The alloy ST4s wheels are heavier. I have the exact weights somewhere (search on Shazamm's posts) but I seem to remember that the 5 spoke allys are only a pound or so lighter than the 3 spoke brembos. I'll let you know about the ST4s rear dimensions in a week or so. I was hoping it'd be a drop in (with bearing changes) but I am now having some doubt. The front is easy, new bearings and a machined monster speedo drive, Job done.
Rob,that bearing change isn`t that straight forward,if you look at the "customer race bikes" the rear spindles are the larger size,so one option is to machine the swingarm holes instead,I know baines have done this before.This would be reasonably straight forward and then use later monster chain adjusters.
Graham, Why do you say "that bearing change isn`t that straight forward"? Do you have some knowledge of particular issues? If you do, I wouldn't mind a call to chat it over.