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pressfit bearings + axle how can that work
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I had to change my pressfit bearings again and still do dot understand how that system works.

In the old days with cone-bearings the axle position was defined radially AND axially by the bearings.

In the system with pressfit bearings where you enter the axle afterwards the axle position is only defined by the bearings in radial direction.
Axially it is defined by the cranks touching a spacer. In my case, it is a plastic spacer (one left and one right).

There is thus a friction between the cranks and this spacer. If you pedal for example hard on the right side, it seems to me that the crank with the axle is pushed inwardly to the left against this spacer, causing friction.

This friction must be neglegible because otherwise this construction would not exist. Is it really neglegible? Does the axle center itself during pedalling such that the cranks hardly rub against the spacers? I never understood this. Thoughts?
Last edited by: longtrousers: May 21, 20 4:50
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Re: pressfit bearings + axle how can that work [longtrousers] [ In reply to ]
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After posting I looked at the bearing again and I think I understand now. I could delete my post but I think I can't delete the thread so I leave it. Maybe it is interesting for someone anyhow.

It appears looking very precisely, that the sealing ring of the bearing is sitting on the inner bearing ring. This bearing ring rotates with the axle. So the whole system consting of inner bearing ring, sealing ring, spacer, crank and axle do not rotate relatively to each other, and a possible axial force (caused by pedalling) is absorbed by the bearing (those radial bearings can also absorb a certain axial force).

So the sealing ring has not only sealing purposes in this system (it has to consist of metal instead of plastic like a conventional sealing ring) and should not be omitted.
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