Maybe its my age. Cannot get my head around working out offsets.

Have a 1998 (sc33) CBR900RR. Putting the VFR800 (1999) sssa in it. I read the VFR800 rear wheel had a 19mm offset. But doesn't it make a difference because its going in a CBR frame ?. My mate is milling off all the sssa meat from the RH side ( Opposite from sprocket side ) and putting an extra bearing etc on the inside of the arm . Taking nothing off the inside of the frame as I prefer this..

Havnt decided what wheel to use yet, but please if anyone can explain what offset I have to start with and how to work it out for whichever wheel I choose that would really help

 

My understanding is that wheel spacers are used in the conversion to make sure that the center of the wheel is on the centerline of the frame, while also making sure that the sprocket and other hardware also lines up. I don't know exactly what size spacer is used (it depends on the bike) but if you already have all the parts you should be able to mock it up and measure it. The low-tech option is to go and get a bunch of shim spacers (not standard washers, but actual spacers) from the hardware store, and to use those for mocking up. Make sure to torque it down and everything so that your measurement doesn't wander on final assy

Once you know exactly how many shims are needed, you can measure/calculate the required thickness. Then it's just a matter of searching out a wheel spacer with the required dimensions. If your friend has a mill you also have a few options to trim down a few thou if needed. If it's binding up you need to take more off, and if it's loose, you've gone too far

Obviously there's a bit of guesswork, but so long as you can get the wheel snug, smooth, and play within spec, it should work. Make sure to post pics of the results. I've always wanted an excuse to do something similar

Good luck