TriDevil

I've started recently to notice my cassette wobbles from a little bit. It doesn't do it all the time. I will be spinning along, then notice a little clanking sound, look down, and the cassette is going left and right, not as a whole unit but the cogs will point towards the left side of the bike, then to the right. I'll change gears a few times and it goes away, spinning straight as it should. I had the wheel into my LBS and asked them to look at the rear wheel. They didn't see anything wrong or note anything. What could it be? I just put a new chain on and am waiting for the LBS to get a cassette in the range I want. It did this both with my old chain and now with my new chain. I am running an Ultegra double.

roadfix

As you're freewheeling you notice this, correct? I've noticed several of my hubs do this to a small degree but never caused any problems. I wouldn't worry about it. Perhaps a very slight machining error could be the cause???

TriDevil

This occurs while I am pedaling. I am kind of worried about it because I don't want my cassette to get loose and completly screw something up. Like I said, if I shift gears around a couple times then go back into the gear I was in and spin like normal it is fine. Then for no reason it seems, it will wobble.

GreenFix

Ditto the Fixer's response. I noticed it on a new Deore hub, and I asked a career wrench about it. He said that most of the hubs he works on have some sort of wobble to them and assigned it to the same problem Fixer's suggested.

If you are really worried you can have the lock nut retorqued. Usually it says on the locknut what the proper torquing is (40nM for mine I think).

roadfix

Does this occur while you're freewheeling as well?
Maybe your cassette is not mounted on square onto the hub body. Remove and remount, and torque down that lockring.