A unique BMX frame tests the limits of an electric bike’s capabilities. Sam Barker and Tom Stanton, two friends who enjoy tackling weekend projects, transformed a standard BMX frame into a speed machine. What they created is a beast that feels more like a dragster than a pedal assist bike, a tiny BMX frame with enough power to raise the front wheel and outperform more standard e-bikes.
The project began by simply plugging a 20-inch BMX wheel equipped with a 3kW hub motor into an existing bike in the garage, powered by a 72 volt, 20 amp-hour battery. Initially, some quick spins around the block revealed some potential acceleration, but pushing the throttle wide was all it took to send the back wheel spinning into the air and the front end flying off completely due to the narrow wheelbase.
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They knew they needed to solve the handling issues, so they brought out the welder and cut the frame, adding a meter of 12mm mild steel tubing to give it some significant stability. They added some reinforced brackets to make the whole thing feel sturdy, almost like scaffolding. The longer frame kept the front wheel on the ground during those violent launches, and it also allowed them to finally tuck the battery inside the bike. They also changed the handlebars to a unique design to give them better control, and they adjusted the pedals to make them exactly perfect.
Stopping was accomplished with a borrowed rim brake caliper from a penny-farthing cycle. To be honest, it sort of works, but don’t expect to be able to stop on a dime soon. The machine overheats a lot under severe braking, and it won’t slow you down enough to be safe at the speeds it can reach. They did identify a workaround by shunting the motor wires to enable regenerative braking, but the main brakes remain marginal.
When they eventually took it out for a ride, they discovered the bike’s personality: it creates so much acceleration that the back wheel starts spinning before the rubber really has a chance to grip, and then you’re past 50 or 60 kph, feeling the speed wobble from the sharp steering angle. It’s not particularly stable, but it’s far superior to the original short version. While there is no fairing to protect you, and the low seat causes you to bounce around on the pegs, you must agree it’s a lot of fun.
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