Boxerworks.com

1984 R100S

So I've decided to go back to standard size tires on my bike. I had shimmed my wheel over to make room for a wider tire. Silly me. When I put back in the standard top hat shim, will I need to make any adjustments to the swing arm bearings in order to have the correct geometry?

When BMW introduced the wider 10.7 mm spacer they stated the the wheel offset between front and rear should be checked and adjusted to not exceed 4mm.

Zombie Master wrote: ↑Fri Nov 27, 2020 2:02 am 1984 R100S

So I've decided to go back to standard size tires on my bike. I had shimmed my wheel over to make room for a wider tire. Silly me. When I put back in the standard top hat shim, will I need to make any adjustments to the swing arm bearings in order to have the correct geometry?

In theory, no, unless they were adjusted to offset the swing arm when the shim was changed in the first place... or to put it another way, maybe... It's easy enough to check, the space between the swing arm and the frame should be equal on both sides.

Rob

We used to play with wheel bearing shims and altered top hats to allow fatter tires to clear the swingarm.
Had to, it looked so cool!
Then we would adjust the swingarm bearings to try to give front and rear tires the same centerline.
After all that, we concluded handling, stability, and lap times did not improve, if anything, they deteriorated.
But, hey, it looked soooo cool!

Just curious...Does anyone know what size tires Reg Pridmore was running on 'ol #163 when he won at Daytona in '76?

The "King of the Boomers" article mentions that the front rim was a WM-4 (2.65") and the rear rim was a WM-5 (3.00"). Not sure of the size tires that could be mounted to these rims. I think the pictures show that it was twin shocks, so I suspect that limited the size of rear tires...certainly the standard swingarm limits what can be easily removed for tire changes.

Kurt in S.A.