How to shim the cush drive

The sprocket carrier is not rigidly coupled to the rear wheel; it "floats" with a piece of hard rubber taking up the slack. If there is too much slack, you'll feel excessive drive lash when applying and releasing throttle. Adding shims takes up some free play and reduces the lash.

With the rear wheel off the bike and properly supported (be mindful of the brake rotor on the other side) wiggle the sprocket carrier off. If you've never taken it off, gunk may be holding it on. Just twist and wiggle, and it'll come off.

Now, find a suitable material for the shims. I use margarine tub lids; Jeb has used milk bottles. Anything similar should work pretty well. Cut out 12 rectangles, each roughly 5/8" x 1 1/8". When I first did it, I used two in each crevice, for a total of 24. Since then, some slack has come back, so I added 12 more, for a total of 36, or 3 at each crevice.

Now simply insert a piece into each of the 12 crevices between rubber and steel.

Put the sprocket carrier back in place (it may be a little tight now; simply press and wiggle) and reinstall the wheel. You should notice a much smoother ride.