I have recently purchased a new best bike with a set of mavic cosmic's which are great except when it is a bit windy so in the recent weeks I changed the wheelset to my mavic ksyrium sl's but doing so meant I had to adjust the rear derailleur as the gears on the rear cassette would not seat properly and slip. Lots of chain chatter, obvious they are not seated properly.

I have never experienced this when changing rear wheels before and either the lbs used an incorrect spacer, the cosmics have a slightly different freewheel start point along the axle or this is completely normal.

Has anybody experienced this before?

Many thanks


jmaccelari [252 posts] 4 years ago

It's definitely not normal - I swap my wheels between several sets.

The two major possiblilities I can think of, given the available information, are:
- is the cassette properly built? For, example, is the thin, metallic spacer installed on the inside of the cassette (if required);
- are all the cogs on the cassette correctly seated and is the lock ring on the outside correctly torqued?

Other options could bs a worn cassette on the new wheels, a different gearing range, the new wheel not being correctly seated and so on...

nicdoye [33 posts] 4 years ago

I have two sets of wheels: handmade, Campag 9 speed hubs. They suffer from the same problem. There's enough of a difference to mean the rear mech would need adjusting. Pain in the bum.

mattswift1972 [1 post] 4 years ago

Thanks chaps for the quick responses. I'm pleased it doesn't sound right.

Can clearly see spacer has been fitted, was a new cassette on new wheels although can't recall a new cassette on old wheels needing gears adjusting. Wheel seated correctly, same gearing.

I'll check the cassette is seated correctly, must admit I haven't checked the torque but assumed the LBS would have been able to fit a cassette correctly. Then also try sl's cassette on the cosmic's and see if that results in any adjustment needed and vice versa that will rule out any difference in the cassette.

Failing that I'll just grin and bear it, to be honest it doesn't take long to readjust with di2 or manual adjuster it's just a pain that it has to be done.

racingcondor [238 posts] 4 years ago

Unfortunately it's normal. The tolerances hubs have to be made to are pretty small so occasionally you'll have one wheelset that's slightly misaligned.

If you're lucky you might be able to fix it with a spacer but if not you should find it's an eighth to a quarter turn on both limit screws.