Exclusive: BMW K100 Cafe Racer, “Optimus”

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BMW K100 Cafe Racer

We’re proud to present this BikeBound exclusive:  “Optimus,” a 1985 BMW K100RS cafe racer built by our new friend Stig Frydenberg from Norway.  We actually solicited Stig to feature this bike, as it struck us as such a clean, tasteful, and beautiful build.  Like many a good custom, the bike has that well-designed, almost showroom look, like it could have come this way from the factory in some (awesome) alternate reality.

Optimus Build Specs and Details

Here are the build specs from the Norseman himself:

“Frame is cut behind the rear shock, gearbox, frame, drive shaft and wheels are powdercoated. Lowered 2″ front, clip on steering, modified original front fender. Seat is molded from the original rear end. Battery and engine management is hidden under the seat. 7″ headlight, 2″ rear light. LED turn signals rear hidden in the tube, where the frame is cut. Coolant overflow is made from a RedBull bottle. Original instruments is changed to a modern digital one. Oil pressure light and coolant temp light is moved and put in to a BMW emblem. Ignition switch is moved to the top three. Two tone paint and cutting is done by Ola.”

We think the tank paint only accentuates the great lines of the bike, and the tail section fits the bike perfectly. Truly a beautiful piece of work, and most importantly, it’s clear that this bike gets ridden.

The BMW K100 as Custom/Cafe Platform

1991 BMW K100RS
Stock K100RS (Copyright 2004, Robert Odendahl)

The BMW K100s were built from the early 1980s to the early 1990s.  While the air-cooled (luftgekühlt) bikes tend to get more of the custom love, the 90-horsepower, liquid-cooled (flüssigkeitsgekühlt), fuel-injected K100 (and three-cylinder K75) has its own style and merits. The bikes came standard with dual-disc front brakes, single rear discs, Hella accessory plug-ins, and 460-watt high-capacity alternators. The K100RS had the tallest gearing of the group, and came stock with a sports fairing and low handlebars. Unlike some cafe racers, you can ride a bike built on the K platform all day long.

Other BMW K-Series Customs

In recent years, more K75 and K100 cafe racers have been popping up, such as The Therapist on BikeExif, Tatanka on ROTCR, this Estonian K75 on Pipeburn, and this K75 streetfighter on Silodrome. Like many BMW builds, these K-bike “kafe racers” tend to showcase the unique look of the engine, and the shape of the tank looks really great freed from the fairings.


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