My '91 K100RS has the original bars which are, to my taste, a little 'sit up and beggie'. I'd like to get close to the R100RS, but fairing and tank clearance places a limit - so clip-ons are out.

Did the K1 have lower bars (RealOEM suggests they're the same)?  Are the earlier K100RS bars lower, or just narrower?

Any suggestions for dropping 20 / 30mm ?

Please post a side photo of your moto showing us what it has now. The RS bar tends to place the rider in a forward position, not a vertical position. My moto has a Flanders sidecar bar. It's about half and inch lower (2.5"), has two inches less pull-back (2.75"), and is an inch and three-quarters wider (27") than Flanders' R90S bar. If you're looking for a forward position that isn't full tuck, that should give you one depending on your arms' length.

K1 'bars are flatter and rise barely 2", but are no wider than RS 'bars. RS 'bars rise over 3" but drop down at the ends faster and are swept back but only a bit more. They are both approximately 26" or 670mm tip to tip. K1 'bars are definitely more leant forward and with a different wrist angle. I have a set of both in my garage. I'm going to use the K1 version on my K1100RS.

These are the bars on my bike ('91 K100RS 16V).





I believe they are original fitment. Overall width, to ends of grips not weights, is 620mm The lift, c-c, from the clamp to the highest part is about 70mm. They are constructed in three parts with a centre tube thru the clamp and two ends, with rise and bend out, welded to it.


To put some number on the camparison with an '81 R100RS, I measured the heights of bar and seat to the ground while on the centre stand (block under airhead rear wheel to floor the front). Bars are measured to centre line midway along the grip.
K100 bars: 1070mm, seat 850mm.
R100 bars: 1000mm; seat 860mm.
Clearly suspension movement when on wheels with rider will change these numbers but the essential takeaway is the bars on the K are perhaps 80mm higher than the R. Don't think it's practical with fairing and tank to get more than 30mm down.

TWB: in your pic, is the fitted bar from a K1? Is the K1 bar a single length of tube?

yep, K1 'bars bought new from BMW mounted to the '96 K1100RS, & OEM K1100RS 'bars from a '93 model parked next to it (out of view).