BMW R nineT Chopper.
The most incredible motorcycles come from the most difficult concepts.
When we delivered an R nineT Racer and a wild idea to Nigel Petrie of Engineered To Slide back in 2019, this inspiration became one serious challenge that he never backed down from.
He unboxed the bike and tore it down to start the build — only keeping the engine, rear drive unit and rear brake. With these bare bones, the journey to transform the iconic BMW boxer engine into a category defying chopper began.
It was all a bit of a guessing game, anything can work if you set your mind to it, I trusted in my fabrication craft and my eye for detail, it was just a question if I had the patience or not.’
Engineered To Slide
The forks draw attention straight away, with their sharp angles and clean lines. “This was always in the plan, as I love the triangulation and simplicity,” says Nigel. “I used 19mm diameter Chromoly tube to construct the fork, but the ‘spring’ is made from carbon fiber—using five layers of ‘prepreg’ shaped over a 3D-printed mold, baked in an oven under vacuum. It’s super strong and works incredibly well.”
The wheels have a very distinct design, that takes inspiration from years gone by. The wheel rim was rolled by Stephen from Vintage Rims Australia and Nigel designed the spokes. “The front rim is a 22-inch hoop wearing the same tire that a Model T Ford would have used a hundred years ago,” says Nigel. “It’s a Firestone 28×3, and I bought this tire before making the rim. Tires have a big impact on the stance of a bike, and that’s very important to me. I love the magnesium wheels of the 70s and especially the Motomags that were used for BMX. This is my take on that style, and also harks back to BMWs early ‘snowflake’ wheel design.”
The frame is completely custom, all chromoly, and has removable lower legs to make it easier to remove the engine. “This mounts the engine in position, and ‘hangs’ it in the frame,” Nigel explains nonchalantly, as if it was just another day at work. The standard R nineT transmission and drive shaft have been kept but re-angled it to suit the frame. “It gives the bike a very sturdy driveline, and it absolutely rips!” The tank design stays true to the classic nature of this build, in a peanut style taken from the Lowbrow Customs catalogue, with the tabs removed to give it a seamless ‘floating’ look on the frame. Also from Lowbrow is the rear ‘Manta Ray’ fender, with a little upturn that ties in with the angle of the exhaust and frame.
Its been a wild ride and one that I have had a lot of fun seeing come to life.’
Engineered To Slide
The beautifully crafted titanium exhaust and intakes are simple in design yet highly functional. “It’s a very analogue bike,” Nigel reveals. “The factory ECU and injection is gone, and in its place is a Morris Magneto that’s driven off a pair of dry sump pulleys, which bring a motorsport aspect to this build. I wanted this to emulate a 1960s drag car supercharger, and it fills in the area perfectly.”
To finish off the build Nigel kept the controls simple. Installing a Prism Supply throttle, a rear brake operated by the right heel and a heel operated clutch driven by a rear brake master allowed the handlebars to remain clean and display the distinct lines.
From a dream Born Free Show invite that could never be lived out, to being impacted by the lockdowns that have affected all our lives of late. Nigel never wavered over these challenging couple of years and has delivered one seriously incredible machine.
Sit back and enjoy this masterpiece of motorcycle fabrication.