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.
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.
Drafting behind a car is kind of cheating. Sure I could go faster on a bike if there were no atmosphere at all, and I could go even faster on a frictionless surface, or if there were no gravity, etc. This is an interesting exercise, but if it is to be applied to the real world, a fast bike needs to be able to deal with air resistance and gusts of wind.
Oh no! A 0.01% grade! Time to walk...
Without wind resistance are you really going 80MPH under your own power? Seems to me this isn't much different than being pulled by the car.
I always thought a draft was almost like suction or at least like an area of low pressure behind the back of the leading vehicle/object. The turbulence creates mini horizontal tornadoes/vortexes (don't know the technical term) that spin counterclockwise which basically sucks the trailing object down the road.
The record breaking lead vehicle looks like it was made to exploit that principle to a extreme with the wedge shaped tail (not terribly aerodynamic but my guess that was not the goal, which I assume was to create turbulence) whereas the Donhou leading vehicle's tail is much more aerodynamic and the bike is merely in the slip stream and does not gain as much from the "beneficial" turbulence.
I bet he could gain a few more MPH with a redesigned tail on the leading vehicle.
Lets see what Wiki/guiness says:
Fastest flat surfaced unpaced = 83mph (him alone on the bike! Cowling yes but none the less)
Fastest flat surfaced motor paced = 167mph
So.... Lets just say that i'm not overly impressed with this "record"
But all the power to him!
i am sure that the head will survive. not sure about the extremities however, they just might become a cliché: "be one with the bike"
Add a Nuvinci to that bike and he can improve his takeoff speed.
@HBillyRufus: For the record, frictionless surfaces tend not to play well with vehicles that are powered by drive wheels (The wheel that's supposed to drive the vehicle forward just spins freely).
Generally, I agree that this seems like a somewhat silly article since he only managed to go half as fast as the current pace car record, but props for the DIY approach.
Nisi credideritis, non intelligetis.
technically you won't even move an inch on a frictionless surface.
In motor-pacing, the pedals are for control more than primary power, which is provided by air pressure. As for DIY - The guy who took the record to 120 MPH was so broke, he had a note in his pocket asking to be buried where he fell, if he did.