Thanks Brian,
that explains it perfectly!
Tolerance on these rockstar pros is reallllllly tight⌠short of sanding off the paint, what are my options to get these bearings seated properly?
@mbs any tips?
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Donât you want them really tight? Whatâs the problem
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You could try gently heating the hub⌠If you donât want that bearing to ever come out.
The problem is that I canât even get them in! I feel like iâll break the hubs if i apply too much pressure
If thatâs true then thereâs something wrong with the fit, you put the bearing on the axle and pushed down with the hub?
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Yep, it goes on a tiny bit but then just gets stuck and wonât go any further.
Damn with full pressure? I would try another hub and bearing and if that still persists then there is a problem with the fit. You should not alter anything
Maybe try on a disassembled hub?
And try that bearing on a known good wheel to see if itâs too big maybe?
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The bearings came out of my rockstars, there was no issue with them there⌠will try seperating the hubs 
i just put tyres on all of them
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HmmâŚ
Yeah at this point my guess is either the hubs being assembled is distorting them somehow, or the hole is just undersized 
idk.
Hub is wonky sounds like
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I really feel like itâs just the thickness of the paint
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Bearings in the freezer and hubs are disassembled and sitting outside in the sun⌠will give it an hour.
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Just be aware that if you put it together successfully that way, it might never come apart again.
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Installing bearings with an arbor press isnât uncommon. Ideally Iâd prefer to see a light slip fit (maybe 0.0005-0.001" clearance) and some medium-strength bearing retainer instead, but a light to medium press fit is pretty common.
Just make sure that when youâre pressing them in, theyâre square to the hole in all axes, and only push on the outer race - Pressing on the inner race will cause the balls to indent the races, and itâll never run smoothly again.
My go-to ghetto method involves a couple of appropriately sized sockets and a vice.
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The other (much less convenient) option would be to take the hubs to a machine shop and have them correct the bores for you on a lathe (or mill). Hell, if I still had access to a lathe or mill, Iâd offer to do it for you.
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Well i think it will work with the heating and cooling after a little trial, but its going to take a significant amount of force⌠i was thinking about using a nut, bolt and some washersâŚ
Donât do that unless you have some way to apply force only to the outer race.
Iâve ruined quite a few bearings that way, luckily mostly trying to remove them so they could be discarded and replaced.
It may be worth trying a more drastic thermal differential - You can heat those aluminum hubs to a couple hundred degrees with no fear of damage (other than paint maybe), and freeze the bearings either in a freezer, or with dry ice. At my old job we used to use that method (using a torch and liquid nitrogen, up to a 700+ degree difference) to install a lot of bearings/bushings/pins/etc, and youâd be amazed how tight of a fit you can achieve with enough thermal differential.
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What are your thoughts on trying to lightly sand the paint off the hubs?