Hello All,

I did a search but could not find the answer. I have a 2008 Trek Madone 6.9 with full Dura Ace 7800 group set. Double crankset and 10 speed (11-23) cassette. On the three middle cogs, every other tooth, it grabs the chain as it exits the cog. I can still ride the bike and the chain still runs fairly smooth, there's just an annoying clicking noise. I had an Ultegra (12-27) cassette before with no problems until I switched it out last night with the Dura Ace cassette. I dialed in the rear derailleur (limits, tension, barrel adjustments, etc.) but I have yet touch the B-tension screw. I will try that tonight. Anything else you guys think that can be the cause of that "grabbing" click noise.

Thanks

Clean and lube your chain.

Do both cassettes have the 10-speed spacer at the back of the cassette?
Does the 11-23 cassette have the special 11 cog lockring?
Were both lockrings set with the same torque?
Usually it's not necessary to adjust the cable tension when exchanging Shimano cassettes on the same hub.

no spacer at the back for either
just the standard cog lock ring for both
same torque used on the both
cleaned and lubed chain

All Shimano 10-speed cassettes are sold with a thin spacer that fits on the backside of the largest cog.
Any cassette beginning with an 11 cog needs a special lockring. A standard lockring will cause the chain to run on the lockring and not fully engage the 11 cog teeth properly. This usually causes chain skipping and excessive wear on the teeth.

So you're saying that the lockring that came standard with the Dura Ace 7800 11-23 cassette doesn't work? That would suck.

No, it (as does every cassette I'm aware of) comes w/ the right lock ring. Just don't mix it up w/ a different one.

No, cassettes starting with an 11 cog require a special smaller diameter lockring. In the past with some brands this smaller lockring has been sold separately. The lockring that came with you cassette should work with that cassette.

All other cassettes within a brand use the same lockring.

But what does the 11T lockring have to do with the chain sucking on the THREE MIDDLE GEARS as described in the first post?

Sanmano, is the Dura Ace cassete new or older? Typically you get that sort of chain suck either when the sprockets causing the trouble are older and worn to a hooked shape or if the chain is older and stretched slightly. But since you're saying that it's only an issue in three of the middle gears I'm thinking that you put in an older and fairly worn cassete.

Either the chain or the cassette is worn. Your chain probably wore in to your Ultegra cassette would be my guess.