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Discussion Starter · #1 ·
Hi all.. On a new kona process111 dl.. 4 or so rides about 6 miles each-- so maybe 25 miles....

Im new to 1x setup and the bike is running xx1... The problem im having is--- if I back pedal, the chain is kicked off of the 42 ring down to the next lower ring... when i start pedaling ill be in the wrong gear then it will auto jump back up to the 42 tooth ring (not something i want doing under high load)... This is a brand new bike-- with sram's top groupset on it-- does this sound right to you guys or is there a problem? I was thinking maybe it had to break in a bit(loosen up) and then it would stop doing that -- but so far-- it keeps doing it.. Any way to fix this?
 

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i'm no expert, just talking out loud here. when spinning a chain backward you are for the most part taking away the RD ability to align the chain with the cog. since the front sprocket is theoretically aligned with center of the cassette I would assume pedaling backwards in that gear is no problem. but the more you move away from center the more the chain wants to return to that center position without the aid of the RD. from what I have read here this problem seems worse when dealing with larger gears, so I guess you could bias the front sprocket toward the bigger cog to aid in keeping the chain on when back pedaling. my guess is, that your bike is fine and you should just limit your back pedaling to only when you have to.
 

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Have a look at the chain line when on the 42t. You can't fix it. Try to stay off the 42 if possible. Maybe try a smaller chainring. Also +1 don't pedal backwards....
 

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I would check to make sure the hanger is totally trued to the rear wheel and then the wheel and cassette straight lined to the front chain wheel.
 

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I'm not sure why, but this issue seems to be a bigger deal with clutch derailleurs. I notice it a bit with my XT clutch turned on, and not so much with it off.
 

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We've seen this a good bit, some bikes are worse than others even with the same setup. Mainly it's an issue in the repair stand but not on the trail. I've seen it more with chains that have a couple extra links in them than chains that are exactly at spec. messing with the chainline sometimes help, sometimes made it worse. I have not found the perfect fix yet that works every time. I'd be glad to hear if someone has.
 

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Discussion Starter · #11 ·
why do you feel the need to back pedal...
there are 2 main times i need the bike or chain to be able to roll backwards without jumping gears..

1. when im going through a quick transition or coming up to a obstacle---i sometimes dont have time to bring the pedals all the way around to be in the best attack position-- so ill back pedal a bit.. Having the chain jump down to the next gear isnt the best when im already trying to get up and over something that would need me to be in the 42 tooth-- plus its a lot of strain on the drive train shifting back up a gear when your in a very high load situation...

2.. when going up a steep hill-- and i run into something that I cant clear and it stops me-- as i jump off the bike it will roll backwards a bit so i can .. If it then jumps out of the top gear(which assuming id need cause it was there to begin with)i then have to stop everything-- and turn the cranks manually so the gear jumped back up into the 42 tooth so i can start back up again..

Having the bike do this isnt the end of the world.. But if i can fix it -- im going to do my best to do so.. Having a bike come down a gear when you dont want it to is never the best situation..
 

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same situation here with my XX1 drivetrain popping off the 42T when backpedaling. Any fixes?

BTW, when climbing steep tech and an obstacle is in the way, back pedaling 1/2 crank may be necessary to optimize pedal position to help clear the obstacle. Maybe the experts are never in a situation to backpedal, but us mere mortals sometimes are.
 

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Chainline!!!

Perfect chainline on a 135 / 142 hub is 45mm.
xx1 chainset has a chainline of 49mm, so your chain is about 4mm wider than ideal when in the 42t.

Not much you can do about it really. It might get better as the chain wears a bit and gets a bit more flexibility.

If you're running a crank with a spider and 4 bolt chainring, you could add chainring spacers to offset the chainring in a bit.

Sram really could do with addressing this problem.
 

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^^ I did address this issue on a 1x10 by using spacers to correct the chainline. 2-3mm spacers were enough in my case.
 

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Don't back pedal on extreme chain line. problem solved.
Well...here's the thing...at times you do need to ratchet your pedaling. I did find at rare times I did need to slightly backpedal in the 42T. Like when I was going up some technical rocky terrain. It was like riding up steps of varying sizes with sand on top. I was in my in my 42 and if I kept pedaling in circles...my pedals would hit the rock and off the bike I go. So the only way to keep momentum was to ratchet my pedaling.
 

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I understand that and do the same as well on some technical climbs. The thing is though with the OP's problem usually it's not the 90 or 180 degree backpedal you describe which causes the problem. It's when you spin back a few full times (either to rest/stretch your legs etc) that causes an issue. The drivetrain is just not designed for that.

On my 1x10 11-40 conversion if I backpedal like that in 1st gear it will start to want to drop the chain.

Apologies if my first reply sounded derogatory.
 

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I'd also suggest to adjust your chainline. Remove a spacer on the drive side, see if it's better.
 
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