I had this exact problem about 4 months ago, so I replaced the chain, cassette and chainring which fixed it. Chain was waxed and reapplied regularly but weather has been terrible so I’ve ridden in all sorts of conditions with every manner of muck getting into the bike. I estimate I’ve done 4k on this new set and I can’t see a large amount of wear on my chain ring?
Any ideas? I’ve been told it could be my rear mech which has played up on last few weeks and given a home repair…
Why is my chain skipping again?
byu/attendingcord inbikewrench
by attendingcord
12 Comments
In slomo I see it jumping off the chain ring. I’m curious if it is in the same part of the chain each time? That might mean a stiff link? Go through the chain and manual twist each link to check. If you find one just loosen it up by bending it in all its axis a few times by hand.
If not a stiff link, I would be curious if it is the chain ring or a toof that is bent? Take the chain off and from above or behind look to see by slowly pedaling through a couple rotations. If a bent tooth you can grab some pliers with maybe a cloth in-between and slowly bend the tooth back in place.
Have you used a tool to measure the chain wear?
Does the same behavior happen when you are in the road. Almost looks like the free hub is releasing on the trainer because a pawl is slipping. It appears that you are putting very little load and a chain/cassette/chain rings with only 4k and shouldn’t be getting a pop like that like if you had put a new chain on a worn cassette.
Can you upload the video at normal speed and a few more pedal revolutions ? Makes it easier to see the issue.
Simple things could be you’ve got a stiff link/ quick link isn’t installed correctly or your gears aren’t indexed properly.
Other possibilities are that your rear mech/ hanger is bent or the B screw isn’t properly adjusted.
Also check you’ve definitely got the correct quick link installed – is it the same speed as your cassette?
Either a stiff link, or wear again. 4k is decently much for a chain that had the muck you describe in what looks like 11x Ultegra at a quick glance. (correct me if I am wrong)
Did you check wear with a tool? With all the dirt you described it may just be worn. If you don’t yet own one, it will quickly pay for itself when you not run down a cassette and chainring because you caught it in time.
For context; I got about 3.5k out of my 11x chain on my gravel bike that sees a lot of sand and moisture while running on dry lube. And I do a proper clean at least every three rides, each ride if it is particular wet and/or far.
Do you have a different/newer cassette on your Zwift than on your bike?
It could be that the chain is stretched from road use, but it’s okay on the bike cassette which has worn in line with the chain, but now you’ve switched over to the Zwift the chain and cassette are at different wear stages.
Check chain wear and stiff links. Also, chain looks a tiny bit too long.
everything was working fine and then this started happening? Also youve done 4000 miles on this chain? Thats definitely worn out. Possibly already started to wear out the chainring too. Shimano recommends replacing a chain at around 2k miles which is conservative but 4k its definitely at the end of its life. Do you have an actual chain checker? Use that and if its past .75% wear id definitely say its a chainring and chain issue.
Might be time for a new chainring. And if that’s the case you probably want to get a new cassette too
I think the crocs might be the chief contributing factor
Top suspects:
Worn Chain
Worn Cassette
Slightly out of index.
Failing freehub pawls.
Bent/damaged teeth/rings you’d probably notice.
Are you using the cassette that came with your Zwift Hub? Cos it might be better to replace it with the same cassette you have installed on your wheel. I find that I have to tweak my derailleur whenever I stick my bike on my Zwift Hub.