Watch This Bicycle Go 80 MPH
Probably not do-it-yourself
Tom Donhou, a bicycle builder based in Hackney, London, just went 80 mph on a bike. As a point of reference: You or I might hit 30 mph, tops, on a flat surface; a professional might max out at about 45 mph. But to get anywhere over that speed, you need a bike explicitly designed to go really freaking fast.
And Donhou did this not on some absurdly over-engineered bike; Donhou just consulted a few friends in the business, built the bike, turned his old Ford Zephyr into a pace car/wind screen, and pedaled hard. “This is all new to me. It’s been a total learning curve,” he says.
The Bike In All Its Glory
Here’s how he did it:
Power: Normal bikes typically have chainrings with 20-50 teeth. A larger chainring makes it harder to get going initially, but allows you to reach much higher speeds. The chainring on Donhou’s bike has 104 teeth, and was custom-built to guarantee that the chain stayed aligned at high speeds.
Stability: The frame is built from Columbus MAX tubes: steel ellipses strong enough to significantly minimize the wobbles you get when you’re going really, really fast. Also key for stability is a low center of gravity, so Donhou placed the huge chainring as low as he could on the bike. Lastly, at absurdly high speeds, tires are prone to jumping off their rims. (Yikes.) After consulting some experts, he chose tubular tires, as opposed to clincher tires, to avoid that fate. Tubular tires are glued directly to the rim; clinchers just hook on.
Aerodynamics: The purpose of the pace car is to rule out most aerodynamic concerns; to block the wind for the biker. Donhou added wooden extensions to the car to create a little wind-free haven for him to slip into. Still, two aerodynamic considerations remained pertinent. First, Donhou had to be sure his body was low enough to be completely immersed in the hollow; hence, the custom low-hanging, A-frame handlebars. Next, since the Zephyr isn’t low enough to the ground to block the tires from wind and drag, Donhou had to choose his wheels based on their aerodynamics.
He didn’t beat the bicycle speed record. That was set back in 1995 by Fred Rompelberg at an absurd 167 mph, with a dragster pace car and an elongated, expensive bike instead of the clunky Zephyr and a nearly normal-looking bike. Donhou and the bike can technically reach at least 102 mph, as indoor tests on rollers prove, but the record wasn’t the goal.
Who knows what Donhou will do down the line, though—from the looks of it, he’s hooked on going fast.