repacking wheel bearings

[handlebar]

Within the first year, I began to see oiliness on the front hub of my Radmission. Grease is 75 to 98 percent oil. To seep past the seals, oil must have come out of the mix. That could result in dry bearings.

With a caliper, I found I'd need a 15mm wrench for the cone. With feeler gauges, I found that it couldn't be more than 3.5mm thick. Amazon's first suggestion was labeled a pedal wrench. However, a reviewer posted a photo showing a caliper on his, reading 1/8 inch. That would be 3.17mm. I ordered it.

I looked online for any advice that might be contrary to my old experience. An Irish professional said always to replace balls. I hadn't thought of it, and it made sense. If you have play, it probably means your balls have worn smaller than the races were designed for.

Internet sources said adjusting bearings on a quick-release axle was difficult. Tightening the locknut would cause the axle to rotate in the cone, changing your adjustment.  If you got it perfect, clamping the axle between the forks would squeeze the axle slightly shorter. The bearings would be too tight. You'd have to remove the wheel and adjust the bearings slightly looser.

One source said he'd made spacers to clamp the axle with the skewer off the bike. I liked that idea. I can feel drag, smoothness, and play better if I move the axle with my thumb and finger than if I move the wheel on the bike.

The wrench was 4mm thick, 26% thicker than the reviewer had measured. I had to do a tedious job of grinding.

I removed the lock nut. Then, for the first few turns removing the cone, I had to use two wrenches, with the thin one holding the opposite cone. I realized the manufacturer had adjusted the bearings with axle and cone threads dry. I got them greasy taking the hub apart. Before assembly, I degreased the cone and axle. Dry, the axle threads had a rough black coating.

That seemed to be the secret to adjusting bearings: friction would keep the axle from turning within the cone as you screwed down the locknut on greased threads.

I measured the balls at 6.34mm. Quarter-inch balls would be 6.35, but I'm sure 6.34 is well within the margin of error for my caliper and the bearing manufacturer. After 750,000 revolutions under my weight on bumpy surfaces, the bearings had no measurable wear.

For assembly, I slid a foot of vinyl tubing over the axle so I could pack the bearings without getting the threads greasy. Flexible tubing tends to tighten when pulled. I had to grab the locknut on the other end so I could twist the tubing as I pulled.

I used a stack of 3/8" flat washers on each end of the axle as spacers to test my adjustment with the skewer compressing the axle. I felt a little roughness when I turned the axle-skewer assembly, proving that skewer pressure really does make an axle shorter. The bearings passed the test after I unscrewed the cone 30 degrees (an hour on the clock).

With seals and dust caps in place, I washed the hub and disk because I want to know if there's seepage in the future.