Chain slipping under load

bucknejo

Active Member
#1
My new chain on an older drive train (2015, low miles) seems to be slipping under load, i.e. standing on the pedals going uphill, but only in the low gears (40t, 36t). I removed a link as I thought my chain was too long, and that stopped most of it, but there's still some slippage. How short is too short for chain length? I'm thinking about removing another link if there's room to give.

My chain sizing routine I'm going with is running the chain through the biggest cog on the cassette (1x setup), fully extending the derailleur, then backing it off a little bit. This is with the rear shock fully depressed to ensure I have the longest effective chain stay length. Am I doing it wrong?

I dread anything other than a chain issue as I'd hate to have to replace a cassette, derailleur or hub.

If I end up pulling off another link, can I re-use the master link? It's an 11 speed ML and I've seen conflicting online chatter about single-use vs. re-use.
 
#2
This reminds me I have the same issue with the Evo - chain won't stay in the 11 and now even 12 tooth cog when in the 50 tooth crank ring, but only under load. Just going thru the gears on a stand it's fine. Really getting annoying. Maybe the cassette is worn?
 

Magic

Formerly 1sh0t1b33r
Team MTBNJ Halter's
#5
Check b-screw. Sounds like not enough chain wrap, or as others mentioned, mismatched chain-to-cassette.
 

bucknejo

Active Member
#6
Check b-screw. Sounds like not enough chain wrap, or as others mentioned, mismatched chain-to-cassette.
Ah! this one I need to try. When I put the new chain on I adjusted the b-screw, but didn't adjust it again after I pulled out the link.

As for the cassette - it's an XX1 with probably 500 miles on it, if that. Would a cassette wear out this fast? I'd like to say I keep the drive train pretty clean and maintained regularly.
 

huffster

Well-Known Member
#8
My chain sizing method has always been to string the chain around big front chain-ring and big rear cassette + 2 links. I read that somewhere a long time ago and I've used it ever since. Never had an issue. If I know I haven't changed the chain size due to some trail-side repair, then I just match the new chain to the old one coming off - assuming I was the one who put the last one on.

It is pretty difficult to figure out why a chain is skipping over the internet. Usually if you put it on a stand and roll really, really, really slow, you will see some little skip or catch point. I've had this same symptom be caused by several things: worn cassette, worn chain-ring, bent derailleur cage, miss-adjusted b-screw, worn derailleur pulley and bent derailleur hanger. So, in general worn or miss-aligned parts.

There may be some clues during the ride. For example, if it only happens in certain rear gears, that should eliminate the chain-rings.

Sorry, my advice is vague and lists many possibilities, but hopefully you figure it out.
 

fidodie

Well-Known Member
Staff member
#9
i had a washer (it was hard plastic) behind the cassette deform under load!! that was a tough one.
perhaps alp du zwift in the trainer will cause it to reveal :D
 

SmooveP

Well-Known Member
#10
"new chain on an older drivetrain." You answered your own question right there. New cassette and chainring(s) are probably the fix. A bent/misaligned derailleur hanger could also cause it, but if the only change you made was the new chain, and it didn't skip before, that's not likely.
 
#14
I confirmed on yesterday's ride that the new cassette was the fix. Stuck with same as before, 11 - 28, don't need the 30 tooth cog like @stb222 ! Nice to have 11 gears again instead of 9. Now wondering if the horsethief cassette is ready to go next, doesn't look great.
 

stb222

Love Drunk
Jerk Squad
#15
I confirmed on yesterday's ride that the new cassette was the fix. Stuck with same as before, 11 - 28, don't need the 30 tooth cog like @stb222 ! Nice to have 11 gears again instead of 9. Now wondering if the horsethief cassette is ready to go next, doesn't look great.
Might want to check you times before you make that claim.
 

fidodie

Well-Known Member
Staff member
#16
I confirmed on yesterday's ride that the new cassette was the fix. Stuck with same as before, 11 - 28, don't need the 30 tooth cog like @stb222 ! Nice to have 11 gears again instead of 9. Now wondering if the horsethief cassette is ready to go next, doesn't look great.
Might want to check you times before you make that claim.
the 30t is to stay in the big ring longer.....
 
#19
Sure, but if you are dropping in the 60s and 70s while climbing, you may be bogging down. The 30 allows me to spin in the 90s while climbing, which is my sweet spot.
Yeah I guess I should try it, I seem to set all my PRs climbing staying in the big ring but I tend to stand and grind