Looking for some advice for my roadie. I replaced my original rims with some factory Mavic's a couple of months ago. I swapped the cassette over as this was fine and all seemed OK, needed to adjust the indexing as this was a bit out but all fine after that. I then noticed this week that there is lateral play in the cassette (a few mm of movement along the hub). I have checked the lock ring and this is still tight and the gears are still indexing OK when riding but I'm guessing that there should not be this movement?

I'm 100% sure that I got all the spacers in and in the right order when I swapped the cassette over so what do you think I should be checking for?

I've had this with an XTR cassette and a Hope Pro2 hub. I solved it by adding a very thin spacer between the hub body and the cassette. I think it was something like a sub 1mm spacer.

Oddly the problem did not transfer from one wheel to another, even though the wheels are using the same model hub.

Did you install a spacer first, before putting the cassette on? 10 speed cassettes need this. My shimano hubs need a v thin spacer, whereas my Ksyriums have a thicker spacer.

It would also explain your need to re-index.

This thread from a few weeks ago might offer some clues;

http://www.singletrackworld.com/forum/topic/cassette-gets-loose-no-matter-how-much-i-tighten-the-lock-ring-road-bike

Nice one. I need to check for spacers me thinks…