Mountain Biking - Cassette wobbles

Hi,

I bought a Kona Cinder Cone a couple of months back and have been playing around with it as I like to get the bike setup perfectly. I've noticed though, that if I spin up the rear wheel, then let the bike freewheel, the cassette wobbles or moves slightly, almost like it's loose.

Is something loose? or damaged? It also every so often makes a slipping noise (during each revolution), although this is temperamental. I took the rear off and inspected it, but all seemed fine. I would dismantle the rear hub, but don't yet have the tools at my new place. Any ideas what it could be, and should I stop riding until I find out to stop any further damage?

I'd say take it to your LBS and have them check it over. I managed to whack my cassette into a boulder and it didn't bend, it simply became misaligned. :)

It's not spinning though when it wobbles. I spin up the wheel, and let it freewheel (on a stand) and the cassette wobles slightly (wheel is spinning and cassette isn't) and also moves very slightly in a backwards direction to which the wheel is spinning.

This is normal, assuming that your inspection was done correctly and you found no problems as you stated. My Trek cassette wobbles about 1/4th inch, whereas my Attitude (with a NukeProof hub) wobbles less than 1/16th inch. Generally speaking, the higher quality the hub, the less it will wobble.

I wouldn't worry about it, but if you are going to worry then just take it to your LBS to ease your mind.

I don't know how nice the cinder cone is, but it may have a freewheel instead of a cassette and I have seen many bent axles that cause that freewheel to wobble like that. If you want to check that just drop the back wheel and spin the axle and see if it stays straight or not.