Does it cause a problem while you are riding?

Yes, its very noticeable while riding. I rotated it slowly in the video to capture it but at normal RPMs it makes a big clunk that almost feels like a downshift.

Given what you've already checked, I think your next move should be to remove the cassette and inspect the freehub. Does it spin free? Take the freehub off the hub and inspect the internals, it could be a stuck or broken pawl.

You've tried different chains and cassettes, so my bet is freehub.

Good idea! I haven't thought of that. I'll give that a shot. I can also throw my race wheel on and see if that makes a difference.

The question of riding is less revolution rate than chain tension.

It's not uncommon for the chain to catch a little on teeth when a drivetrain is rotated at low tension. It makes sense that a "worn" chain would see less of it, since there's more room between the rollers for the tooth to roll out of.

It would be weird if it was getting severely caught on the teeth even under pedaling tension, though.

So... it seems that you have eliminated the chain and the cassette from the equation, which would seem to leave you with it being a bike thing. Since it is happening on the top side of the cassette, the derailleur ought to be out of the equation too.

I played it frame-by-frame, and it looks like it is happening at the exact same spot on the cassette-- the 11-cog tooth that is just past the M in the "SRAM" on the lock ring. It may do it once on the tooth over the letter "A," but it was not as severe. It looks like chain plate is pressing against that tooth on the 11 cog at the moments that it does the jump. And, it is tough to tell, but it seems like maybe that tooth is more squared off than others.

At a macro view, it looks like the chain is too wide. Alternatively, any chance you used the same 11 tooth cog with both cassettes?

This is the tooth that seems to be associated with the jump.

If it’s a new cassette maybe the spacer or the cog itself is out of tolerance.

Maybe use an old spacer, if you have one, and see if the problem persists.

The spacers are usually built-in to the two smallest cogs on most cassettes I have seen.

He mentioned above he tried swapping out different cassette and chain.

Gotta be the freehub, I'm 93.7% confident. ;)

Yes, they are on this cassette. I definitely didn't mix up any of the cogs or spacers between the 1170 and older 1130 cassette. I'll have another look this evening when I get home.

Thanks for the tips everyone!

Are you using the new cassette lock ring or the original?

New lock ring, the one that came with the cassette.

I don't understand. Why freehub will cause this??? To me, chain got stuck between two cogs. Basically, there's not enough space. Are you using a correct Sram compatible chain? Chain looks bit wide to me. I have Shimano drivetrain, so I'm not familiar with Sram components though.

I'll try to explain....
Lets say you are pedalling your bike, rolling along. Then you stop pedalling but are still coasting. Your chain and cassette won't be in motion at all because you aren't pedalling and your freehub internals are spinning. If something catches on those internals, it will cause the cassette to kind of lurch forward, and when that happens the chain has no where to go because you aren't pedalling the crank around, thus it folds on itself like in the video.

I know the OP didn't say it was when he stopped pedalling, but something like that can happen in a split second when letting up a bit on the pedals, etc.

Check da freehub :)


Oh, can also rule out cassette/chain issue by taking the cassette off and putting it onto a different wheel, put that wheel on and see if problem persists...

I'm with you. That cog looks off. Too wide or the chain is too wide.

Are you sure that is an 11 speed chain?

It has lots of miles and you are have 0.0 wear? I go through chains every 4-6 months. I can't imagine lots of miles with no wear

I got it!!

I would bend the teeth of 12t cog to outside where it catches a little bit and see.

from what I see on the video the wheel is supposed to be freewheeling? if that is the case then it is almost certainly the hub. If you watch carefully the wheel turns without the cassette turning then all of a sudden it catches and jumps. I suspect there is something wrong with the pawl spring(s). So to me the key question is are you turning just the wheel or are you pedalling? If the former it is not freewheeling properly and this is the problem. When the wheel turn in the forward direction the cassette should not move or almost not at all. Spin the wheel backwards does the same thing happen with the pawls engaged?

Definitely worth pulling the freehub body and checking the pawls, springs, hub bearings, and axle. Inspect the entire length of your quick release as well.

Good luck!

I'm with the "chain pins stuck" camp.
Look at used cassettes. They all have pins stamped near every teeth.
Also, you're not putting enough pressure on the chain to really test it.
And your stuff is wayyy too clean. You need some lubricant on there ;-).
Wax is a like a glue at this amount of pressure and speed.

LOuis :-)

FWIW, I was having a similar problem. Tried lots of fixes. Ultimately solved it by putting on brand new chain and brand new cassette. Don't know exactly what was wrong, but I suspect there was uneven wear between the chain and the cassette. Might have been a chain line issue.

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No coasting in running and no crying in baseball

Were you able to resolve this? What was the issue??

OK, here's the update:

I pulled the freehub and everything was fine. I put the cassette on my race wheel and still had the problem. I looked closer and the chain is getting wedged between the 11T and 13T cogs at one point, as exxxviii pointed out above. The chain is an 11 speed and I also measured the pin width at 5.4mm (11 speed). I had the cassette lock ring on fairly strong and i backed it off to "snug" and it helps. That is not a solution though. I threw my old cassette back on and the issue seems to be gone. I'm thinking that a tooth on the 13 or 11 cog is bent toward the 12T causing the pinch point. Since this might be the case, and I just bought it, I'm going to take the bike in to the LBS and let them sort it out. I'll report back once it's solved!

To those mentioning about chain tension, load on the pedals, etc. This happens at load as well. happens under light loads to heavy sprint loads. I just rotated it slowly for video purposes.

Another that I've run into on occasion is a chain that doesn't match the rest of the drivetrain's tolerances. A few years ago we got a bad batch of Taya chains, which were slightly too tight and would do a similar catch on Shimano derailleur pulleys. The chain was tight enough that I could actually hang a derailleur by the pulley:

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"I'm thinking of a number between 1 and 10, and I don't know why!"

Thats great if a new cassette resolves it for you.
I thought for sure that it wasn't the cassette only because you mentioned in your first post that you tried both a second cassette and chain, and the issue persists. So do both your cassettes have bent teeth?

One suggestion - if you do get another cassette, get an Ultegra cassette instead. I've always found they run smoother than SRAM cassettes. Literally everyone I know that has SRAM components use shimano cassettes.

Cheers