Worn lockring threads or hub?

[milhouse]

Hi - just wondering if anyone can help with a mechanical problem.

I've got a sram 10 speed cassette on a Mavic Cosmic Carbon wheel and using the required 'thin' spacer. When I try to tighten up with the cassette on, I can tighten so far & then it 'slips' and I need to rescrew it on again. I've done a couple of rides where the lockring has come loose & the cassette started rattling.

My LBS thought the threads were worn on the lockring, so put on a new one, but the problem is still there after 3 rides. I've tried different lockrings now, can tighten properly with no cassette on, but doesn't work when there is - any ideas? Is my hub buggered?

Thanks!

[mandasol]

Did you check the threads in the freehub body? Sounds like a few of the first threads might have been stripped and even with new lockrings you're not getting a good contact. If that is the case you just need a new freehub body, so you're whole hub is not trashed. I'm not sure about Mavic, but I've gotten replacement freehub bodies for about $60.

[dogdriver]

Is the cassette by chance a RED? I had the exact same problem with a one-season old CK road hub and a new RED cassette. Would screw it on, think it was tight, and either the ring would pop off immediately or shortly after starting a ride. Tried the CK lock ring with no luck. Long story endless, I threw on a Force cassette and it worked perfectly. Measured the "thickness" of the RED cassette, and it was about 3mm thicker than any other cassette we measured it against. SRAM replaced the cassette, no questions. Apparently, some of the red base-plate "powerdome" thingies aren't flat as they need to be. During this process, we also discovered that some mountain cassette lock rings have an extra thread or two over the road lock ring-- just be sure that the mtb ring, if you use one, is small enough as not to interfere with the small cog/chain on the cassette.