when the rear wheel spins the cluster wobbles
 

Haven't done alot of investigating yet but i'm working on fixing up an old Trek 1200 and when the rear wheel spins as if the bike were coasting the cluster wobbles. Any tips?

I don't know if you have a freewheel or freehub, freehub is when ou can slide the cogs on the freehub body. Most freewheel type cogs do this because you need some play in the freewheel or else it won't work. Even new ones do this. Now as parts wear out there will be more movement. If you think it's too much it wouldn't hurt to replace your chain and cogs. Freehubs do this alot less than freewheels. If you have a freehub and lots of movement than it's time for a new freehub.

Could be a loose cassette.

Could be a bent axle.

Both are cheap fixes.

Bob

You didn't state whether you just replaced the cassette and whether it's Shimano or Campy.

Just from what you said and the possibilities already stated, you can add a vote for missing spacers if it's a freehub.

It is a free wheel I believe. It is Shimano 105, the chainstay guard says "New Shimano 105" (I get a kick out of that) It is a 7 speed. The play is probably about 3 to 4 mm.

No parts have been replaced... yet.

I do not think I even have the proper tools for working on a free wheel...

Thanks

3-4mm is a bit excessive even for a freewheel in my (disclaimer: limited) experience. Though, as others have stated, all do have some wobble in them. I actually started pretty much the same thread a while back when I first discovered this behavior. New Shimano freewheels are pretty cheap, bikepartsusa.com has about the best price I've seen, or ebay is always a good option as well. You'll need a freewheel remover and a good large wrench to get the old one off. Or a freewheel remover and a vise is an even better option (put remover in vise, put wheel over remover, rotate wheel).

With as much play as you are describing, it could be a bent/broken axle. Either way, the freewheel will need to come off.

It's called 'dancing' and it's quite common, even up to 3mm. It sort of depends on what the relationship is between the hub and the freewheel unit. It could be what the guys are saying - bent axle etc. - but to be honest if it works fine then I would leave it be.

Hardly.

Freewheels wobble is from the gap that is usually present in loose ball bearing systems. Most freewheels have lots of tiny balls in two runs. The spacing in the balls changes constantly as the unit turns, creating the wobble effect.

It's normal; watch the road instead.

Quite common. In fact, if it doesn't wobble a bit, it won't freewheel.

OMG!!!!!!! Get a new bike!!!!!!!! It's possesed!!!!!!!!

Wow, you learn something every day! I was under the impression that it was because of the fit of the freewheel unit. Cheers for that, I apologise for misleading any folk.:o