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Rear hub sealed bearings

Old 12-05-23, 06:18 AM
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Rear hub sealed bearings

I would like to know more about sealed bearings in the hub.

1.
I removed the axle and this is what I have:

both bearings spin easily but one is smooth on disk brake side and you can feel roughness on the other behind the freehub (like the grease has been washed out)







2.

the axle spins smoothly in the freehub.

there are 2 more bearings in the freehub, is that correct?

how would you remove axle from the freehub to access the bearings? (I wont do this, I am just wondering about the desing of all this)


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Old 12-05-23, 06:34 AM
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What brand/model/info do you have for the hub?
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Old 12-05-23, 07:35 AM
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Two bearings in the freehub is common, one at each end.

Sounds like the sealed one in the hub drive-side is worn. Bit surprising as itís probably the one thatís best protected from the elements.
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Old 12-05-23, 10:13 AM
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Originally Posted by utoner34
there are 2 more bearings in the freehub, is that correct?
Usually.

how would you remove axle from the freehub to access the bearings? (I wont do this, I am just wondering about the desing of all this)
You persuade it out. Put in an open vise or balance it on something where you can support the edges of the freehub (red boxes). Using a soft hammer, tap on the other end of the axle to drive it out of the bearings. You donít want to go all John Henry on it. Gentle persuasion is the key.
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Old 12-05-23, 01:26 PM
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Originally Posted by choddo
Two bearings in the freehub is common, one at each end.

Sounds like the sealed one in the hub drive-side is worn. Bit surprising as itís probably the one thatís best protected from the elements.
That side gets the force of gravity pushing/pulling (however you want to look at it) down and the pull of the chain (when pedaling) forward.
NDS just has gravity.
IME, DS cones are more prone to wear/pitting etc.
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Old 12-05-23, 03:58 PM
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Sometimes the LH axle end has an 8mm hex socket allowing the axle to be held. Then a wrench on the RH axle end cap that has those two flats. Good chance that end cap will unthread and the axle be able to be slid out of the FH body from the backside.

generally the bearings in the hub shell are fairly easy to remove but the FH body ones can be really tightly pressed in. In those cases I'll warm up the FH body in the oven to about 250 degrees to expand it. I'll also replace all the bearings when I do these jobs. For the cost VS the hassle to redo any sooner than needed it's worth it IMO. Andy
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Old 12-05-23, 04:28 PM
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Originally Posted by Andrew R Stewart
In those cases I'll warm up the FH body in the oven to about 250 degrees to expand it.
Doesnít that also heat the bearings up just as much, or is it different material/coefficient of thermal expansion?
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Old 12-05-23, 04:43 PM
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Originally Posted by choddo
Doesnít that also heat the bearings up just as much, or is it different material/coefficient of thermal expansion?
Bearings themselves are usually steel, which has a lower coefficient of thermal expansion than the normal aluminum body.
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