100 mph on a human-powered bike?
Sure, you've heard of Usain Bolt, the fastest man alive and world record holder in the 100 meter dash. But have you heard of Graeme Obree? He might soon be the fastest man alive on two (self-propelled) wheels.
Nicknamed "The Flying Scotsman," Obree is known for designing bikes that use atypical rider positions. They might be unusual, but his bikes are fast. He has twice broken the world record for the longest distance biked in one hour. And he thinks he can break the human-powered vehicle land speed world record. Not just break, but smash the current record of 83 miles per hour. He believes that he'll reach 100 mph on this bike:
Obree is using a unique push-pull pedal system. He explained the design to Humans Invent:
The frontal arear is minimal since the feet just miss each other on the way past which means the width at the back is the minimum possible so the vehicle can be tailed of short. Also it means the knees are closer together and partially share the same space at the bottom of the stroke which means that the skin can be tucked in closer, and that means less frontal area.
In order to achieve this a direct drive to the rear wheel is replaced by a drive to chainwheel which then connects via another chain to sprocket which turns a bigger chainwheel which in turn connects to the rear wheel. Some of the energy is consumed in this mechanism but the aerodynamic advantage should be much larger than the losage. The push pull arrangement means that the knees do not dip as far as would be the case with a circular movement, again reducing the frontal area and air resistance.
An attempt to break the record in the United States was canceled. Obree is currently looking for a good place to attempt the record in Britain when his bike is finished. He expects to make the attempt later this fall. For now though this video of Obree building his bike will have to suffice.
Photo: Humans Invent