R100R to RS.... how much do i need to raise the rear end?!?

[andrewinuk]

OK... this is probably not the first question someone usually asks during this transformation but i have made a few modifications that i want to keep..... primarily a sharper steering angle compared to standard.

when i first got my 1992 R100R i didn't really like the way it handled so dropped the triple clamps down the forks so the legs were the same length as my previous RS, a move of 38mm, added some clip ons and now had the bike exactly as i wanted it with it's S style bikini fairing.








but as i now have a 900ss for trackdays the R100 can be focused more on touring..... which could only mean one thing, yes an RS fairing!

trouble was that:
1. the clipons didn't fit in the fairing
2. the RS bars do not allow the forks extended above the triple clamps enough even with an extra set of bar raisers
3. i have an expensive and much loved top spec wilbers rear shock set at R100R length that i am compelled to keep




so what to do?!?

easiest option seems to be to raise the rear by extending the shock mount by ¾ of an inch to get to GS dimensions (and wear out my drive shaftL ) to set the bike up Boxer Cup style a little further off the ground. there seems to be 2 options (as i didn’t want to shorten the forks and it is cheaper than raising the engine if i do more trackdays on the BM)

1. extend the shock mount with some welded tabs
2. fabricate a bolt on extender



i am in good hands with the engineering but i wanted a more maths focused person to advise on how high the rear needs to go to get RS style angles on the steering as i am rubbish at that sort of thing..... any thoughts? Any other options??