Hi Mr BMW R 1100 R -
Ohlins Has both front and rear in a S46
(others reduce Front size to S36 Body) So Prefereed Larger Piston, Large Valving,(has plusher feel)Shock body,Spring Choice to Others-
The Frt S46ER1 and Rear S46DR1LS are the most common choice.
The more popular rear has REMOTE HYDRUILIC PRELOADER(an Easy TURN KNOB for Spring Preload Changes , REAR ALSo has Optional EASY HIEGHT, Length Adjust, (while still on bike).
They may match the bike the best,
The rear is Offered also in a NON-REMOTE PRELOADER but then it's pretty hard to make changes to spring preload on the fly.
I'll look for pics-
Hope this Helps!