paul8f

Hi,

having some problems with my rear wheel. It's two years old with a Shimano XT (M760) hub.

When I first got the wheel, there was a lot of resistance when it was spun (it would come to stop very fast). The cones were overtightened against the bearings. I stripped down the hub, cleaned everything, re-packed it with grease and re-built it.

It's now spinning freely but there is a little side to side rocking motion with horizontal pressure applied to the wheel. I've checked the axle for any rocking motion and it seems to be okay and the axle isn't bent. The freehub body is also securly mounted to the wheel. I'm confident that the cones are snug against the bearings.

I'm thinking that this play on the wheel could be due to the free hub body. Is this possible? If it is, does it have to be replaced or can it be repaired. (A replacement is about €45). Could damage have been caused by the cones being overtightened?

Thanks,
Paul

Rev.Chuck

I can't say what it is, but I don't think it is the freehub.

tonyt

Freehub might make the cassette wobble but not the wheel. I'd recheck your bearings.

bigbossman 

What he said. Sounds to me like your cones aren't adjusted in far enough. Pull it apart, check the bearings, and re-assemble. Make sure the cones are adjusted in far enough without binding.

If that doesn't do the trick take it to the LBS and have them check it.

Deanster04

Free hub body is just hanging on the hub and has nothing to do with wheel wobble. The FH will sometimes show a little wobble but that has nothing to do with the wheel itself.

MacG

If the freehub body was not securely mounted to the hub, you could potentially have some issues with wobble. When you tore it down and rebuilt it, did you remove the freehub body as well? It would have required a very large allen wrench.

Recheck the bearings. Maybe try slightly overtightening them and see if the amount of wobble changes accordingly.

Retro Grouch 

That's what I think too. It's common when overhauling a hub to require more than one try to get the bearing preload just exactly right.

The Great Stonk

the cones are not tight enough. if the axel came like that - leave it like that, alot of the time the cones are set slightly tight - so as the bearings wear in they loosen up just right.

its better to have the cones a tiny bit tight then a tiny bit loose. you wont notice slightly tight cones when riding, but youll notice loose ones.

MacG

I'll have to object. Bearings are designed to roll between the fixed cone and the moving cup to minimize friction. The balls are actually only in hard contact with both races at the same time for a relatively short angle of rotation. If you have them set too tightly, they will be rolling pinched between both races the whole way around instead of just at the point where they bear the weight of the bike. This will increase the wear because the bearings are under heavy load 100% of the time instead of more like 10% or 20%. If you go way too tight, then the bearings not only have to support the bike, but also have to physically stretch the axle to turn, which wears them out REALLY fast.

You're far better off dealing with a very small amount of play/wobble in the wheel than having the cones adjusted too tightly. Also remember that QR wheels will need to be set looser than nutted axles due to the pressure of the QR skewer actually compressing the axle slightly. Sheldon advocates modifying an old skewer to grab only the axle so that the cones can be adjusted while under a compressive load for an exact adjustment.

Loose = Fast, boys and girls. Just remember that too loose = wobbly wheel and problems. There is a small but very obtainable margin of correctness where wheel play is minimized but bearing life and rotational friction are at their optimum.

The Great Stonk

im not saying have them too tight, theirs tight, and too tight.

by just 'tight' i mean that turning the axel by hand with the wheel out of the bike can be slighlty notched, but not free spinning, as soon as the wheel is put in the bike and spun, unless its a super light wheel, you wont notice any difference and the wheel will spin forever.

personally i believe that, at least in off road use, that loose cones are more damaging then tight ones.

paul8f

Thanks for the advice.

Just a few other pointers regarding the problem; the freehub body was removed and cleaned during the hub overhaul and was bolted back securly to the hub (using a 10mm allen key if anybody wants to know). I'm very confident that the bearings and cones are adjusted correctly (it took me about 4 times to get it just right... the wheel now spins freely, there is absolutly no wobble on the axle, and all the outer locknuts are tight).

When the wheel is back on the bike it's a different story. The 'wobble' that occurs when horizontal pressure is applied to the wheel is difficult to describe. It doesn't feel like the 'rattle' you get with loose cones. Gentle horizontal force on the wheel doesn't do anything, but with firm pressure with both thumbs the rim will move a couple of mm and then kinda click back into it's original place with a notchy feel, when the force is removed. (sorry, this is the best way I can describe it..!)

The reason I still think it's the freehub body causing the problem is this:

1) I'm 99.99% sure it's not loose cones.
2) Not a bearing problem. The correct size and number of bearings are used
3) It's not the axle moving in the frame dropouts. Wheel is firmly secured (and the QR axle does not extend beyond the frame either side).
4) The bearings, hub, axle and cones look in very good condition

Does anybody know if there are bearings in the freehub body it's self? There must be because it rotates on the wheel when you back pedal or freewheel along.... I'm thinking that if there are bearings or some sort of bushing, that if this were loose/worn then the freehub body will be sloppy. And since the driveside wheel bearings are held in the freehub body then this could cause the whole wheel to move.

This is my theory. Anybody willing to back me up??

CBolt

The freehub could cause axle shucking only if the fastening bolt was not tight, and you say it is. The bearing adjustment would only cause the cassette to be loose.
Yes, there's a bunch of 1/8" or smaller balls in the freehub. Tighten the bearings with those two notches, visible when the axle is removed. I dont think anybody is currently mfg. the tool, but theres a dozen other ways to turn them. You might need the fastening bolt to be loose when you do the adjustment.

paul8f

Cheers for that. So you don't think that a free hub body with damaged bearings could be causing this problem?

By the way, what is 'axle shucking' ?

AndrewP

The freehub bearings will only affect the movement of the freehub relative to the wheel. The wheel bearings are the only ones that affect the movement of the wheel relative to the axle.

CBolt

If the freehub bearings were damaged your cassette would not be spinning. With bearings that small, there isnt much room for imperfection.

I guess shucking is a word I made-up to describe the motion/sound of a loose bearing.