I believe cable tension on derailleur, indexing, and limit screws can effect it. Though this is all from me working on my bike
Post below reminded me derailleur hanger too. Anything that would affect chain line.
You can see the derailleur stutter with tension and the chain line in reverse so it wants to shift in reverse down with the tension. That’s me thinking aloud so know idea if it’s correct
Bike mechanic here. You all can stop posting comments, this one here is correct. There is nothing you can do about it, your shifting is perfectly fine, even on dura ace road shifting it does that. It is absolutely normal.
Maybe pin this comment
Edit: let me put it that way. Your chain drops above the cassette. Your derailleur is below the cassette. Nothing you could do below the cassette will ever change how your chain behaves above the cassette. Even shifting itself happens BELOW the cassette.
Honest question. Not trying to argue, just trying to learn. Also, to be clear, I also agree that a chain changing gear when back pedaling is not a problem.
I am just curious about if there is nothing to about it. Couldn’t one move the chainring inwards or outwards? I know on the cranks I have I can attach my chainring on the outside or inside of the arms it bolts on to. I have some spacers that came with the cranks that I assumed was to move the chainring a few mm in or out. Wouldn’t that change the point from where the cassette pulls the chain when backpedaling and also change how the chain skips? It would not necessarily mean that it’s possible to make the chain not skip on every set up, but should it not be change how and possible what gears skip when backpedaling?
So hypothetically yes. What you describing is changing the chain line. The problem with that is that it doesn't help you when shifting. As simple as possible: You want your chainring as centered to the cassette as possible. Not to far outside of the bike, not to far inward because it leads to misshifts, rubbing on the chain, faster wearing and the chain dropping from the chainring when the chainline is poorly aligned.
Normally you allign the chainline by e.g. choosing the correct bottom bracket for you frame when you have a square tapered bottom bracket. The actual shaft has different length depending on your bike. The most common being 112mm and 123mm. If you have a hollowtech bottom bracket you can adjust your chainline by using the plastic spacer rings that are in the package, if your bottom tube has a width of 68mm. If it is 72mm your bike is already build for hollowtech cranksets to have a good chainline. (Most of the time)
So you could adjust your chainline to be more inward so you don't have these slips when backpedaling on a low gear but that would lead to your chain dropping in the front when you shift into your highest gear. That's not really a problem with a proper narrow-wide chainring on a 1x drivetrain but you still have all the other problems.
I hope this gave you a basic idea. Tldr: don't adjust your chainline and your shifting just because it's noisy when backpedaling. If it's perfect when pedaling forward, then there's nothing you should do in the back. No matter what it is doing when backpedaling
Edit: If your chainline isn't adjusted correctly you need to adjust it for the best shifting possible but if your shifting is perfect, than you shouldn't touch it just for the backpedal.
Never stop a running system.
Unless you want to adjust your chain line somehow, there isn’t really anything to be done. There is nothing wrong that needs fixed.
I wonder if a newer chain does this less because there is less flexibility and tighter tolerances. As the chain wears, it may allow for this slip to happen more. That could be why people perceive it as getting “worse” over time.
The only way is to put spacers on the crank chainring to move it inboard. It depends on how severe the chainline is. A few millimeters is doable, more than 3 or 4 mm is probably not.
Incorrect. Cable tension is not relevant to chainline, which is what causes backpedaling issues.
This sub is so fucking bad for poor advise. Please stop helping people until you actually can.
The issue is caused by the angle the chain comes in at from rear cog to chainring. There is no upper guide to hold the chain onto the cog when pedalling backwards, such as there is when pedalling forward and the derailleur is guiding the chain.
Simply put, it's the chainline, and drivetrain tension is irrelevant. The tension will only effect what the derailleur works with, aka pedalling forward.
This is normal, it happens because on wide, modern cassettes (e.g. 12x) the angle of the chain when it sits on the smaller gears (larger diameter cogs) is so steep that the cogs catch onto the chain and pull it down. They are designed to do this so that the chain jumps efficiently when the derailleur moves it. The chainring of course doesn't have any features to make the chain jump so it only does this in one direction, even though the angle is the same on the rear cog and the front chainring.
Are you using a Shimano chain? Because I have 4 XT setups and 2 GRX, mix of 2x11 and 1x12, and none of them do this. One had GX before and did this consistently.
Exactly this. Top commenter was wrong. The chainline is more extreme.. doesn’t have the derailleur to guide it when back pedaling so it drops down to a cog with a straighter chainline
Most commenters here simply do not know sram 12x behavior. Your GX, properly set up, should rarely drop on backpedal in gear 2 (second lowest). Gear 1 should tolerate a minimum of a full 360 degree CRANK rotation backwards (often 2-3) before dropping. This is with the standard boost 3mm offset front sprocket and correct cassette/hub location, b-adjustment, tension, alignment, etc. Yours needs some work.
Not a worn chain. Derailleurs only work when pedaling forward. you can only expect the chain to stay on when you pedal backward if your in a middle gear so that the chain line is relatively straight. Nothing wrong, keep going forward and enjoy!
This has nothing to do with b-tension adjustment or any adjustment besides chainline. When back pedaling there is nothing guiding the chain onto the cassette because it's going into the cassette from the top instead of the bottom (through the derail cage). Chainline to the front chainring is shit on the top/bottom of the cassette so the chain falls (or sometimes climbs if in the smaller cogs) when pedaling backwards. Don't pedal backwards like a kid on a bmx bike.
There are a lot of people on here that are saying this is normal amongst 1x. This has nothing to do with cable tension.
The correct answer would be your b tension. Set your b tension with your chain in your lowest gear.
I have a 2x10 and had this issue when I put on a Shimano chain. No such problems with a KMC chain. They are more forgiving with crooked chainlines.
That said, I have no substantial experience with 1x12, apart from that I hate them with a moderate passion.
Happened to me when my chain and cassette were used. Maybe I could have just changed the chain but I be got a 50% deal on the X01 cassette. I hope the X01 stuff will last longer. This is my first SRAM drivetrain and I m not impressed
The downside of a 1x drivetrain. But hey everyone is a sheep that thinks less is more when in fact it really isnt. Fuck chainlines and drivetrain efficiency.
Many people say this is normal on bikes, which is not entirely wrong. It just is. It's more likely to occur with 1x drivetrains.
But I've also found out that there's certain rear hub designs that have more resistance to ratcheting. That additional force to start the cassette rotating backwards makes it more likely for the chain to fall back into a smaller gear.
So upgrading to a hub with a lower drag when ratcheting will reduce the liklihood of this happening. It won't eliminate it, but it can make it so a quick swap of which feet are forward won't shift.
This is normal.
You chain line at the extremes of the cassette on a 1x drivetrain is such that back pedalling will cause it to drop gears.
If it’s just started happening you could check your hub for wear… maybe increased resistance to backpedal would not help.
Some bikes do this from new, others develop it as the chain and cassette wear, others will never have it. Depends on the sprocket size, chainline and chainstay length.
I know it happens on some bikes and doesn't on others.
But I once tried to resolve it by changing the cassette and it worked.
It used to drop on half a back pedal and after the new cassette, it won't drop no matter how many times I back pedal.
So, I guess it's fixable?
That was on a Canyon Spectral running XT
I now have a Forbidden Druid V2 with GX T-Type and its never happened. Not even once.
Mine does this, and on my favorite trail, there's a creek crossing right before a big uphill section, and no matter what I do, it always slips right there making me lose all momentum at the bottom of the hill. I've tried everything to fix the issue including multiple shops. Used bike too, so I'm kind of sol.
Of course, it's something about the little ravine right there at the transition from the creek to going uphill that gets me everytime in the same spot. It's very frustrating and I try to do something different or really focus on keeping the tension on the chain, and sure enough, everytime in the exact same spot.
I don't even think I'm back pedaling there, I think it's a little bump right when I'm in my high gears that causes it to slip or something. I wish I knew, trust me. It's only this one spot on all the 30+ trails near me.
First check your b-screw setup because if the there is too much gab between the jockey wheels and the largest cog, it will easily drop the chain when back pedaling. Always pull back the derailleur with every adjustment of the b-screw because if there is tension on the b-screw when adjusting, you could strip the screw. You want to keep the gap as close to the largest rear cog as possible, without hearing any sort of rub when shifting. Then proceed with shifter setup and shift cable tension on the lowest cog. You then move to check chain length and chain alignment, along with derailleur hanger alignment. Derailleur hanger alignment is almost always overlooked, and will cause chain drop issues. Any of those will cause it. Contrary to many rider’s beliefs, the chain should absolutely not be dropping just after a few back pedals because that represents an improper setup somewhere in the process mentioned above.
A lot of bikes will drop the chain back peddling on the top gears. If yours just started doing it and it didn't do it before, you make have several things at play. Chain stretch, bent derailleur, limit adjustments, or drive line adjustment, bad teeth on the cassette, or something else.
If you've looked it over and can't figure it out, support your local bike shop and let them give it a proper adjustment. Cost very little and your drive train will run like new. Or they will let you know what parts you may have damaged.
If you haven't already, check your chain and ensure it isn't stretched. A stretched chain will destroy your cassette and chain ring. The chain should only be around $80 rather than spending more on a cassette and chain ring.
Rusted pin in the chain! Happened to me usually used a pair of pliers and chain lube and wiggled the affected link up and down till it moved freely again
Hey OP if you’re on a FS bike it’s your b gap which would need to be set at sag. Does it still fall with you on the bike? Get a friend to adjust the b gap to spec if so. If it’s a HT, adjust b gap to spec and you should be okay.
Im no expert, but try cleaning your hub!
I think the hub doesnt want to move that easy as it moved before and thats why the chain drops (just an idea, i can be horribly wrong here)
Chain line on the bigger cassettes. Isn’t a huge deal while riding unless you’re bored free wheeling right before a climb.
It's not a big deal, it just started happening though and I'm curious why. Could it be a symptom of a worn chain?
It’s just the design of the huge cassette. There’s nothing to keep it in gear while going backwards.
I believe cable tension on derailleur, indexing, and limit screws can effect it. Though this is all from me working on my bike Post below reminded me derailleur hanger too. Anything that would affect chain line. You can see the derailleur stutter with tension and the chain line in reverse so it wants to shift in reverse down with the tension. That’s me thinking aloud so know idea if it’s correct
When its back pedalled, the derailleur has no impact, the chain is being pulled off the gear by the input angle from the chainring.
Bike mechanic here. You all can stop posting comments, this one here is correct. There is nothing you can do about it, your shifting is perfectly fine, even on dura ace road shifting it does that. It is absolutely normal. Maybe pin this comment Edit: let me put it that way. Your chain drops above the cassette. Your derailleur is below the cassette. Nothing you could do below the cassette will ever change how your chain behaves above the cassette. Even shifting itself happens BELOW the cassette.
Hold up. By that logic you’re telling me the rear derailleur can’t change the front gears? 🤯 /s
Honest question. Not trying to argue, just trying to learn. Also, to be clear, I also agree that a chain changing gear when back pedaling is not a problem. I am just curious about if there is nothing to about it. Couldn’t one move the chainring inwards or outwards? I know on the cranks I have I can attach my chainring on the outside or inside of the arms it bolts on to. I have some spacers that came with the cranks that I assumed was to move the chainring a few mm in or out. Wouldn’t that change the point from where the cassette pulls the chain when backpedaling and also change how the chain skips? It would not necessarily mean that it’s possible to make the chain not skip on every set up, but should it not be change how and possible what gears skip when backpedaling?
So hypothetically yes. What you describing is changing the chain line. The problem with that is that it doesn't help you when shifting. As simple as possible: You want your chainring as centered to the cassette as possible. Not to far outside of the bike, not to far inward because it leads to misshifts, rubbing on the chain, faster wearing and the chain dropping from the chainring when the chainline is poorly aligned. Normally you allign the chainline by e.g. choosing the correct bottom bracket for you frame when you have a square tapered bottom bracket. The actual shaft has different length depending on your bike. The most common being 112mm and 123mm. If you have a hollowtech bottom bracket you can adjust your chainline by using the plastic spacer rings that are in the package, if your bottom tube has a width of 68mm. If it is 72mm your bike is already build for hollowtech cranksets to have a good chainline. (Most of the time) So you could adjust your chainline to be more inward so you don't have these slips when backpedaling on a low gear but that would lead to your chain dropping in the front when you shift into your highest gear. That's not really a problem with a proper narrow-wide chainring on a 1x drivetrain but you still have all the other problems. I hope this gave you a basic idea. Tldr: don't adjust your chainline and your shifting just because it's noisy when backpedaling. If it's perfect when pedaling forward, then there's nothing you should do in the back. No matter what it is doing when backpedaling
Edit: If your chainline isn't adjusted correctly you need to adjust it for the best shifting possible but if your shifting is perfect, than you shouldn't touch it just for the backpedal. Never stop a running system.
No, that makes sense and show I thought it worked.
Wilt that "it's just how it is" but some bikes do it and some don't, which would lead one to believe that there's a way to fix it.
Unless you want to adjust your chain line somehow, there isn’t really anything to be done. There is nothing wrong that needs fixed. I wonder if a newer chain does this less because there is less flexibility and tighter tolerances. As the chain wears, it may allow for this slip to happen more. That could be why people perceive it as getting “worse” over time.
Yes, that's it. But again, that's still normal and doesn't mean that your drivetrain would be worn out...
The only way is to put spacers on the crank chainring to move it inboard. It depends on how severe the chainline is. A few millimeters is doable, more than 3 or 4 mm is probably not.
FingerBangMyAsshole, thank you for clearing that up.
You are welcome!
Ahh ok. Thanks
Limit screws cannot affect this
Thought the same as they both aren't on the limit.
Thank you!
Incorrect. Cable tension is not relevant to chainline, which is what causes backpedaling issues. This sub is so fucking bad for poor advise. Please stop helping people until you actually can. The issue is caused by the angle the chain comes in at from rear cog to chainring. There is no upper guide to hold the chain onto the cog when pedalling backwards, such as there is when pedalling forward and the derailleur is guiding the chain. Simply put, it's the chainline, and drivetrain tension is irrelevant. The tension will only effect what the derailleur works with, aka pedalling forward.
Do you think that this gets “worse” as a new chain wears and has looser tolerances? That could explain why people think it changes over time.
No relevance.
Ya that’s why I mentioned my experience and started with chain line. Always comes up and I’ve had it stop or start. SRAM or shimano info would be cool
The opposite. A new chain is going to have less flex. Don't backpedal in lower gears.
Derailleur hanger alignment as well.
Aye. Not torqued to spec or bent ever so slightly even
Homie literally just said what it is: chainline. Why bother asking if you wont be receptive to the answer?
Thanks for posting this as someone new to 1x I was having the same issue after a cleaning and oiling. Thought i messed something up.
Ah shit,here we go again
Yep. Get ready for a month of chain line posts, and people arguing over it.
The only answer is that must be carefully recycled, you must ship the bike to me asap.
It's a 1x.
This is normal, it happens because on wide, modern cassettes (e.g. 12x) the angle of the chain when it sits on the smaller gears (larger diameter cogs) is so steep that the cogs catch onto the chain and pull it down. They are designed to do this so that the chain jumps efficiently when the derailleur moves it. The chainring of course doesn't have any features to make the chain jump so it only does this in one direction, even though the angle is the same on the rear cog and the front chainring.
Uhh, no.
Only on SRAM and cheap AliExpress cassettes.
My XT does this and my GX does not
Are you using a Shimano chain? Because I have 4 XT setups and 2 GRX, mix of 2x11 and 1x12, and none of them do this. One had GX before and did this consistently.
It's still stock from the manufacturer. Less than 300 miles on it. I had it checked by my LBS and they said it just happens with 1x12s.
Crazy, definitely not on all setups. What frame is this on? Maybe it's a chainline issue.
Transition Spire
It’s not the cassettes. It’s the bike’s chain-line. If your bike has an extreme chain-line it doesn’t matter what cassette you have on there.
Exactly this. Top commenter was wrong. The chainline is more extreme.. doesn’t have the derailleur to guide it when back pedaling so it drops down to a cog with a straighter chainline
My brand new XT does this. I find it really annoying. Haven’t tried to fix it yet though, but definitely intend to.
False.
Normal
Maybe don't back pedal in those gears?
Most commenters here simply do not know sram 12x behavior. Your GX, properly set up, should rarely drop on backpedal in gear 2 (second lowest). Gear 1 should tolerate a minimum of a full 360 degree CRANK rotation backwards (often 2-3) before dropping. This is with the standard boost 3mm offset front sprocket and correct cassette/hub location, b-adjustment, tension, alignment, etc. Yours needs some work.
Balls.
Not a worn chain. Derailleurs only work when pedaling forward. you can only expect the chain to stay on when you pedal backward if your in a middle gear so that the chain line is relatively straight. Nothing wrong, keep going forward and enjoy!
This is normal on many 12spd drivetrains
There is no derailleur guiding where it goes. So it goes towards a natural chain line. Zero issues.
Had the same problem. Bike shop put a spacer in which helped.
This has nothing to do with b-tension adjustment or any adjustment besides chainline. When back pedaling there is nothing guiding the chain onto the cassette because it's going into the cassette from the top instead of the bottom (through the derail cage). Chainline to the front chainring is shit on the top/bottom of the cassette so the chain falls (or sometimes climbs if in the smaller cogs) when pedaling backwards. Don't pedal backwards like a kid on a bmx bike.
It’s normal for 1x system
There are a lot of people on here that are saying this is normal amongst 1x. This has nothing to do with cable tension. The correct answer would be your b tension. Set your b tension with your chain in your lowest gear.
I have a 2x10 and had this issue when I put on a Shimano chain. No such problems with a KMC chain. They are more forgiving with crooked chainlines. That said, I have no substantial experience with 1x12, apart from that I hate them with a moderate passion.
Error in design regarding the chain line. Is a pain in the ass to fix
Srams man, same thing happened to me it was so frustrating. Made me switch to shimano forever
Happened to me when my chain and cassette were used. Maybe I could have just changed the chain but I be got a 50% deal on the X01 cassette. I hope the X01 stuff will last longer. This is my first SRAM drivetrain and I m not impressed
Happens in big cassettes. This is normal
The downside of a 1x drivetrain. But hey everyone is a sheep that thinks less is more when in fact it really isnt. Fuck chainlines and drivetrain efficiency.
Many people say this is normal on bikes, which is not entirely wrong. It just is. It's more likely to occur with 1x drivetrains. But I've also found out that there's certain rear hub designs that have more resistance to ratcheting. That additional force to start the cassette rotating backwards makes it more likely for the chain to fall back into a smaller gear. So upgrading to a hub with a lower drag when ratcheting will reduce the liklihood of this happening. It won't eliminate it, but it can make it so a quick swap of which feet are forward won't shift.
Chain line can help with this, I swapped to a chainring with different offset to help
Quirk of the system, learn to not backpedal more than a half stroke.
This is normal. You chain line at the extremes of the cassette on a 1x drivetrain is such that back pedalling will cause it to drop gears. If it’s just started happening you could check your hub for wear… maybe increased resistance to backpedal would not help.
Some bikes do this from new, others develop it as the chain and cassette wear, others will never have it. Depends on the sprocket size, chainline and chainstay length.
I know it happens on some bikes and doesn't on others. But I once tried to resolve it by changing the cassette and it worked. It used to drop on half a back pedal and after the new cassette, it won't drop no matter how many times I back pedal. So, I guess it's fixable? That was on a Canyon Spectral running XT I now have a Forbidden Druid V2 with GX T-Type and its never happened. Not even once.
Votre chaîne n’est pas assez tendue. L’impulsion que vous donnez en rétro pédalant fais sauter cette dernière
Rebuild the hub
Mine does this, and on my favorite trail, there's a creek crossing right before a big uphill section, and no matter what I do, it always slips right there making me lose all momentum at the bottom of the hill. I've tried everything to fix the issue including multiple shops. Used bike too, so I'm kind of sol.
Have you tried not back pedalling there?
Of course, it's something about the little ravine right there at the transition from the creek to going uphill that gets me everytime in the same spot. It's very frustrating and I try to do something different or really focus on keeping the tension on the chain, and sure enough, everytime in the exact same spot. I don't even think I'm back pedaling there, I think it's a little bump right when I'm in my high gears that causes it to slip or something. I wish I knew, trust me. It's only this one spot on all the 30+ trails near me.
I think your derailleur hanger is probably bent
First check your b-screw setup because if the there is too much gab between the jockey wheels and the largest cog, it will easily drop the chain when back pedaling. Always pull back the derailleur with every adjustment of the b-screw because if there is tension on the b-screw when adjusting, you could strip the screw. You want to keep the gap as close to the largest rear cog as possible, without hearing any sort of rub when shifting. Then proceed with shifter setup and shift cable tension on the lowest cog. You then move to check chain length and chain alignment, along with derailleur hanger alignment. Derailleur hanger alignment is almost always overlooked, and will cause chain drop issues. Any of those will cause it. Contrary to many rider’s beliefs, the chain should absolutely not be dropping just after a few back pedals because that represents an improper setup somewhere in the process mentioned above.
You have no idea what you're talking about.
Tighten up the B-gap.
A lot of bikes will drop the chain back peddling on the top gears. If yours just started doing it and it didn't do it before, you make have several things at play. Chain stretch, bent derailleur, limit adjustments, or drive line adjustment, bad teeth on the cassette, or something else. If you've looked it over and can't figure it out, support your local bike shop and let them give it a proper adjustment. Cost very little and your drive train will run like new. Or they will let you know what parts you may have damaged. If you haven't already, check your chain and ensure it isn't stretched. A stretched chain will destroy your cassette and chain ring. The chain should only be around $80 rather than spending more on a cassette and chain ring.
Rusted pin in the chain! Happened to me usually used a pair of pliers and chain lube and wiggled the affected link up and down till it moved freely again
Hey OP if you’re on a FS bike it’s your b gap which would need to be set at sag. Does it still fall with you on the bike? Get a friend to adjust the b gap to spec if so. If it’s a HT, adjust b gap to spec and you should be okay.
Clean and lube chain . Been there done that
Im no expert, but try cleaning your hub! I think the hub doesnt want to move that easy as it moved before and thats why the chain drops (just an idea, i can be horribly wrong here)
Normal? Not at all. Probably not enough cable tension.
I would say too much B-screw