Wheel nut crushed my bearings

Any problems? I’ve probably done about 150 miles before this happened.

They’re wrong.

Bearings need spacers, especially if you’re getting side loads torquing the bearings like a big tall 8" MBS wheel certainly will.

You probably talked to a Grom who 's just there to answer the phone or something. Either that or they have some dumb business reason why they don’t want to do spacers and are trying to push that as acceptable.

Insane that a company selling $600 completes wouldn’t be using bearing spacers.


go to Aluminumspacers.com You should be able to find a the size of spacer you need there.

Tip: I use the thick wall spacers and they work much better than thin wall.

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Anyone know what size spacers to run on MBS hubs? Not sure how to measure it since it’s an internal measurement

Get a bunch of washers and stack them between the bearings then take them out and measure them with caliper or a mic. Start with too many and remove them one by one until they allow the bearings to seat fully.

You didn’t just happen to have your wheels off your bearing setup?

It’s really nice that you take good pics of things people ask, I know a lot of work goes into that so yeah Cool dude thanks for being helpful.

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I actually had a picture saved from doing the Fatboy 3:1 installation write up. It sufficed for the purpose :slight_smile:


Good idea! Thanks!


I’m sure the Rockstar have the same width as superstars

Could probably just order a Trampa axle refresh kit…

If you have a caliper just measure between the outer races of the bearings, hold something against the bottom bearing, then subtract the width of the bearings and voila, that’s your length of the spacer.

I have a question for spacer experts, on my trampa hubs there are shorter spacers (16.5mm) with 2mm rubber o-rings between the bearings. Then I filed down custom spacers (about 17.5mm) so I could crank down the axle nut with free spinning bearings and rattle-free. But I think this was not good for the bearings, they sound awful and crushed now after a short time, need to replace them.

So my question is, is it better to have a tiny gap between spacer and inner races of the bearing? It seemed the tight fit is a bearing killer at least in my case.

Hey Rich, are the bearings seated all the way? So when you move the hub you don’t hear the outer races clanking back and forth? If you have any play from the outer race not fully seated on both sides they may clank…

Yes they are seated all the way, bearings and spacer are like one unity, absolutely no play at all, but some wheels still wiggle because the bearings have play inside the spokes :rofl: I’m thinking about using o-rings again because I can’t fix the rattling anyway.

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You need to seat the bearings in the “spokes” so they have no play. This could be part of your cause Bro :thinking: You can use glue/loctite, I cowboy’d my superstars up with some plumbers teflon tape to make them friction fit. Another solution might be to use C3 bearings, but that is just a guess…