I have been working on a sealed bearing conversion for a friend.
He wanted to convert his Puch skinny wheels to sealed bearings.
I popped out the bearing cups and measured the hubs. They were 29mm. They do not make 29mm bearings but they do make 28mm. I got some .5mm shim stock to wrap the bearings in. I cut a strip of the shim stock and stuck it around 1 of the bearings and pressed it it. then i measured the inside of the hub between where the 2 bearings would be. I made a spacer to fit in-between these two bearings. This is very important because its what takes the stress when you tighten the axle. After i made a 12mm ID spacer, I put it into the hub and pressed the other bearing in.
Then I put the axle thru and fit the brake plate on. It needed to have a spacer between it and the hub. I used stacked washers to space it perfectly. Once I found the perfect spacing I took out the washers and measured them with a caliper. I than made a spacer that was the same and the stacked washers
After I made a spacer I put it together again. This time I put it on a maxi fork and used washers to space it correctly for the fork.
One I got the wheel perfectly centered I took the washers out and measured then and cut spacers with 12mm ID stock.
Once I had all the correct spacers made I bolted it up and spun it really good. Its perfect!
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