Hi all,
I recently equipped a Srly Krampus mtb with a SRAM GX Eagle groupset.
It has a 30t chainring and 10-52 12sp cassette.
The chainline I measure is 52mm as specified by SRAM.
The issue I have is that when I'm in the largest cog (52) and backpedal even 3/4 of a turn the cog teeth dont align with the chain and push it down several cogs.
Apart from this inconvenience everything else works as expected.
I have adjusted the b gap using the included gauge.
I understand that 1x groupsets, and boot ones like this one even more so, have chainline issues but this seems something a bit weird. I don't backpedal much but on steep climbs it is frequent that, for one reason or another, one needs to stop and quickly reposition pedals for a restart: this always leads to the chain falling and it is very annoying.
I could try reducing the chainline, (as the chain seems to be much more bent when in the big cog than in the small one) by using a smaller spacer between the BB and the ds crank arm but the tollerance between the chainring and the chainstay is quite narrow.
What do you suggest?
Thank you very much!
Chain falling down to smaller cogs when backpedaling – SRAM GX Eagle
byu/Scott_Korman inbikewrench
by Scott_Korman
3 Comments
I’m sorry I don’t have the exact/mechanical answer someone else could chime in but I thought back pedaling on a 1x system just doesn’t work and you will most likely drop a chain or in your case a few gears. Sometimes you can get away with it depending on cassette wear but I’m pretty positive this is a byproduct of going 1x
When riding the bike how much are you pedaling backwards? In real life this isn’t a problem. There’s not an adjustment for it either. Possibly shifting to a gear with a straighter chainline. Don’t worry about it and just ride your bike. It’s fine.
Yes, it’s normal for such a chainline setup.
Got a new 1×12 GRX – and it’s the same here.
Was wondering if this would be annoying. To me it’s not. Never had it happen actually riding!