Be aware that there are 2 different 3 spoke K1100 front wheels. They have different dimensions and bearings. The K1100RS is a 3.50" x 17" rim whereas other K1100 wheels have a 2.5"" x 18" rim. The RS wheel uses a  25 x 47 x 12 bearing and a 25 x 52 x 20.6 bearing whereas the other K1100 wheels use a 25 x 47 x 12 bearing and a 25 x 47 x 16 bearing. The pipes and spacers (see each parts fiche) on each axle are different also. These differences can influence the position of the wheel on the axle and alignment of the brake disc rotors with with the brake calipers. The BMW parts microfiche will show you the differences between these 2 wheels. Hope this helps.

Anything is possible with access to a machine shop and someone willing to chuck up a coupla pieces of aluminium and fab the required spacers for you. Keep in mind the way the discs you'll use are offset to the wheel/calliper spacing you'll need. Also, as mentioned prior, determine whether the bearings will fit the axle - or whether you can obtain bearings of the appropriate dimension - you decide to use and whether that axle will fit through the available space in the K1100RS 17" wheel (steer clear from a K75S/K1100LT wheel, the 18" version, due to less tyre choice). You have entered the custom zone. Be not afraid.

If you plan to have ABS then you also need to figure out how to configure that to work.

Two Wheels Better wrote: (steer clear from a K75S/K1100LT wheel, the 18" version, due to less tyre choice). You have entered the custom zone. Be not afraid.

Are the K75s and K1100LT front wheel the same wheel?  Haven't had the two side by side, but with one(1100) being on four pot calipers and floating disks and the other(75) used non floating disks and twin pots I would have thought they'd be different wheels (also 16v/1100 forks further apart, different disk offsets etc)

Al

According to Anton Largiader's webpage on BMW alloy wheels (http://www.largiader.com/parts/wheels.html), the two wheels are similar in some aspects an different in others.  Both are 2.5x18 however they are different part numbers. suggesting other differences -- 36 31 2 312 809 for the K1100LT with 305mm floating brake rotors and 36 31 2 310 734 for the K75 with 285mm fixed brake rotors.  Anton's page does not list brake rotor offsets but those might be similar also.  The page does say "K75 and K1100LT used bias-ply tires and had different dimensions" which is. a statement that might only refer to the tires and not the rims.

I should think that if one was to go to the trouble to swap an S1000 front fork setup to an old K bike, the easy answer is simply to source an S wheel, axle & spacers, callipers & brake discs. To 'sort of' match its design use a K1200RS or R1150 5x17 five spoke rear to match. There are places online that flog bearings/spacer kits to adapt non K forks to K steering head dimensions. FWIW.

Thanks everyone! To answer some questions, it’s the 3.5x17 from an RS, and I don’t plan on running ABS. I already have a triple clamp for the set up and I’m looking just to matching wheels front and rear.

I’m quite surprised no one’s ran this set up after doing hours of research if anyone’s done it Before.

Maybe no one has done it because maybe possibly the length of the S1000 forks puts the bike at the wrong stance and affects handling.  I don't know; I'm just guessing here.  Modern forks aren't as long as vintage forks generally.

robmack wrote:According to Anton Largiader's webpage on BMW alloy wheels (http://www.largiader.com/parts/wheels.html), the two wheels are similar in some aspects an different in others.  Both are 2.5x18 however they are different part numbers. suggesting other differences -- 36 31 2 312 809 for the K1100LT with 305mm floating brake rotors and 36 31 2 310 734 for the K75 with 285mm fixed brake rotors.  Anton's page does not list brake rotor offsets but those might be similar also.  The page does say "K75 and K1100LT used bias-ply tires and had different dimensions" which is. a statement that might only refer to the tires and not the rims.

The wheels are completely different in the center where the rotors mount to the wheels. Rotor and caliper positions are different too. Some people (like Special K Larry for example) have built custom caliper brackets to install the K1100LT front wheel, rotors and calipers on K75 forks.

But I swap in K1 or K1100 forks and triple tress on my K75s so no custom brackets are required. The later steering stem is smaller in diameter so you no longer are using the fluid block damper. With bias ply tires that makes a K75 "twitchy" at very low stop-n-go speeds but that's not an issue with a radial front tire.

I think Anton was referring to different bias ply tire sizes. K75s/K100s came with a 110/90-18 while K1100LTs came with a 110/80-18.