Crackpot Engineering: How to Carry a Bike on a Motorcycle

“Where did you get that?” Uh… my garage.

“Is that safe?” Nope, but neither is loud music, mountain biking, casual sex, heavy drinking or eating fried chicken, but they’re so much fun. If you want safe you should stay at home and play with your Wii.

My objective: to fabricate a device that would allow me to carry a bike on my motorcycle (perhaps to a gravel CX race?). Since my wife is a frequent passenger, the device would have to stay out of the way of her comfort, or be reasonably easy to take off when riding two-up. I went through a few iterations of the design in my typical scattershot, crackpot, hurry-up-who-cares-about-safety-or-quality prototyping process. For the first design I ignored Occam’s Razor and instead went with Occam’s Rube Goldberg machine.

Since my bike (a Suzuki VStrom) is intended for adventure touring there are mounts for side cases and a top box already installed. By removing the top box and measuring the mount points I drew up a design for a plate that could clip into the base. On this plate I would mount the tray and fork clamp from a donated Yakima roof rack. My good friend and master fabricator Dan (Rack n Roll) helped with the machining of the aluminum base plate.

And to achieve my quick release design goals it comes off nice and clean like this:

But man is that thing heavy. Plus it’s far away from the “moment of gyration” i.e. the point where the rear wheel contacts the road. My friend and accomplished mechanical engineer Dave told me the farther away from that point, the more the motorcycle’s movement will be translated into the mounted bike. I got a good deal of side-to-side swaying while riding rough roads, so I went back to my team of science chimps for a newer, simpler design. After digging into my parts supply I decided to use the crossbar from the discarded roof rack like so:

It won’t work on every moto, but the beefy passenger grab rails serve as a perfect mounting point for the crossbar. It’s lashed on with 550 pound test US military paracord, easy to put on and remove when required. As an added benefit I can still use my top box and the left side luggage case for my riding gear (or beer, handguns or raw ether). The last piece to the puzzle is the fork mount.

I pulled off the passenger footpeg and replaced it with a fork clamp bolted onto some cromoly tube stock. Version 3.0 will get a smaller, lighter fork clamp from Delta and I’ll hose clamp it directly to the passenger peg. Simplify, simplify, simplify. And there’s no patent protection for this gizmo so if any of you out there have as little regard for personal safety and weather-protected transportation as I do, have at it. Just don’t say I didn’t warn you… be ready for lots of dumb questions by people who don’t get it. I’m not sure I get it either, but it sure is fun.

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