Form Follows Function On This Stunning Custom-Built BMW R100GS
Meet Gregor Halenda's vision of the ultimate BMW adventure bike.
Halenda is a professional photographer who started building custom bikes in 1998 after totaling his BMW R90S in a crash. He had just purchased a beautiful one-off polished aluminum fuel tank for it and didn’t want it to go to waste. A friend taught him machining and welding basics and he turned the bent BMW into a cafe racer that looked as good as it performed. Form and function had to merge on the project and that’s been the motivation behind his seven or eight builds since. One of his notable collaborations was the AWD KTM 950 Super Enduro built for REV’IT!. “My feeling then, and now, is that adventure bikes are the most relevant and interesting bikes to work with,” Halenda said.
BMWs have been a passion for him since he was a kid. A neighbor’s R69S clocked 200,000 miles, which impressed him, and when Gregor’s father passed a few years ago he inherited his BMW with 294,000 miles on it. “[Older] BMWs are over built, simple and smartly designed,” he said. “I love the sound, the maintenance-free drive shaft and the look of the cylinders in the wind. They’re cool.”
He first saw this R100GS on Bike-urious – a website that showcases unique motorcycles for sale. The previous owner, from Canada, modified the frame and built the tanks. Once again, it was the lovely polished aluminum tanks that started the wheels turning. “The tanks were the thing I loved most of all as they looked just like the sketches I’d done for REV’IT! but didn’t use,” he said.
A buyer from California snapped up the bike before Halenda could. A couple months later, Halenda followed up with the new owner to see how he liked it and learned the guy was having trouble getting it titled, and that there were mechanical issues. He sold it to Halenda.
The bike turned out to be a bit of a heap. The engine burned a quart of oil every 100 miles, the brakes were marginal, the suspension worn out and the electrical system a mess. Even the tanks were more form than function: they leaked water into the fuel.
In the last year, Halenda has remade the bike top to bottom, front to back. He rebuilt the engine from the crank out, modified the frame to reposition the bodywork, machined a custom stem to fit the 450SX triple clamps, and swapped in 48mm WP forks from a KTM 690 Enduro R. The bike now sports over 11 inches of suspension travel, an increase from the previous 9 inches. The BMW also features Brembo calipers with custom stainless-steel brake lines. In the rear, he replaced the driveshaft, rear end and brakes.
Halenda’s decision to run a large 140/80-18 rear tire forced him to cut the swingarm apart and modify the mount. “I wanted to run Golden Tyre’s GT723R Rally Raid tires but in order to fit them, I had to cut apart the swingarm and machine a new mount out of billet and then weld this in. This mod took several days but allows me to run the largest wheel/tires ever run on a BMW,” explained Gregor.
The brake and shift levers are all custom fabricated with precision needle bearings and new linkages. And the tanks got attention as well: Halenda put in new petcocks, fuel necks and caps, and modified the mounts. Together, the three tanks hold a combined eight gallons (30 liters) of fuel.
Fuel capacity speaks to the bike’s purpose: long-distance exploration without sacrificing high-speed, off-road fun. Halenda understood that achieving those often-contradictory goals in a single bike meant shedding as much weight as possible. That was factored into every design decision. The wheels, for example, were built by Woody’s Wheel Works in Colorado with lightweight in mind.
“The single most important thing to improve on is weight reduction,” he said. “I got the weight of this bike down to 400 pounds, with most of that weight coming off the wheels, the most important place to take off weight. Every pound of rotating weight is worth about three pounds of static weight. The wheels Woody’s Wheel Works made for me knocked off 20 pounds of rotating weight and the bike feels like its lost 100 pounds.”
According to Gregor, the bike is now reliable and the handling is much quicker and lighter. “I have geared it down in the back with the lowest rear drive that BMW makes so the acceleration is pretty quick and the torque is really strong. Right now I’m working on the engine with the plan to get another 10 rear wheel horsepower out of the bike. This will give a good power to weight ratio.”
As well thought out, complete and beautiful as this R100GS is now, it’s really a test mule for Halenda’s next build, which he says will be “the ultimate BMW adventure bike, the bike my father would have wanted when he was 25 years old. Light, powerful, well suspended, simple and exceedingly beautiful. A bike you’d like to look at as you ride around the world.” Target weight on that bike is below 350 pounds, a goal he says is achievable by starting with a custom frame and lighter bodywork.
“In my mind, adventure bikes are just as amazing a platform for a custom as anything; better in my mind,” says Gregor. When the next bike is fully developed, this one will go up for sale, he said, so stay tuned if you share his vision of what constitutes a great adventure bike. We’ll sure be following!
Halenda’s Custom BMW R100GS Mods
Base Bike: | Mid 90’s BMW GS |
Engine: | Early 80’s BMW R100RS big valve |
Head Work: | Baisley High Performance |
Body/tanks: | Made by the previous owner from Canada |
Frame: | Cut, braced and the engine is raised and tipped |
Driveshaft: | R1100GS/R100GS hybrid |
Swingarm: | R1100GS cut, sectioned & shock mount repositioned with billet mount to allow 18” tire |
Rear end: | R850R 37/11 (lowest possible) |
Brakes: | Brembo |
Suspension Travel: | 11 inches (279 mm) |
Forks: | 48mm WP upside-down 2018 WP forks from a KTM 690R |
Triples: | KTM 450SX |
Bars: | ProTaper CR High |
Wheels: | Woody’s Wheel Works custom billet hubs, Superlight & Superlaced with two part disk rear hub laced with double butted spokes to Excell A60 rims |
Tires: | Golden Tyre GT723R Rally Raid in 90/100-21 front and 140/80-18 rear |
Tubes: | Tubliss |
Grips | Renthal half waffle |
Shift/Brake: | Handmade from 304 stainless on precision needle bearings |
Footpegs: | Fastway – adapted with custom hardware |
Exhaust: | 304 Stainless – handmade |
Electronics/Ignition: | Euro MotoElectric (EME) charging system and ignition |
Dash/GPS/Gauges: | Trailtech Voyager Pro |
Photos courtesy of Gregor Halenda
Notify me of new posts via email
Absolutely stunning machine with the specs to back it up. Bravo!!
Lovely and looks like a hoot! His next build sounds great! If he uses a HP2 as a base the weight reduction diet is going to be very interesting to see with a goal of less than 350 lbs.