>>1921910the bearing nearest where the axle threads into the crank would be easier to make a standard size as there is more room
most variance is the bearing on the outer end of the axle, this part of the pedal is thinner so often bushings are used here
the pedal op mentioned uses bushings on both ends,
bushings are not so well suited to full rotation or high speeds, but they offer a large surface area in a small space, and perhaps more importantly they are cheap
