Old 07-16-18, 08:20 AM
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Originally Posted by toast3d View Post
I have often seen the advice that one ought to keep hubs slightly loose when repacking them with fresh grease and new bearings. This is because they say that the axle will be compressed when the quick release is clamped down.

This doesn't make sense to me.

The lock ring should prevent that. You can clamp down the wheel as much as you want, but the force of the quick release is going to be hitting against the outer nut (lock ring), which is stopped by the cone that has been rotated out into it. That's the whole purpose of the lock ring. It ensures that everything stays in place exactly as you have adjusted it.

I just don't get it. Surely the force of the quick release can't be enough to overcome the threads on the axle, which it isn't even pushing against in the first place anyway. So why do so many people advise to keep the hub slightly loose when repacking it?
It depends on whether you have a solid or hollow (skewer quick relase) axle.

On a solid axle, the the tightening wing nuts are pulling the axle against the frame. The locknuts will prevent axle expansion, when the wheel is tight in the frame.

On a hollow quick release axle, the skewer pushes the frame against the locknuts. The locknuts will transmit this force to the cones, as the skewer is tightened. That's why it's necessary to compensate for this force when adjusting the bearings. Excessive over-tightening will push the axle until it starts bending.

The need to compensate for locking the cones in place isn't limited to hubs. The same is true for headsets. Bottom brackets are the exception. The adjustable cup is pulled away from the spindle, when the lockring is tightened. You want to slightly overtighten the adjustable cup with the expectation that tightening the lockring will bring the adjustment to it's "perfect" position.
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