Racer X Testing The Limits Of Electric Motorcycle Design

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Electric motorcycles tend to look strangely conventional. Even the oddball $60,000 Curtiss Zeus has a ‘tank’ and a seat where you’d expect them to be.
So although the powertrains are revolutionary, the designs tend to be evolutionary. And we’ve often wondered why. Perhaps motorcyclists are just too conservative?

Mark Atkinson, the bike builder and machinist who built the incredible BMW ‘Alpha’ Landspeeder, has pondered this question too. And he’s just created this extreme e-bike to find out where the limits of design are.
It’s not practical and it’s no good as a commuter bike, but it’s one of the wildest two-wheeled vehicles we’ve laid eyes on.

So what happened here, Mark?
“A couple of years ago I met one of the engineers from a now defunct e-bike company at a show. He said that even though they made great bikes, they weren’t selling well. He asked what I thought.”

“I told him that electric bikes were an opportunity to do something spectacular. Gas tanks on electric bikes seem silly to me.”
Mark decided to see how far he could push the envelope. “What would I build if I had no preconceived idea of how a motorcycle is supposed to look?” It would be clean slate design: two wheels and electric power.

Simplicity was Mark’s starting point: He wanted to make the suspension and steering pivot from the same axis. “I drew an X on a napkin… The pivot point didn’t work in the center, so it got moved as far forward as possible.”
“The steering took some thought. My friend Tom Burkland said that if I used two pivots per attachment point, it would work. I did, and it did.”

While pondering over all this, Mark got emailing with Kim Lohstroh Young of The Vintagent. She was organizing an electric bike show at the Peterson Automotive Museum, loved Mark’s concept, and gave him three months to finish it.
“Kim asked me what the name of the bike was,” he says. “I have never named a bike, so I told her I didn’t know. She said it was called ‘Racer-X.’ Cool.”

After experimenting with a carbon fiber monocoque backbone, Mark decided to use an aluminum tube structure for the bodywork and cover it with carbon panels. Challenging, but doable.
Once he got the mock up together, he found that the steering actually worked as modeled. He made a steering box, controlled by a servomotor hooked up to Arduino open source software.

“This pivots the front two arms of the X that actuate the front wheel. The steering box is then mounted to two linear bearings on the rear solid section, and a shock allows the whole bike to be suspended without effecting the steering.”
There’s a tiny joystick control mounted in the left side handgrip. “It works okay but I will modify the program to be a little more progressive.”

Because of how the steering works, Mark had to exaggerate the movement of the front wheel. So the steering axis had to be offset from the center line of the wheel.
That’s when Mark came up with the hub-less wheel design. Each wheel’s center unit was machined out of a big chunk of aluminum. Two carbon fiber rim sections that hold the tire were then bolted to the main unit.

The entire wheel assembly sits on a custom-built carrier at each end, and rides on mounted bearings. The chain runs through a cavity in the wheel’s center, with a sprocket that runs on a shaft through the main bearing plate. And there’s a special disc brake setup up front.
It’s a lot of higher grade engineering that we still can’t quite wrap our heads around. But that’s not the end of it; there’s a really cool story behind the motor, too.

“I have raced with the Perdue University team on the salt flats before,” Mark tells us. “They run an electric bike that hold several records in the 115 mph range.”
“I emailed Dr John Sullivan—who rides and heads up the team—what I needed for power, as I am new to the electric bike world. He had just upgraded their bike’s drivetrain and offered me the old setup. Race history established!”
A Sevcon controller and Nissan LEAF batteries supply power to the 38 Kw motor.

Racer-X is arresting, complicated and completely over the top…and that’s good. As the electric vehicle market grows, we need builders that are willing to take the leaps that manufacturers can’t.
“My hope in building this,” says Mark, “is that it sparks some new ideas in the electric bike world. We are at the cusp of a new era in motorcycling.”
Would you agree?
Speed of Cheese Racing | Instagram | Images by Kaycee Landsaw



from Bike EXIF http://bit.ly/2WYFJwO

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