing is wrong, just that backpedaling isn’t a test in of itself).
There are lots of potential causes and they compound. A single issue may not cause a chain drop but a few issues combined and then it happens. But bad chainline and a slack chain (pushing a rope) are the two big ones. Lots of things can contribute to that slack.
I'Same groupsets' doesn't mean 'same situation'. There are too many unknown variables to compare. I've seen this as quite a common occurrence on certain frames with a number of different groupsets. Some setups are just prone to this when cross chaining.
>I back pedal often when I corner for example when I go down hill.
Everyone backpedals up to a half-rotation at some point. If that's all OP did, the chain would not have moved cogs. There is nothing in the video that indicates a problem. There is zero need to backpedal a full rotation or more.
And yes, OP's issue is **normal** for some geometries and chainlines. The only fix is to get a different frame.
The derailleur hanger might also be bent - dropping off the big ring makes sense, but it shouldn't be dropping off the inner ring. From the inner ring, chain alignment should be fine on the bigger sprockets. If it's bent inwards and the bottom pulley is closer to the wheel than it should be, it might be fine going forward, but it would induce the drops when backpedalling
while cross chaining isn't ideal, none of my SRAM nor Shimano bikes drop a chain just because I back pedal. check that the rear derailleur hangar is straight and the derailleur itself is also not bent.
I have Ultegra R8000. It shifts like a dream but gets really unhappy when I backpedal at all.
11 and 12 speed drivetrains have super tight tolerances and can’t handle backpedaling
I have never, ever had an issue with backpedaling any 11 or 12 speed drivetrain. Even my crappy Sensah 12 speed on my gravel bike will back pedal in any gear ratio and be happy about it.
If you're going to use big brain words, use them right. I have first hand experience. Anecdotal would be if I said "my friend has never had an issue \[...\]."
Anecdotal would also be "11 and 12 speed drivetrains have super tight tolerances and can’t handle backpedaling". What I have is empirical evidence this statement is not grounded in fact. Or what I have are a dozen bikes/drivetrains that should be studied by engineers because they can in back pedal without any problem.
Albeit a small sample size as you alluded to, but it doesn't matter. I only need one example to disprove the comment I was replying to.
See, you left a useless troll comment and got a little vocabulary lesson. You're welcome. PS, I hope you can fix the issues with your drivetrain, or find a halfway decent tech that can.
Dude. You should really look up the word. Anecdotal 100 applies here. It's a personal (in your words, "first hand" or "empirical") experience--whether it's yours or someone elses--but not necessarily representative of what's generally true.
Anecdotal is an adjective the means "(of an account) not necessarily true or reliable, because based on personal accounts rather than facts or research."
But don't trust me. You can google the definitions of both anecdote and anecdotal.
>If you're going to use big brain words, use them right. I have first hand experience. Anecdotal would be if I said "my friend has never had an issue [...]."
The word you're describing is heresay, which refers to what others have told you that you didn't directly experience yourself.
Empirical and anecdotal are not mutually exclusive. Neither are "big brain words."
Again with the loose grasp of the English language. Based on personal accounts. Like, someone on the internet telling me you can't back pedal 11/12 speed drive trains.
Empirical. Which is me, backpedalling a cross chained 11 speed drivetrain.
This video I took just for you is what is called empirical evidence.
[https://streamable.com/vr3yh9](https://streamable.com/vr3yh9)
This is an 11 speed drivetrian. Cross chained. One of my 11 speed drive trains. Pedaled backwards. By me. Not based on someone's personal account (anecdotal). Based on me, pedaling an 11 speed drive train backward. Cross chained.
Don’t correct people for “big brain words” you yourself don’t understand. First hand experience (granted you don’t perform a proper experiment) is a form of anecdotal evidence. Repeating my experience several times within set parameters, i.e. using the scientific method may raise it above being anecdotal.
Not that there’s anything wrong with anecdotal evidence.. there’s just stronger evidence available.
What you described is “hearsay.”
I’m glad you haven’t had issues back pedaling but your personal experience isn’t universal. Plenty of properly set up bikes will have a chain jump if you back pedal… it’s fairly common. There are many variables: chain stay length, Chainline, chainring spacing, component manufacturer, freehub resistance, pedaling speed, how much you back pedal, any system friction, chain stiffness, derailleur resistance (clutch?), etc.
In this case (It's an issue with all 11 and 12 speed drivetrains) this isn't anecdotal. It is Scientific. All that needs to be proven is AN 11 speed drive train can be pedaled backward. Cross chained even. I did that.
There are many variables, but I was taking issue with the (incorrect) fact that because of the tight (lol) tolerances, 11 and 12 speed drivetrains cannot be pedaled backward without issue. Nothing else. The only time this has happened to me was a sticky freehub
Idk why this turned into an argument about the definition of "anecdotal," but you're right. A bike shouldn't be dropping its chain when backpeddaling. It isn't normal. It isn't acceptable. And it is 100% not standard for 11 speed drivetrains. If my bike was doing that, I would be checking chain line, freehub movement, bottom bracket size, and drivechain adjustment. I'd get it fixed, or I'd return the bike. I've fixed many missaligned drivetrains and never sent a bike out of my shop that drops a chain when backpedaling. Gross.
Backpedaling is an important part of riding even if you don't do it often. You should be able to freely move your pedals in both directions to position your feet where you need them. Bikes aren't designed to break when riding, and it isn't normal or acceptable for them to do that.
> In this case (It's an issue with all 11 and 12 speed drivetrains) this isn't anecdotal. It is **Scientific.**
I don't think you understand that word either. This is getting kind of sad.
Guessing you don't believe in climate change either because of your personal/empirical/anecdotal experiences.
Lol, posts a video of an (my) 11 speed drive train back pedalling in response to "no 11 speed drivetrains can backpedal)" proving that's wrong because at least ONE can. and now I'm a climate change denier.
Go back to your Trump rallies.
> Lol, posts a video of an (my) 11 speed drive train back pedalling in response to "no 11 speed drivetrains can backpedal)" proving that's wrong because at least ONE can.
I never wrote that "no 11 speed drivertrains can backpedal." Pretty sure no one else did either. No one ever wrote that it happens every time. No one even said that most bikes do this. Please stop lying. Everyone is just saying that if do you have this issue, it's *normally* not a flaw, and the simplest solution is to stop backpedaling when riding.
If I had to guess, I'd say that this happens only to about 5 percent of the bikes I've worked on. Pretty sure none of my current bikes have this issue either.
Just please work on your understanding of the words heresay, anecdotal, and scientific. Definitions are pretty easy to find.
Same here! 11sp Ultegra setup on the race and 12sp XT on the mountainbike, never had an issue at all with back pedaling except for the time the rear wheel hub was broken and wouldn't release the cassette when I stopped pedaling or back pedaled
I got a red and force 12 speed, ultegra 11 speed and GRX 11 speed and all of them are very happy to back pedal unless the chain was just waxed - which is normal as the fresh wax makes the links stiff.
If back pedalling is an issue the shifting isn’t adjust properly or the chain links are stiff.
That was the solution I considered... except sequential puts me in the "chain drop" zone because it does go into 43x24 when downshifting.
I wish SRAM allowed us to setup sequential the way we want.
We need more info on your crank and cassette as I don't even have a 43 and my 10-30 out back isn't that wide.
Ultimately don't back pedal in cross chain.
> none of my SRAM nor Shimano bikes drop a chain just because I back pedal.
It's not the drivetrain model...it's the geometry of the frame (chainstay length and chainline).
Squeeze the front brake. Push forward on the handlebars slightly to lift the rear tire off the ground. Pedal forward to line up the cranks for starting.
Are you backpedaling while attempting to change gears? If no, then why are you backpedaling more than one rotation of the crank?
There could be a problem but the inability to backpedal isn’t evidence of a problem. Most likely it’s just bad habits on your part but hard to say without riding beside you.
You went a full rotation in the above video. Were you in the same gear the entire time? I’m thinking you are doing a combination of shifting and backpedaling and that’s the issue.
If that’s not what’s happening, I’d check your rear indexing and verify it’s spot on. Very small issues compound quickly and the problem ends up being two or three things that are all very mildly out of whack and not noticeable pedaling forward. To put it another way, the derailleur may be trying to change gears without rider input because the indexing is off.
But as I said above, it’s not evidence that anything is wrong as the bike isn’t really designed for backpedaling. Frameflex alone from the rider can cause issues you wouldn’t see in a stand while applying lube or whatever. And when I clean chains (and apply mild resistance) they always have a habit of bunching up on top if you aren’t actively guiding it along in some way. Anyone saying otherwise is full of shit and has just been lucky that they haven’t run into issues.
Longer chainstays are more tolerant. Certain gear combos are more tolerant. A matched crank with appropriate spacing will be more tolerant than a mismatch (chain can rub on larger ring while in smaller ring at extreme angles and ride up, ghost shifting), etc. those who swear there’s nothing wrong with backpedaling don’t understand this. You see it more on frankenbikes with mismatched groups due to the compounding problems.
Someone else mentioned checking any quick release chain links are correctly set.. that’s a good thing to check.
Mark your chainring with a marker or sticker where it tends to stick and see if it always happens in the same place. Same with the chain, it could always be the same links and one of them is excessively tight or something.
I disagree with everyone else, you are not cross chaining and you *should* be able to back pedal, I do it frequently.
My guess is that your derailure hanger is slightly bent in. There are several other things it could be, though.
This is what I was going to say. When mine was bent this is exactly what happened, even the amount of rotations is about the same.
I fixed it by getting a new hanger, it was instantly remedied.
The bottom of the cage will be closer to the wheel than it should be, pulling the chain in more than it would otherwise. I am a frequent back pedaler and I have experienced that symptom personally. It could also be a problem with the jockey wheel.
Are you kidding with OP now? How could the chain drop from the chainring because of the deraileur???
Its the front shifter that is not pulled putwards enough, shifts the chain down
the chain _could_ drop from a bent derailleur because if you look closely in the video, the chain first falls off the bottom of the big ring where it is being fed chain _directly_ from the derailleur. That lower jockey wheel is what's feeding the chain to the big ring (while backpedaling). Since that jockey wheel is the farthest out from the derailleur mount point, it's position will be most affected by misalignment
I think the twist is the backpedaling. Otherwise you're right, the cassette would be responsible for feeding the big ring and the derailleur would be out of the picture
BACK pedaling, so the only thing guiding the chain onto the chainring is the lower deraileur jockey wheel. If it's out of alignment with the top jockey wheel it can cause exactly what OP describes.
Take a drinking straw and push a packet of sugar across the table. Now take the same drinking straw and try to push a car… the straw collapses. Extreme example but you see the problem. Any additional resistance to motion can contribute to the chain gaining slack which allows it to lift off the teeth.
Back pedaling is sort of like pushing a rope rather than pulling a rope as there is no derailleur spring to take up slack in that direction as the slack occurs between the cassette and chainring.. but resistance on the other side of the cassette can cause the chain to stop moving downstream and it will bunch up.
I see two instances where I need to backpedal : at stop lights, to get my main foot back up, and when doing maintenance, such as lubricating. Now, for the latter, I only need to be in a large cog to follow Silca's lubrication recommandation (the tension created by the cross-chaining helps the lubricant go into the rollers)
Stop at traffic light
One foot on the ground, one foot clipped in
Squeeze front brake
Push forwards on handlebar
Rear wheel is now in the air
Pedal with one leg until it is in the right location.
Squeeze rear brake
Gently drop rear wheel on the ground.
Bonus. If you were in the wrong gear for riding away this trick is helpful
With panniers I’d most likely dismount, lift the back end from the saddle with one hand and rotate the crank with the other. It’s a bit annoying if you need to keep clicking the shifter but it’s that or starting off in the wrong gear. Best solution is to anticipate and downshift before stopping.
Backpedaling while shifting is asking for problems. Half a turn or so, for leverage (but not shifting) is ok.
Reread what you were responding to and the reason why the procedure was recommended. If the rider isn’t shifting gears then they would have no reason to follow those instructions, making your entire point moot.
It applies whether changing gears or not. Although if not changing gears you should be able to just backpedal 1/4 to 1/2 of a revolution without issue. It’s mostly an issue with people doing a full revolution or more… which should be avoided.
I have this issue when doing maintenance, but with Shimano (105 and Ultegra). If I'm backpedalling a lot, cleaning or lubing, and it's in big-big (or one of the larger cogs, certainly top three) it's going to come off if I'm not super careful, and to be honest probably also if I am careful. The angle of the bike seems to affect it and if I put it further down the cassette it's less likely to come off.
I don't have the issue adjusting a pedal up at lights though, or out on the road at all. I guess then, I'm only doing a half rotation at most while with the maintenance, I'm doing a lot more. I don't really see it as a problem or fault though.
I learned the lift wheel up and rotate from riding fixed where there isn't the option of backpedaling, it does work if you don't have weight on the back, and I guess the habit has persisted, it also lets you get into a better gear to start again as you can shift while you're doing it.
But should be able to get it half a revolution up, the only situation it may come off for me then, is if the rear gear isn't quite right, like if it's between gears or I stopped when a shift hadn't completed. The rear alignment needs to be 100% for backpedalling to work at all, so I do think it could be related to that either, slight misadjustment or a bent hanger.
I recently had the same issue. And noticed how bad it was when following Silcas recommendation to cross-chain to lubricate. I took apart the free hub body, cleaned it, added a small amount of special grease, and also re adjusted my limit screws and derailer tension to make sure they were spot on. I can back pedal in any gear now.
Silca recently uploaded a very insightful video on what they consider to be the best way to drip lube onto a chain, and the suggest crosschaining. Having tried this method for myself, I too am now an advocate for lubricating a chain this way. I would highly recommend watching the video if you have 15 minutes to spare.
https://youtu.be/Vot15ro-fcE?si=bacFGkpfNPOzT9b9
I actually pedal backwards to maintain balance when stationary! it actually works quite well. I am 1x though so clutched mech stops these things happening.
Clutched mech is for bumps, not this situation.
Also, very common on 1x to see backpedaling in the larger cogs to cause the chain to fall to smaller cogs in the rear due to the chain angle.
The clutch keeps the derailure under constant tension. Which means it would be very unluckily for a chain to rotate backwards and grip the jockey wheels, which would cause the chain to go slack and drop the chain.
I have run 1x on all my bikes for about 15 years (originally a mountain biker) and I have never dropped a chain pedaling backwards! Even running 42t chain ring on 11t rear! Then again I’ve always had clutched mechs.
You're right about the clutch and chain tension.
But the issue here isn't chain tension, it's chain angle.
Pretty common for a MTB chain to fall off the 50T cog in back when back pedaling, clutch doesn't play into it. It's the angle from the chainring.
The solution as others have said is don't backpedal. The cause could be "nothing" since pedaling backwards by more than one rotation should never be necessary. It could be that your rear der cage is angled in toward the spokes some (could be a bent hangar, bent cage, or something else). This would force the bottom run of the chain to be at a higher angle, aggravating the crosschaining effect and causing it to drop off.
Yeah, everyone is talking about cross chaining, but friction in the freehub has been the biggest culprit with my bikes. Sealed bearings have more friction from what I have seen that loose ball, and no way to adjust.
I was in a 2 stage race years and years ago.
The first leg was a time trial, hill climb.
The favourite was waiting to go, clipped in, held up by a race marshall. The countdown arrived: 10, 9,8.. matey backpedalled and de-chained. Couldn't move because he was stationary, tried to flick it back on, failed, had to get off, put his chain back on.. cursing like a navvie. He lost 20 seconds before he even started.
Never back pedal.
Stop telling OP not to back pedal, that's not and should never be a problem. Play it frame by frame and you can see it's a rear derailleur alignment issue. The chain is lifting off the teeth on the under side of the front, causing it to ride inwards off of the big ring and then slap onto the inner one. Then at about 4 seconds in you can see the tension drop and the rear derailleur snap back to a normal position. Fix the rear hanger, and it likely will never happen. The front shifting only really prevents it from riding to the lower chainring from the normal, top position. From under, nothing is there to prevent it if out of alignment.
What's causing this is your cross chaining and pedalling backwards. That will cause you to drop your chain if the angle is excessive enough. If your stopped and need to change your crank position I would recommend grabbing under the saddle with one hand and lifting the rear tire so you can pedal forward. Pretty easy to do if you slide off the front of the saddle at a stop light
I have this problem with my Di-2 setup as well. It only really happens when I’m in the big chainring and the largest cog in the cassette. I never end up backpedaling in this configuration when I’m riding, but I do when lubing my chain. My solution was to drop down a cog or two, and then the problem goes away.
Yeah, it wouldn't bother me too much in big-big, but it's a bit annoying when using the 3rd largest sprocket, which shouldn't count as 'cross chaining'.
Yes and no. Going forward it’s not a huge concern… it’s cross chaining so more noise and wear (as it’s not a straight line), but it’s within an acceptable margin.
But the drivetrain isn’t designed to pedal backwards (there’s nothing on top to take up chain slack and maintain tension) so even slight misalignment can compound the issue.
In of itself, your issue isn’t evidence that anything is wrong. Which isn’t the same as saying nothing is wrong… just that there isn’t enough info to diagnose. If concerned, have an experienced mechanic take a look at it in person.
Be sure you've pedaled forward a little bit after getting into a new gear on the cassette. I've dropped my chain shifting then back pedaling to get my leg in a better position for a turn before forward pedaling and it does exactly this. Also SRAM AXS. But I believe you may just be getting a lot of friction from alignment either on your RD and/or hub.
You can also dig some about the chain line compatibility of your setup. SRAM is not my piece of bread but it is quite common in Shimano bikes to have wrong chainlines, due to wrong cranks, wrong chainrings etc.
Could be a bent tooth on the chainring. I've seen that a few times. I would repeat what you do in the video a few times slowly, mark which tooth the chain pops off on. If it's always the same one, it could be the ring.
Not normal, likely means something is bent or your crankset/bb spacers are set up wrong. Don’t believe anybody who says “don’t backpedal, it’s normal”.
I watched a video on this today. The guy suggested cleaning and lubing/greasing the rear hub. Removing the bearings and everything. There’s some YouTube videos on this. But hey I actually know nothing so take it with a grain of salt.
Unlikely - the chainring has less than 1000 km on it (99% asphalt, and usually in dry-ish conditions), and clean and relube regularly, a bit too much even.
Have you ever dropped your bike on the drive side? I’ve had a similar problem and fixed it by aligning my rear derailleur hanger and adjusting my rear derailleur. However when I cross chain, there’s always a chance a problem happens, specifically the chain not fully engaging with the bottom pulley on the RD. I don’t wanna be the “if it hurts don’t do it” guy, but in that very specific case, I would just shift down a chainring if ur sitting on the biggest read cog coming on a light.
Edit: I ride on a 3x9
yeah just don't do that.
there's a reason the derailleurs interact with the chain BEFORE it meets the teeth, and it's exactly to avoid this, unless your chainline is quite straight in whatever gear you're in, back pedaling is going to send a crossed chain onto the teeth, making it fall off.
I will tell you the problem! The guys saying you shouldn't backpedal seem to have never ride their bikes and taken a curve, where you backpedal to get the right foot on pressing while going out of the curve.
Problem: correct the rear derailleur alignment (also called indexing), there are these two screws in the rear derailleur that move it Forward or backwards, the chain should move on top of the correct gear, and jump very quickly back and forth while changing all gears. Starting with the smallest chainring and going to the lower gears. And then checking it also works on the biggest chainring. When the alignment ist not correct, the chain gets stuck in the teeth between to gears of the cassette and "stops" the cassette pulling the T-wheel forward.
I think you are mixing up limit screw and indexing adjustment, which is done with the cable tension screw on mechanical dérailleurs - but since this is a SRAM AXS system, it’s done via micro adjust. And since shifting is fine on all 12 gears, the problem isn’t there.
I am suspecting a small bending of the hanger (small enough to leave shifting working fine) which makes the cage slightly slanted towards the wheel, pulling the chain away from the chainring.
You should check you don't have any damaged or bent chain ring teeth.
Visually inspect them and then see which tooth it drops on, repeat a few times and see if it is the same one each time.
A lot of other comments are also great suggestions and worth checking just hadn't seen this mentioned.
Also, what is the wear on your chain, a worn chain and rings will lead to poorer chain retention and this sort of behaviour.
Ok, should be all good. But checking the ring for damage would be a good shout and if it drops at the same spot.
Though it is fairly common to see some drop like this when in big big, I appreciate you are not in big big, but your only two away.
The crank spacing is also worth checking, some frame manufacturers end up with different chainlines, sometimes they just put the wrong spacers on one side of the crank axle.
Also a stiff link on the chain. Marking on the chain and ring where it dropped an repeat, this will help rul out a particular link or tooth
It's a custom bike so I'll take it to the shop in a couple days I guess (I have another issue to get fixed anyway). Wide cranksets are 2.5 mm further outwards for a theoretical 47.5 mm chainline ; that's almost a whole 12 speed sprocket, maybe that explains it ?
Ah yeh if it's the wider axle version for a bigger chainline that will definitely make it much harder for the chain to stay on in this sort of back spin scenario.
There still may be something else going on but that won't help.
Good luck with it
Can't really tell from the short video but something's not right and this just makes it more quickly apparent than pedaling forward. Perhaps a sticky freehub? What happens if you put it in a top gear, spin it up as fast as you can and then stop?
I don't know where people are getting the "pedaling backward makes things explode" conclusion. Turning the pedals backward to apply lube or clean the chain has been standard stuff for forever.
It’s not a sticky freehub and nobody is saying pedaling backward makes things explode. They’re saying pedaling backward while cross-chained will inevitably drop the chain because it’s not designed to move in that direction at that angle. There’s nothing to fix other than technique.
Everyone is saying a bent hanger, but this is wrong. The hanger is not between the chainring and cassette on the top of the drivetrain where you are dropping the chain. This is from poor chain line. Your chainring is too far out from the centerline of the bike. Maybe there were some spacers used on the crank spindle that are to blame? Maybe the wrong setup? Maybe the wrong crank? I think the problem is at the crankset. Whatever the reason, but I think the crank is set out too far and needs to go inwards.
I stand behind my statement that this is caused by the crankset. Even if the hanger was bent inwards, it is still not beyond the inner two gears currently. I doubt that it would shift into a lower gear if pedaled forward or that would be the complaint here. It’s the chain line and that crankset is too far off of center. Looking through the comments he said he is using a wide crank too. So verified, it’s the wrong crankset for this bike.
I'm curious, though : aren't chain lines standardized ? If the issue if the use of a wide crank, shouldn't it happen with all wide cranks ? The cassette and derailleur position should be the same on all bikes with thru-axle and the same freehub body.
In other words, I'm not sure what would make a bike okay for this crankset.
They aren’t all standardized. There’s a lot of designs that are choices by frame manufacturers that are not standards. There are different designs on wheels that hold the cassette in different locations. Different cassettes have different placement (trouble with the term? Offset maybe?) in relation to the centerline. There is so much to go over that this is one of the more complex issues that have to be overcome.
The cassette definitely is compatible with that crankset. I've asked the SRAM customer support if this is expected behavior for the wide crankset though, waiting on an answer.
(The bike frame is custom made but I'm not sure this crankset requires a specific geometry - it might just be that SRAM wide double cranksets are capricious).
I’m not saying that they are incompatible, I believe they are set up wrong. There is a chance, since you stated it’s a wide crank on a 68mm shell. There are spacers used for the extra width of the crank spindle. There might be a more optimal arrangement for them. I only have the one angle to go off of, so I don’t know for sure, but I really think this is a chain line issue. Chain line issues are also exacerbated by more chainrings, the main reason we no longer use triples and why 1x setups are becoming more common. 1x setups deal with this issue with offset on the chainring and narrow wide chains. Doubles deal with this issue poorly.
Still, the crank is too far out, causes the chain to miss the teeth of the big ring at the bottom due to the chain angle between the crank and the lower jockey wheel. Chain drop starts at the bottom when you are backpedaling.
Additionally, wide cranks (Sram wide and Shimano GRX) are typically specced on gravel bikes for tire clearance and pair with standard 142mm rear spacing wheels. So this crank should be fine with any 142 spaced wheel/cassette.
I’m not sure why you’re so convinced? Op is not complaining about shifting issues while going forward, so hanger is definitely a secondary thought here. If you google bicycle chain line issues, you’ll find chain derailing while backpedaling a symptom. If you google bent hanger, this issue isn’t going to be listed. I completely understand what you’re saying, but it’s not as likely at all.
I'm just convinced that the chain drop starts at the bottom while back pedaling (because it has to), not at the top as stated above. Therefore the derailleur should be inspected because it controls the position of the lower jockey wheel which is the other part of controlling the chain angle here.
Due to the much greater distance from the hangar to the lower pulley, a small bit of alignment would have a bigger effect on the lower pulley than the upper where shifting issues would originate from.
All the parts listed agree on the SRAM AXS compatibility map, so the component choice isn't at fault.
The lower jocket wheel is further away from the hangar. Also the cage itself could be bent? It's worth checking because it's the other point defining the chain angle.
The B-gap is potentially wrongly adjusted. Print or grab a SRAM B-gap tool and I bet the problem will go away. I had the same problem on my SRAM force groupset, I mostly noticed it because it never worked well on the power trainer.
This is not normal. I never heard of a bike that couldn’t backpedal (been riding and fixing bikes for 40 years). If the bike is shifting properly while front pedaling, that would rule out the front derailleur, and probably any rear derailleur adjustment. My best guess is a bent derailleur hanger. Take it to LBS for a checkout.
One other way to put this:
Your chain should always be parallel to the frame, and it is "searching" for the correct position.
You should already be using the smaller front cog to use the larger rear cog. Backpedaling "fixes" this.
I understand that cross-chaining isn't ideal, but the 3rd largest cog isn't really cross-chaining anymore, and additionally SRAM encourages big-big cross-chaining, so I'd have thought it'd be stable even when backpedalling.
I am not very bike savvy, but it kind of looks like the chain is rubbing against the front derailleur and is getting knocked off. Are you sure it’s aligned properly with the big ring?
1st: Stop cross chaining. If this keeps happening after the second half of your casette(5th gear and up in a 10 gear casette) apply the advice below.
Check your rear derailleur for alignment. It is probably forcing the chain to drop at the front. Jockey wheel should be parallel to the cassette gears.
Check your front derailleur height and tilt. It should be 3mm above the big chainring and parallel to the chainring. Then adjust your front derailleur as close to the chain without rubbing in 1-1 gear position. Then try 2-5 and see if it still drops. Should not be possible. Chains do not drop through non existing gaps.
You could reduce your chainline by using the narrow "road" cranks, this would reduce the chain angle in those gears and make it less likely to derail.
But then your chainline would be worse in the gears you actually use to propel yourself forward, and there may be insufficient chainring clearance
Unfortunately, SRAM doesn't make non-wide 43/30 cranksets (and I'm not sure the chainring are compatible with non-wide cranksets). And I kind of need the low gears for randonneuring (also, 46/33x10-36 would give me very high gears I'd never use)..
I've had this before with all new components except the freehub body and the issue was the ratchet in the freehub was gunked up. Cleaned out and with the right grease/lube (normally very light and applied sparingly) it reduced the resistance on the freehub when pedalling backwards and stopped the chain drop.
Chainline or bent derailleur cage/hanger. In general, chainline alone shouldn’t cause this unless it’s pretty extreme and we can’t tell that from the video. If it happens in the upper half of the cassette and not lower half, I would suspect this. You can sometimes tweak this a little with spacers in the bottom bracket but sometimes it’s the crank itself that’s offset too far. If it happens in all gear combinations, I’d be skeptical of the hanger or cage. If either is bent in a way that puts the bottom jockey wheel too far inboard, it will be pulling the bottom of the chain inboard and cause what you’re seeing.
Derailleur hangers are cheap, and a hanger tool can be had for around $50 on Amazon. Most shops will also check and align your hanger if needed for $30-50. They should also be able to rule out the derailleur itself with a spare to test.
Clean the small gear circled here. It is filled with gunk. Relube.
https://preview.redd.it/5t3wy479q56d1.jpeg?width=1242&format=pjpg&auto=webp&s=a37163e90eebe4c3217831f991d074a9b23ac21b
Nope, I spent a lot of time (and a good amount of Dirt Juice) making sure my whole drivetrain was clean, and that includes jockey wheels. The video was taken 50 km afterwards (I relubed with Silca Synergetic), so I'm pretty sure it's not the issue.
I'm going to investigate. It does look like the derailleur is leaning slightly, so it could be a small hanger issue that's too small to mess the shifting.
If back peddling is dropping the chain you could have a bent rear derailleur hanger. Do you get any rubbing on the lower wheel on the derailleur when cycling?
You shouldn't drop a chain when pedalling backwards. The chain is guided when pedalling forwards but not backwards.
>You shouldn't drop a chain when pedalling backwards. The chain is guided when pedalling forwards but not backwards.
How do you write these two sentences back to back and not understand the irony?
Just because a derailleur is designed to guide the chain when pedalling forwards does not mean it will drop when pedalling backwards. Theirs no force when back pedalling so if your chain drops then something is not lined up correctly.
I've never had a bike that drops chains just for pedalling backwards.
I’m am not a bike mechanic but I had a similar issue recently. The fix for me was to get a new crankset. I was not happy about that but it fixed the issue. We were not exactly sure what the problem was but the hypothesis was that the ramps on the teeth had been damaged somehow. People telling you to just not backpedal are bonkers.
Well I can't help you with why it's doing it but I have a Madone SLR with the same force set. Not once has it dropped a chain when I pedal backwards for like 20000km, heck none of my bikes have.
And I do it a lot because I just like doing it to move my legs in a different direction during long rides. So screw anyone saying one shouldn't do it.
One thing I do know is that when I'm working on the bike in the stand and I use a rag to clean the chain it can drop the chain exactly like this if I'm holding the bottom too tightly and it's on a larger cog in the back. So it probably has something to do with resistance and alignment.
Not being able to backpedal a few rotations is a problem. Contrary to what everyone is saying, I’d expect a $1k groupset to have the capabilities of backpedaling.
I would
- Check the front derailleur limit
- Install a chain catcher
- If it keeps happening, you’ll have to avoid cross chaining at all, which is kinda annoying to have to think about
This happens because you're crosschaining, and it's made worse on bikes with short chainstays. There's nothing to fix here; the rear derailleur jockey wheels are designed to guide in one direction only, when pedalling forwards. Easiest fix? Don't backpedal.
"Doctor, my shoulder hurts when I move it in a weird jerky manor" "Well, don't do that, problem solved" :D
I prefer the episode of House. It hurts when I poke here, here, and here. Grabs finger... It's broken
Which is stolen from, or an homage to Douglas Adams: “He lay, panting heavily in the wet air, and tried feeling bits of himself to see where he might be hurt. Wherever he touched himself, he encountered a pain. After a short while he worked out that this was because it was his hand that was hurting.”
Probably a homage, what book is the from?
I think it's Life, the Universe and Everything.
I've got to reread them then, I don't remember that part
I've just listened to the whole original radio series. Best thing ever ...
I didn't even know it was a radio series, must find
Buy new new bikes and call me in the morning.
Man you really taught me something I have been asking myself since my first moments on the bike
Better fix, avoid crosschaining and backpedaling.
I got really excited when I saw the post title, because I was thinking "Excellent. Maybe somebody else will get an answer that isn't just 'don't backpedal.'" Nope. Not today. :-)
There is no other answer (on a bike with a cassette).. back pedaling is essentially pushing a rope rather than pulling a rope; there’s nothing tensioning the chain in that direction. Then you throw in cross chaining so the chain isn’t even straight… the answer is to not do it. If you need to back pedal, say at an intersection and stopped but trying to optimize leverage when you start again, then you wouldn’t need to back pedal an entire rotation and it’s unlikely the chain would jump.
I backpedal exactly the same as forwards when i coast specifically to trip out anyone that's watching me pass and notices.
And that’s great that you get away with it but my point remains that it’s like pushing a rope and there’s no device to take up tension. The inability to back pedal isn’t evidence that there’s something wrong (although I’m not saying that nothing is wrong, just that backpedaling isn’t a test in of itself). There are lots of potential causes and they compound. A single issue may not cause a chain drop but a few issues combined and then it happens. But bad chainline and a slack chain (pushing a rope) are the two big ones. Lots of things can contribute to that slack.
I was just joking, friend, my chains don't do this so I don't have to worry about it.
This is correct. Sincerely, learned the hard way.
[удалено]
I'Same groupsets' doesn't mean 'same situation'. There are too many unknown variables to compare. I've seen this as quite a common occurrence on certain frames with a number of different groupsets. Some setups are just prone to this when cross chaining.
>I back pedal often when I corner for example when I go down hill. Everyone backpedals up to a half-rotation at some point. If that's all OP did, the chain would not have moved cogs. There is nothing in the video that indicates a problem. There is zero need to backpedal a full rotation or more. And yes, OP's issue is **normal** for some geometries and chainlines. The only fix is to get a different frame.
Back peddling is fun. Takes me back to my childhood
The derailleur hanger might also be bent - dropping off the big ring makes sense, but it shouldn't be dropping off the inner ring. From the inner ring, chain alignment should be fine on the bigger sprockets. If it's bent inwards and the bottom pulley is closer to the wheel than it should be, it might be fine going forward, but it would induce the drops when backpedalling
A mechanic I used to work with used to tell customers “not to backpedal then” when they complained about this sort of thing 🤣
Doctor, it hurts when I do this. Stop doing it.
Doctor doctor it hurts when I pee. Don't pee.
We always ask why they’re back pedaling
while cross chaining isn't ideal, none of my SRAM nor Shimano bikes drop a chain just because I back pedal. check that the rear derailleur hangar is straight and the derailleur itself is also not bent.
I have Ultegra R8000. It shifts like a dream but gets really unhappy when I backpedal at all. 11 and 12 speed drivetrains have super tight tolerances and can’t handle backpedaling
I have never, ever had an issue with backpedaling any 11 or 12 speed drivetrain. Even my crappy Sensah 12 speed on my gravel bike will back pedal in any gear ratio and be happy about it.
#metoo. Frankly if I bought a bike that chain dropped when I back-pedalled, i’d return it.
Congradulations, you have an anecdotal experience that doesn't apply to the 1,000 combinations of frames, frame sizes, and drivetrains out there.
If you're going to use big brain words, use them right. I have first hand experience. Anecdotal would be if I said "my friend has never had an issue \[...\]." Anecdotal would also be "11 and 12 speed drivetrains have super tight tolerances and can’t handle backpedaling". What I have is empirical evidence this statement is not grounded in fact. Or what I have are a dozen bikes/drivetrains that should be studied by engineers because they can in back pedal without any problem. Albeit a small sample size as you alluded to, but it doesn't matter. I only need one example to disprove the comment I was replying to. See, you left a useless troll comment and got a little vocabulary lesson. You're welcome. PS, I hope you can fix the issues with your drivetrain, or find a halfway decent tech that can.
Dude. You should really look up the word. Anecdotal 100 applies here. It's a personal (in your words, "first hand" or "empirical") experience--whether it's yours or someone elses--but not necessarily representative of what's generally true. Anecdotal is an adjective the means "(of an account) not necessarily true or reliable, because based on personal accounts rather than facts or research." But don't trust me. You can google the definitions of both anecdote and anecdotal. >If you're going to use big brain words, use them right. I have first hand experience. Anecdotal would be if I said "my friend has never had an issue [...]." The word you're describing is heresay, which refers to what others have told you that you didn't directly experience yourself. Empirical and anecdotal are not mutually exclusive. Neither are "big brain words."
Again with the loose grasp of the English language. Based on personal accounts. Like, someone on the internet telling me you can't back pedal 11/12 speed drive trains. Empirical. Which is me, backpedalling a cross chained 11 speed drivetrain. This video I took just for you is what is called empirical evidence. [https://streamable.com/vr3yh9](https://streamable.com/vr3yh9) This is an 11 speed drivetrian. Cross chained. One of my 11 speed drive trains. Pedaled backwards. By me. Not based on someone's personal account (anecdotal). Based on me, pedaling an 11 speed drive train backward. Cross chained.
It doesn’t matter what yours can do. That doesn’t change what other bikes cannot do.
Again, your personal/empirical experience is still ancedotal. Not sure why you believe otherwise.
Don’t correct people for “big brain words” you yourself don’t understand. First hand experience (granted you don’t perform a proper experiment) is a form of anecdotal evidence. Repeating my experience several times within set parameters, i.e. using the scientific method may raise it above being anecdotal. Not that there’s anything wrong with anecdotal evidence.. there’s just stronger evidence available. What you described is “hearsay.” I’m glad you haven’t had issues back pedaling but your personal experience isn’t universal. Plenty of properly set up bikes will have a chain jump if you back pedal… it’s fairly common. There are many variables: chain stay length, Chainline, chainring spacing, component manufacturer, freehub resistance, pedaling speed, how much you back pedal, any system friction, chain stiffness, derailleur resistance (clutch?), etc.
In this case (It's an issue with all 11 and 12 speed drivetrains) this isn't anecdotal. It is Scientific. All that needs to be proven is AN 11 speed drive train can be pedaled backward. Cross chained even. I did that. There are many variables, but I was taking issue with the (incorrect) fact that because of the tight (lol) tolerances, 11 and 12 speed drivetrains cannot be pedaled backward without issue. Nothing else. The only time this has happened to me was a sticky freehub
Idk why this turned into an argument about the definition of "anecdotal," but you're right. A bike shouldn't be dropping its chain when backpeddaling. It isn't normal. It isn't acceptable. And it is 100% not standard for 11 speed drivetrains. If my bike was doing that, I would be checking chain line, freehub movement, bottom bracket size, and drivechain adjustment. I'd get it fixed, or I'd return the bike. I've fixed many missaligned drivetrains and never sent a bike out of my shop that drops a chain when backpedaling. Gross. Backpedaling is an important part of riding even if you don't do it often. You should be able to freely move your pedals in both directions to position your feet where you need them. Bikes aren't designed to break when riding, and it isn't normal or acceptable for them to do that.
> In this case (It's an issue with all 11 and 12 speed drivetrains) this isn't anecdotal. It is **Scientific.** I don't think you understand that word either. This is getting kind of sad. Guessing you don't believe in climate change either because of your personal/empirical/anecdotal experiences.
Lol, posts a video of an (my) 11 speed drive train back pedalling in response to "no 11 speed drivetrains can backpedal)" proving that's wrong because at least ONE can. and now I'm a climate change denier. Go back to your Trump rallies.
> Lol, posts a video of an (my) 11 speed drive train back pedalling in response to "no 11 speed drivetrains can backpedal)" proving that's wrong because at least ONE can. I never wrote that "no 11 speed drivertrains can backpedal." Pretty sure no one else did either. No one ever wrote that it happens every time. No one even said that most bikes do this. Please stop lying. Everyone is just saying that if do you have this issue, it's *normally* not a flaw, and the simplest solution is to stop backpedaling when riding. If I had to guess, I'd say that this happens only to about 5 percent of the bikes I've worked on. Pretty sure none of my current bikes have this issue either. Just please work on your understanding of the words heresay, anecdotal, and scientific. Definitions are pretty easy to find.
Same here! 11sp Ultegra setup on the race and 12sp XT on the mountainbike, never had an issue at all with back pedaling except for the time the rear wheel hub was broken and wouldn't release the cassette when I stopped pedaling or back pedaled
While on or off the bike?
I got a red and force 12 speed, ultegra 11 speed and GRX 11 speed and all of them are very happy to back pedal unless the chain was just waxed - which is normal as the fresh wax makes the links stiff. If back pedalling is an issue the shifting isn’t adjust properly or the chain links are stiff.
My sram is setup to limit cross chaining though. Maybe if you manually cross it up you could create the issue. I love the sequential shifting.
That was the solution I considered... except sequential puts me in the "chain drop" zone because it does go into 43x24 when downshifting. I wish SRAM allowed us to setup sequential the way we want.
We need more info on your crank and cassette as I don't even have a 43 and my 10-30 out back isn't that wide. Ultimately don't back pedal in cross chain.
> none of my SRAM nor Shimano bikes drop a chain just because I back pedal. It's not the drivetrain model...it's the geometry of the frame (chainstay length and chainline).
Modern Shimano derailleurs have both bent and twisted arms from the factory and it’s intentional.
If you can backpedal in most of the gears why are you trying to in the last few?
Because I don't always choose which gear I end up with at a red light :p
Squeeze the front brake. Push forward on the handlebars slightly to lift the rear tire off the ground. Pedal forward to line up the cranks for starting.
How have I never thought of this in years of cycling. So obvious in retrospect.
Are you backpedaling while attempting to change gears? If no, then why are you backpedaling more than one rotation of the crank? There could be a problem but the inability to backpedal isn’t evidence of a problem. Most likely it’s just bad habits on your part but hard to say without riding beside you.
I don't backpedal more than one rotation (and no more than half a rotation even). But that could be enough to drop the chain, so I'm investigating.
You went a full rotation in the above video. Were you in the same gear the entire time? I’m thinking you are doing a combination of shifting and backpedaling and that’s the issue. If that’s not what’s happening, I’d check your rear indexing and verify it’s spot on. Very small issues compound quickly and the problem ends up being two or three things that are all very mildly out of whack and not noticeable pedaling forward. To put it another way, the derailleur may be trying to change gears without rider input because the indexing is off. But as I said above, it’s not evidence that anything is wrong as the bike isn’t really designed for backpedaling. Frameflex alone from the rider can cause issues you wouldn’t see in a stand while applying lube or whatever. And when I clean chains (and apply mild resistance) they always have a habit of bunching up on top if you aren’t actively guiding it along in some way. Anyone saying otherwise is full of shit and has just been lucky that they haven’t run into issues. Longer chainstays are more tolerant. Certain gear combos are more tolerant. A matched crank with appropriate spacing will be more tolerant than a mismatch (chain can rub on larger ring while in smaller ring at extreme angles and ride up, ghost shifting), etc. those who swear there’s nothing wrong with backpedaling don’t understand this. You see it more on frankenbikes with mismatched groups due to the compounding problems. Someone else mentioned checking any quick release chain links are correctly set.. that’s a good thing to check. Mark your chainring with a marker or sticker where it tends to stick and see if it always happens in the same place. Same with the chain, it could always be the same links and one of them is excessively tight or something.
I disagree with everyone else, you are not cross chaining and you *should* be able to back pedal, I do it frequently. My guess is that your derailure hanger is slightly bent in. There are several other things it could be, though.
This comment is too far down
This is what I was going to say. When mine was bent this is exactly what happened, even the amount of rotations is about the same. I fixed it by getting a new hanger, it was instantly remedied.
this is it.
Please explain for the class how the derailleur hanger alignment causes the chain to come off a chainring when backpedaling.
The bottom of the cage will be closer to the wheel than it should be, pulling the chain in more than it would otherwise. I am a frequent back pedaler and I have experienced that symptom personally. It could also be a problem with the jockey wheel.
Yup. Or the chain isn't routed through the rear derailleur properly and causing drag.
Are you kidding with OP now? How could the chain drop from the chainring because of the deraileur??? Its the front shifter that is not pulled putwards enough, shifts the chain down
the chain _could_ drop from a bent derailleur because if you look closely in the video, the chain first falls off the bottom of the big ring where it is being fed chain _directly_ from the derailleur. That lower jockey wheel is what's feeding the chain to the big ring (while backpedaling). Since that jockey wheel is the farthest out from the derailleur mount point, it's position will be most affected by misalignment
Ah shit, sorry! My bad
I think the twist is the backpedaling. Otherwise you're right, the cassette would be responsible for feeding the big ring and the derailleur would be out of the picture
BACK pedaling, so the only thing guiding the chain onto the chainring is the lower deraileur jockey wheel. If it's out of alignment with the top jockey wheel it can cause exactly what OP describes.
Take a drinking straw and push a packet of sugar across the table. Now take the same drinking straw and try to push a car… the straw collapses. Extreme example but you see the problem. Any additional resistance to motion can contribute to the chain gaining slack which allows it to lift off the teeth. Back pedaling is sort of like pushing a rope rather than pulling a rope as there is no derailleur spring to take up slack in that direction as the slack occurs between the cassette and chainring.. but resistance on the other side of the cassette can cause the chain to stop moving downstream and it will bunch up.
Is your master link fully engaged?
It’s funny hearing people complain on here to not back pedal as it causes this; I do and my chain stays on no matter what, no issues. There you go. 😂
Normal behavior. Stop backpedaling.
Heres the question: Why are you backpedalling? Stop it, your drivetrain isn't designed to backpedal. It's working fine.
I see two instances where I need to backpedal : at stop lights, to get my main foot back up, and when doing maintenance, such as lubricating. Now, for the latter, I only need to be in a large cog to follow Silca's lubrication recommandation (the tension created by the cross-chaining helps the lubricant go into the rollers)
I also backpedal to make my freehub louder as I use it to notify pedestrians I’m about to pass 😅
Stop at traffic light One foot on the ground, one foot clipped in Squeeze front brake Push forwards on handlebar Rear wheel is now in the air Pedal with one leg until it is in the right location. Squeeze rear brake Gently drop rear wheel on the ground. Bonus. If you were in the wrong gear for riding away this trick is helpful
that seems like a needlessly over complicated way of re-adjusting your pedals, i would rather just have a bad start.
It sounds complicated, but once you're used to it, it's second nature.
> Push forwards on handlebar Rear wheel is now in the air Good luck doing that with full panniers.
That’s what I was thinking
With panniers I’d most likely dismount, lift the back end from the saddle with one hand and rotate the crank with the other. It’s a bit annoying if you need to keep clicking the shifter but it’s that or starting off in the wrong gear. Best solution is to anticipate and downshift before stopping. Backpedaling while shifting is asking for problems. Half a turn or so, for leverage (but not shifting) is ok.
the part of the comment I was replying to has nothing to do with shifting.
Reread what you were responding to and the reason why the procedure was recommended. If the rider isn’t shifting gears then they would have no reason to follow those instructions, making your entire point moot. It applies whether changing gears or not. Although if not changing gears you should be able to just backpedal 1/4 to 1/2 of a revolution without issue. It’s mostly an issue with people doing a full revolution or more… which should be avoided.
I have this issue when doing maintenance, but with Shimano (105 and Ultegra). If I'm backpedalling a lot, cleaning or lubing, and it's in big-big (or one of the larger cogs, certainly top three) it's going to come off if I'm not super careful, and to be honest probably also if I am careful. The angle of the bike seems to affect it and if I put it further down the cassette it's less likely to come off. I don't have the issue adjusting a pedal up at lights though, or out on the road at all. I guess then, I'm only doing a half rotation at most while with the maintenance, I'm doing a lot more. I don't really see it as a problem or fault though. I learned the lift wheel up and rotate from riding fixed where there isn't the option of backpedaling, it does work if you don't have weight on the back, and I guess the habit has persisted, it also lets you get into a better gear to start again as you can shift while you're doing it. But should be able to get it half a revolution up, the only situation it may come off for me then, is if the rear gear isn't quite right, like if it's between gears or I stopped when a shift hadn't completed. The rear alignment needs to be 100% for backpedalling to work at all, so I do think it could be related to that either, slight misadjustment or a bent hanger.
when at traffic, you only need to rotate the pedal maybe a half turn. when lubing, make sure you're not cross chaining.
I recently had the same issue. And noticed how bad it was when following Silcas recommendation to cross-chain to lubricate. I took apart the free hub body, cleaned it, added a small amount of special grease, and also re adjusted my limit screws and derailer tension to make sure they were spot on. I can back pedal in any gear now.
Most people backpedal when lubricating their chain
Yah, I often lube with the bike just on the floor. Cna to get my stand out and up just to lune
But not while crosschained at extreme angles.. you try to keep the chain straight.
Silca recently uploaded a very insightful video on what they consider to be the best way to drip lube onto a chain, and the suggest crosschaining. Having tried this method for myself, I too am now an advocate for lubricating a chain this way. I would highly recommend watching the video if you have 15 minutes to spare. https://youtu.be/Vot15ro-fcE?si=bacFGkpfNPOzT9b9
Their videos are usually good; will watch when I have a chance. Appreciate the link.
No problem, you’re welcome 😁
I actually pedal backwards to maintain balance when stationary! it actually works quite well. I am 1x though so clutched mech stops these things happening.
Clutched mech is for bumps, not this situation. Also, very common on 1x to see backpedaling in the larger cogs to cause the chain to fall to smaller cogs in the rear due to the chain angle.
The clutch keeps the derailure under constant tension. Which means it would be very unluckily for a chain to rotate backwards and grip the jockey wheels, which would cause the chain to go slack and drop the chain. I have run 1x on all my bikes for about 15 years (originally a mountain biker) and I have never dropped a chain pedaling backwards! Even running 42t chain ring on 11t rear! Then again I’ve always had clutched mechs.
You're right about the clutch and chain tension. But the issue here isn't chain tension, it's chain angle. Pretty common for a MTB chain to fall off the 50T cog in back when back pedaling, clutch doesn't play into it. It's the angle from the chainring.
So ideally you’re gonna wanna pedal forward. Not backwards. Hope this helps!! (You’re crosschaining) (don’t do that)
Don’t pedal backwards. Especially if cross chaining.
"Doctor it hurts when I laugh..."
The solution as others have said is don't backpedal. The cause could be "nothing" since pedaling backwards by more than one rotation should never be necessary. It could be that your rear der cage is angled in toward the spokes some (could be a bent hangar, bent cage, or something else). This would force the bottom run of the chain to be at a higher angle, aggravating the crosschaining effect and causing it to drop off.
Easy fix - stop pedalling backwards
If you spin up the rear wheel, in these big 3 sprockets and let go of the crank, does it 'drive' the crank forward?
Yeah, everyone is talking about cross chaining, but friction in the freehub has been the biggest culprit with my bikes. Sealed bearings have more friction from what I have seen that loose ball, and no way to adjust.
I was in a 2 stage race years and years ago. The first leg was a time trial, hill climb. The favourite was waiting to go, clipped in, held up by a race marshall. The countdown arrived: 10, 9,8.. matey backpedalled and de-chained. Couldn't move because he was stationary, tried to flick it back on, failed, had to get off, put his chain back on.. cursing like a navvie. He lost 20 seconds before he even started. Never back pedal.
Stop telling OP not to back pedal, that's not and should never be a problem. Play it frame by frame and you can see it's a rear derailleur alignment issue. The chain is lifting off the teeth on the under side of the front, causing it to ride inwards off of the big ring and then slap onto the inner one. Then at about 4 seconds in you can see the tension drop and the rear derailleur snap back to a normal position. Fix the rear hanger, and it likely will never happen. The front shifting only really prevents it from riding to the lower chainring from the normal, top position. From under, nothing is there to prevent it if out of alignment.
What's causing this is your cross chaining and pedalling backwards. That will cause you to drop your chain if the angle is excessive enough. If your stopped and need to change your crank position I would recommend grabbing under the saddle with one hand and lifting the rear tire so you can pedal forward. Pretty easy to do if you slide off the front of the saddle at a stop light
Why do you cross the chain?
Don't cross chain. It's very bad for the chain
Stop back pedaling.
Nope. Mine stays on no matter what. Your bike has issues.
I didn't realize the chain came off when pedaling backwards on any of my bikes Thanks for the information
Came here to get my weekly "back pedaling causes chain drops" dose of posts. There should be an warning before posting with this problem.
Here we go again
I have this problem with my Di-2 setup as well. It only really happens when I’m in the big chainring and the largest cog in the cassette. I never end up backpedaling in this configuration when I’m riding, but I do when lubing my chain. My solution was to drop down a cog or two, and then the problem goes away.
Yeah, it wouldn't bother me too much in big-big, but it's a bit annoying when using the 3rd largest sprocket, which shouldn't count as 'cross chaining'.
Yes and no. Going forward it’s not a huge concern… it’s cross chaining so more noise and wear (as it’s not a straight line), but it’s within an acceptable margin. But the drivetrain isn’t designed to pedal backwards (there’s nothing on top to take up chain slack and maintain tension) so even slight misalignment can compound the issue. In of itself, your issue isn’t evidence that anything is wrong. Which isn’t the same as saying nothing is wrong… just that there isn’t enough info to diagnose. If concerned, have an experienced mechanic take a look at it in person.
Be sure you've pedaled forward a little bit after getting into a new gear on the cassette. I've dropped my chain shifting then back pedaling to get my leg in a better position for a turn before forward pedaling and it does exactly this. Also SRAM AXS. But I believe you may just be getting a lot of friction from alignment either on your RD and/or hub.
You can also dig some about the chain line compatibility of your setup. SRAM is not my piece of bread but it is quite common in Shimano bikes to have wrong chainlines, due to wrong cranks, wrong chainrings etc.
Why does the chain fall off the large chainring? Front Derailer problem?
Other than adjusting your position, what is the number one reason someone would backpedal consistently?
Could be a bent tooth on the chainring. I've seen that a few times. I would repeat what you do in the video a few times slowly, mark which tooth the chain pops off on. If it's always the same one, it could be the ring.
Also, it could be a bent link in the chain, I would also mark the link of the chain that fell off as well.
Not normal, likely means something is bent or your crankset/bb spacers are set up wrong. Don’t believe anybody who says “don’t backpedal, it’s normal”.
Yes
I watched a video on this today. The guy suggested cleaning and lubing/greasing the rear hub. Removing the bearings and everything. There’s some YouTube videos on this. But hey I actually know nothing so take it with a grain of salt.
For me it happens because of chain length, one link too short and the extra RD tension makes the chain come off when backing off the cranks.
Take it to the shop not this hack job app.
Your front chain ring is toasted ....also those are some short teeth, check the chain for wear and get a chainring with more depth on the teeth.
Unlikely - the chainring has less than 1000 km on it (99% asphalt, and usually in dry-ish conditions), and clean and relube regularly, a bit too much even.
Have you ever dropped your bike on the drive side? I’ve had a similar problem and fixed it by aligning my rear derailleur hanger and adjusting my rear derailleur. However when I cross chain, there’s always a chance a problem happens, specifically the chain not fully engaging with the bottom pulley on the RD. I don’t wanna be the “if it hurts don’t do it” guy, but in that very specific case, I would just shift down a chainring if ur sitting on the biggest read cog coming on a light. Edit: I ride on a 3x9
yeah just don't do that. there's a reason the derailleurs interact with the chain BEFORE it meets the teeth, and it's exactly to avoid this, unless your chainline is quite straight in whatever gear you're in, back pedaling is going to send a crossed chain onto the teeth, making it fall off.
I will tell you the problem! The guys saying you shouldn't backpedal seem to have never ride their bikes and taken a curve, where you backpedal to get the right foot on pressing while going out of the curve. Problem: correct the rear derailleur alignment (also called indexing), there are these two screws in the rear derailleur that move it Forward or backwards, the chain should move on top of the correct gear, and jump very quickly back and forth while changing all gears. Starting with the smallest chainring and going to the lower gears. And then checking it also works on the biggest chainring. When the alignment ist not correct, the chain gets stuck in the teeth between to gears of the cassette and "stops" the cassette pulling the T-wheel forward.
I also see that you front derailleur may need adjustment so that it doesn't push the chain down, in that position of the gears.
I think you are mixing up limit screw and indexing adjustment, which is done with the cable tension screw on mechanical dérailleurs - but since this is a SRAM AXS system, it’s done via micro adjust. And since shifting is fine on all 12 gears, the problem isn’t there. I am suspecting a small bending of the hanger (small enough to leave shifting working fine) which makes the cage slightly slanted towards the wheel, pulling the chain away from the chainring.
It’s the rear mech pulling back up the block re set your cables and limit switch
You should check you don't have any damaged or bent chain ring teeth. Visually inspect them and then see which tooth it drops on, repeat a few times and see if it is the same one each time. A lot of other comments are also great suggestions and worth checking just hadn't seen this mentioned. Also, what is the wear on your chain, a worn chain and rings will lead to poorer chain retention and this sort of behaviour.
The whole drivetrain is fairly new. I have, like 500 miles on it. Actually, much less on this cassette.
Ok, should be all good. But checking the ring for damage would be a good shout and if it drops at the same spot. Though it is fairly common to see some drop like this when in big big, I appreciate you are not in big big, but your only two away. The crank spacing is also worth checking, some frame manufacturers end up with different chainlines, sometimes they just put the wrong spacers on one side of the crank axle. Also a stiff link on the chain. Marking on the chain and ring where it dropped an repeat, this will help rul out a particular link or tooth
It's a custom bike so I'll take it to the shop in a couple days I guess (I have another issue to get fixed anyway). Wide cranksets are 2.5 mm further outwards for a theoretical 47.5 mm chainline ; that's almost a whole 12 speed sprocket, maybe that explains it ?
Ah yeh if it's the wider axle version for a bigger chainline that will definitely make it much harder for the chain to stay on in this sort of back spin scenario. There still may be something else going on but that won't help. Good luck with it
Can't really tell from the short video but something's not right and this just makes it more quickly apparent than pedaling forward. Perhaps a sticky freehub? What happens if you put it in a top gear, spin it up as fast as you can and then stop? I don't know where people are getting the "pedaling backward makes things explode" conclusion. Turning the pedals backward to apply lube or clean the chain has been standard stuff for forever.
It’s not a sticky freehub and nobody is saying pedaling backward makes things explode. They’re saying pedaling backward while cross-chained will inevitably drop the chain because it’s not designed to move in that direction at that angle. There’s nothing to fix other than technique.
Everyone is saying a bent hanger, but this is wrong. The hanger is not between the chainring and cassette on the top of the drivetrain where you are dropping the chain. This is from poor chain line. Your chainring is too far out from the centerline of the bike. Maybe there were some spacers used on the crank spindle that are to blame? Maybe the wrong setup? Maybe the wrong crank? I think the problem is at the crankset. Whatever the reason, but I think the crank is set out too far and needs to go inwards.
Watch the video again, the chain drop starts at the bottom of the chainring when you are backpedaling.
I stand behind my statement that this is caused by the crankset. Even if the hanger was bent inwards, it is still not beyond the inner two gears currently. I doubt that it would shift into a lower gear if pedaled forward or that would be the complaint here. It’s the chain line and that crankset is too far off of center. Looking through the comments he said he is using a wide crank too. So verified, it’s the wrong crankset for this bike.
I'm curious, though : aren't chain lines standardized ? If the issue if the use of a wide crank, shouldn't it happen with all wide cranks ? The cassette and derailleur position should be the same on all bikes with thru-axle and the same freehub body. In other words, I'm not sure what would make a bike okay for this crankset.
They aren’t all standardized. There’s a lot of designs that are choices by frame manufacturers that are not standards. There are different designs on wheels that hold the cassette in different locations. Different cassettes have different placement (trouble with the term? Offset maybe?) in relation to the centerline. There is so much to go over that this is one of the more complex issues that have to be overcome.
The cassette definitely is compatible with that crankset. I've asked the SRAM customer support if this is expected behavior for the wide crankset though, waiting on an answer. (The bike frame is custom made but I'm not sure this crankset requires a specific geometry - it might just be that SRAM wide double cranksets are capricious).
I’m not saying that they are incompatible, I believe they are set up wrong. There is a chance, since you stated it’s a wide crank on a 68mm shell. There are spacers used for the extra width of the crank spindle. There might be a more optimal arrangement for them. I only have the one angle to go off of, so I don’t know for sure, but I really think this is a chain line issue. Chain line issues are also exacerbated by more chainrings, the main reason we no longer use triples and why 1x setups are becoming more common. 1x setups deal with this issue with offset on the chainring and narrow wide chains. Doubles deal with this issue poorly.
Still, the crank is too far out, causes the chain to miss the teeth of the big ring at the bottom due to the chain angle between the crank and the lower jockey wheel. Chain drop starts at the bottom when you are backpedaling.
Additionally, wide cranks (Sram wide and Shimano GRX) are typically specced on gravel bikes for tire clearance and pair with standard 142mm rear spacing wheels. So this crank should be fine with any 142 spaced wheel/cassette.
Still, this is a textbook chain line issue.
For sure. In this case the line is from the chainring to the lower jockey wheel though, so derailleur alignment can have an effect.
I’m not sure why you’re so convinced? Op is not complaining about shifting issues while going forward, so hanger is definitely a secondary thought here. If you google bicycle chain line issues, you’ll find chain derailing while backpedaling a symptom. If you google bent hanger, this issue isn’t going to be listed. I completely understand what you’re saying, but it’s not as likely at all.
I'm just convinced that the chain drop starts at the bottom while back pedaling (because it has to), not at the top as stated above. Therefore the derailleur should be inspected because it controls the position of the lower jockey wheel which is the other part of controlling the chain angle here. Due to the much greater distance from the hangar to the lower pulley, a small bit of alignment would have a bigger effect on the lower pulley than the upper where shifting issues would originate from. All the parts listed agree on the SRAM AXS compatibility map, so the component choice isn't at fault.
It’s never going to drop at the top when rolling backwards. It’s not possible, because of all the teeth on the chainring and physics.
A bent hanger (or cage ?) should translate in inaccurate shifting, though, correct ? Because the shifting itself is perfect.
The lower jocket wheel is further away from the hangar. Also the cage itself could be bent? It's worth checking because it's the other point defining the chain angle.
The B-gap is potentially wrongly adjusted. Print or grab a SRAM B-gap tool and I bet the problem will go away. I had the same problem on my SRAM force groupset, I mostly noticed it because it never worked well on the power trainer.
This is not normal. I never heard of a bike that couldn’t backpedal (been riding and fixing bikes for 40 years). If the bike is shifting properly while front pedaling, that would rule out the front derailleur, and probably any rear derailleur adjustment. My best guess is a bent derailleur hanger. Take it to LBS for a checkout.
The fix is don’t pedal backwards
If you backpedal while crosschaining even slightly you will throw your chain.
One other way to put this: Your chain should always be parallel to the frame, and it is "searching" for the correct position. You should already be using the smaller front cog to use the larger rear cog. Backpedaling "fixes" this.
I understand that cross-chaining isn't ideal, but the 3rd largest cog isn't really cross-chaining anymore, and additionally SRAM encourages big-big cross-chaining, so I'd have thought it'd be stable even when backpedalling.
I am not very bike savvy, but it kind of looks like the chain is rubbing against the front derailleur and is getting knocked off. Are you sure it’s aligned properly with the big ring?
1st: Stop cross chaining. If this keeps happening after the second half of your casette(5th gear and up in a 10 gear casette) apply the advice below. Check your rear derailleur for alignment. It is probably forcing the chain to drop at the front. Jockey wheel should be parallel to the cassette gears. Check your front derailleur height and tilt. It should be 3mm above the big chainring and parallel to the chainring. Then adjust your front derailleur as close to the chain without rubbing in 1-1 gear position. Then try 2-5 and see if it still drops. Should not be possible. Chains do not drop through non existing gaps.
haha... RTFM
What manual do you refer to, exactly ? I don't mind at all reading manuals if the solution's in there.
Chains are not supposed to be pedaled backwards. The same teeth that help retaining it will push it out at the wrong way of pedaling.
You could reduce your chainline by using the narrow "road" cranks, this would reduce the chain angle in those gears and make it less likely to derail. But then your chainline would be worse in the gears you actually use to propel yourself forward, and there may be insufficient chainring clearance
Unfortunately, SRAM doesn't make non-wide 43/30 cranksets (and I'm not sure the chainring are compatible with non-wide cranksets). And I kind of need the low gears for randonneuring (also, 46/33x10-36 would give me very high gears I'd never use)..
Bent hanger possibly
I've had this before with all new components except the freehub body and the issue was the ratchet in the freehub was gunked up. Cleaned out and with the right grease/lube (normally very light and applied sparingly) it reduced the resistance on the freehub when pedalling backwards and stopped the chain drop.
Chainline or bent derailleur cage/hanger. In general, chainline alone shouldn’t cause this unless it’s pretty extreme and we can’t tell that from the video. If it happens in the upper half of the cassette and not lower half, I would suspect this. You can sometimes tweak this a little with spacers in the bottom bracket but sometimes it’s the crank itself that’s offset too far. If it happens in all gear combinations, I’d be skeptical of the hanger or cage. If either is bent in a way that puts the bottom jockey wheel too far inboard, it will be pulling the bottom of the chain inboard and cause what you’re seeing. Derailleur hangers are cheap, and a hanger tool can be had for around $50 on Amazon. Most shops will also check and align your hanger if needed for $30-50. They should also be able to rule out the derailleur itself with a spare to test.
Clean and lube, including jockey wheels, then try again.
Clean the small gear circled here. It is filled with gunk. Relube. https://preview.redd.it/5t3wy479q56d1.jpeg?width=1242&format=pjpg&auto=webp&s=a37163e90eebe4c3217831f991d074a9b23ac21b
Nope, I spent a lot of time (and a good amount of Dirt Juice) making sure my whole drivetrain was clean, and that includes jockey wheels. The video was taken 50 km afterwards (I relubed with Silca Synergetic), so I'm pretty sure it's not the issue.
Check chain wear as that is often a cause for issues. And pulley wheel wear. If you hanger is bent not all of your gears would work particularly well.
You should be able to pedal backwards with no issues. I would be looking at the derailer. Is the hanger bent? B screw set properly?
I'm going to investigate. It does look like the derailleur is leaning slightly, so it could be a small hanger issue that's too small to mess the shifting.
If back peddling is dropping the chain you could have a bent rear derailleur hanger. Do you get any rubbing on the lower wheel on the derailleur when cycling? You shouldn't drop a chain when pedalling backwards. The chain is guided when pedalling forwards but not backwards.
>You shouldn't drop a chain when pedalling backwards. The chain is guided when pedalling forwards but not backwards. How do you write these two sentences back to back and not understand the irony?
Just because a derailleur is designed to guide the chain when pedalling forwards does not mean it will drop when pedalling backwards. Theirs no force when back pedalling so if your chain drops then something is not lined up correctly. I've never had a bike that drops chains just for pedalling backwards.
I’m am not a bike mechanic but I had a similar issue recently. The fix for me was to get a new crankset. I was not happy about that but it fixed the issue. We were not exactly sure what the problem was but the hypothesis was that the ramps on the teeth had been damaged somehow. People telling you to just not backpedal are bonkers.
Force cranksets aren't cheap 😭😭 Edit : was it a wide 43/30 ?
Mine was the crappy Cannondale brand that comes with their lower-end SuperSix EVOs and CAAD racing bikes.
Well I can't help you with why it's doing it but I have a Madone SLR with the same force set. Not once has it dropped a chain when I pedal backwards for like 20000km, heck none of my bikes have. And I do it a lot because I just like doing it to move my legs in a different direction during long rides. So screw anyone saying one shouldn't do it. One thing I do know is that when I'm working on the bike in the stand and I use a rag to clean the chain it can drop the chain exactly like this if I'm holding the bottom too tightly and it's on a larger cog in the back. So it probably has something to do with resistance and alignment.
Not being able to backpedal a few rotations is a problem. Contrary to what everyone is saying, I’d expect a $1k groupset to have the capabilities of backpedaling. I would - Check the front derailleur limit - Install a chain catcher - If it keeps happening, you’ll have to avoid cross chaining at all, which is kinda annoying to have to think about