Bicycle Mechanics - Question about rear hub + mas.
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05-19-06, 01:33 AM
When my rear wheel's moving fast enough, the distance between the hub and the cassette changes very slightly resulting in what looks to be an in-out motion with respect to each other. I cleaned the hub out and regreased the bearings, and now it's barely noticable but still there. I was thinking it might have to do with the rear derailler since the bolt that it mounts on (in the rear dropout) was stripped so the rear derailler isn't torqued down on the rear hangers by itself (the wheel bolt really torques it down). I was still wondering if it's just the stripped bolt or a worn hub?
I feel like a newb... :D
05-19-06, 03:04 AM
Ahh i've noticed that on one of my bikes. Does the cassetee it appear to be 'wobblying' back and forth when the wheel is spun? I would like to know the answer to this aswell! :D. I notice it on a lot of lower end Trek's.
05-19-06, 03:22 AM
Yeah, wobblying sounds like a good description! It might have something to do with the bolts being too tight since I noticed it more when I torqued down too much on the nut on the bearing cup? if that's what it's called.
edit- I played around with different nut pressures on the hub, and repacked the bearings, but the problem persists. The thing is, it looks like it's maybe a few hundreths of an inch deflection between the cassette and hub, which could be within tolerance for low-end bikes (70's schwinn traveler here)? They just don't line up flush. Of course I tried taking the cassette off to tinker with, but it's been on there for ~ three decades and isn't going anyplace easily! ;)
05-19-06, 07:10 AM
You have a freewheel, not a cassette, and that wobble is pretty typical.
05-19-06, 07:13 AM
This happened with lots of freewheels, and usually just meant that their threads were machined slightly off-kilter so that they wobbled side-to-side slightly with each revolution of the wheel.
With a cassette hub, it means that the freehub body is not perfectly in line with the axis of the hub. The freehub body attaches to the hub with a 10mm allen bolt. The wobbling could mean that the threads in the hub body were machined at a slightly off-kilter angle. Or it could mean that the freehub body isn't tightened down properly into the hub, or was seated incorrectly when it was screwed into the hub.
I've had this problem before, and it was solved by disconnecting and then reconnecting the freehub body to the hub itself. To do this, you'll need to remove the axle from the hub, to get the 10mm allen key inside at that bolt.
05-19-06, 08:00 AM
It's called the "Freewheel Dance" and is very common.
Don't worry about it it will not affect the performance of the bike.
05-19-06, 10:24 AM
Thanks for all the info everyone! I didn't even know there was a differnce in the name (cassette vs. threaded freewheel). :)
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