12-11-2014 03:00 PM
When bad things happen to good builders

BY RADICAL BRAD, ATOMICZOMBIE.COM

Wheel dropouts broke off of an electric hub motor, causing a dramatic crash.


"Perhaps this one was only partly Murphy's Law fault, leaving the other half of the blame to the crazy dude that didn't listen to reason. When I was building the E-Style Electric BMX, I originally put on a pair of front suspension forks from a mountain bike. Now, this might not seem like a bad idea, but if you know a little about electric front hub motors, then you probably know that this is a recipe for a face plant.

Here is the problem in brief. Front suspension forks have aluminum dropouts. Aluminum is an evil unpredictable metal. Front hub motors introduce heavy torque to the axle. The axle is connected to the dropouts. Eventually, the aluminum dropouts rip away from the fork tubes and you get a very rude and swift introduction to the pavement. Sadly, I knew this ahead of time.

I never intended to release the plan with these forks, but didn't actually think that such a well-made set of forks would be an issue, so I threw them on for some test riding one weekend. My hub motor was only rated at 500 watts, but I did modify the controller and bump up the voltage from 36 volts to 48 volts, boosting the top speed from about 25 Mph to 40 Mph or better!

There I was smoking down a street in my neighborhood and I took a sharp turn into the parking lot of the coffee shop I like to visit, trying to look cool as I carved into the lot running under silent electric power. Actually, I did look cool until the exact instant that the front wheel went in a different direction than the rest of the bike!"

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