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bearing adjustments for lower-end hubs(8 posts)

bearing adjustments for lower-end hubsxxl
Aug 27, 2003 7:01 AM
I've a question that's been bugging me for awhile, so I'll let the board take a crack at it. When adjusting lower-grade hubs (e.g. Sora and below, and/or older equipment), I find that there isn't always that point of "perfect" adjustment that you can get with the better hubs; it'll be either a bit tight, or a bit loose, and no amount of sweating over it seems to make much difference. Part of that, I suppose, is due to the wider tolerances on bearings, axle "roundness," etc. (it is why the high-end stuff is so, well, high-end, right?)

So, what's your preference (and why)? Run 'em a bit loose (maybe a slight but definite side play at the rim), or a bit tight (a slight but definite binding in at least some of the axle's range of rotation)?
I vote loose. nmOldEdScott
Aug 27, 2003 7:34 AM
Check bearing size uniformityContinental
Aug 27, 2003 7:45 AM
I've frequently found 2 or 3 out of the 20 ball bearings that were measurably different in size. I have a steel plate with a hole that a properly sized bearing fits through. If the bearing doesn't fall through the hole, or if the bearing is noticibly smaller than the hole, I discard it and find one with the proper size to replace it.

I used to adjust hubs just a little bit loose until I started riding hills and hitting speeds close to 50 MPH. I don't want any wobble now, so I err on the tight side. Still, all my wheels will pendulum back and forth a few times when coasting down with no load.
re: bearing adjustments for lower-end hubsgtx
Aug 27, 2003 8:47 AM
Ultegra and down Shimano hubs tend to come a bit tight out of the box. Usually I'd leave 'em like that for a few hundred miles and let them break in. After that, you want to check them adjust it a tad loose, but so that there's no play once you clamp down the qr.
Loose, and here's the explanation of whyKerry Irons
Aug 27, 2003 4:11 PM
You want to adjust any bearing to eliminate play without binding. If you have to choose, you accept a little play to avoid the binding. If you have binding, there are EXTREME forces on the cup, cone, and bearing - binding is the bearing being forced through an opening that is too small. Given the hardness of all the parts involved, this forcing is a recipe for eroding surfaces and pitting either the cups, cones, or bearings (or all three). The idea of "breaking in" a loose bearing system is totally bogus. You can break in a sealed bearing system as the seals settle in and are worn down, but you cannot break in a hardened metal component. Those who advise this practice are giving really bad advice.
Loose, and here's the explanation of whyxxl
Aug 27, 2003 6:36 PM
Interesting point, the extreme forces on the bearings; these would be more than, say, the brinneling forces that might happen on a loosely-adjusted hub that just hopped over some road crap? (BTW, I'm not trolling; this is one of those questions I ponder on long solos, so I've thought about it a lot.) For the record, I run 'em loose, mostly because I'm too lazy to readjust after X miles, and a binding bearing, even a cheap one, just seems wrong.
Forces of evilKerry Irons
Aug 28, 2003 5:12 PM
You bet I'd rather have a good hub that never had to be adjusted with play or binding, but given the choice . . . I'm guessing that the amount of play in a hub, and the fact that there's grease spread all around in there, doesn't allow much accelerate - BANG to happen when your wheel becomes airborne. And even in that case, it is an extremely rare event compared to forcing bearings through a too-tight opening every revolution of the wheel.
Forces of evilxxl
Aug 29, 2003 5:24 AM
I'll buy that. (nm)