California cyclist Denise Mueller set a women’s world speed record of 147mph Saturday, drafting an SUV on a wildly unique, fixed-gear bicycle on the Bonneville Salt Flats of Utah in the United States.
The 147mph marked a new Woman’s Paced Bicycle Land Speed Record, a style of extreme speed that dates back to 1899 when Charles “Mile-a-Minute” Murphy drafted a train on a bike, with sheets of plywood laid down between the rails the tracks for a riding surface. Murphy completed a mile in 57.8 seconds, according to newspapers at the time.
For Mueller’s record — which she is trying to improve today and tomorrow — the 43-year-old mother of three drafted pro auto racer Shea Holbrook, who piloted a Range Rover with a specialized rear fairing. She is being coached by John Howard, a three-time Olympian who set a land speed record of 152.2mph in 1985, also while drafting a dragster on the Bonneville Salt Flats.
Chris Garcia of SD Wheel Works built the bike with help from DaVinci Bikes and KHS Bicycles. The construction centers around power production and stability at a speed well above anything normal bicycles can achieve. Not one but two 60t chainrings are used for double-reduction gearing; one full revolution of the pedals equals 125 feet.
The bike is a fixed gear; there is no coasting or shifting for Mueller, who must be towed up to speed with the gigantic gear. “We are trying to get up to speed as fast as possible in the first mile before I drop the tow,” Mueller told BikeRadar. “Then we have until mile three to get up to ultimate speed. Between mile markers three and four is where I am being timed.”
When Mueller is going 140mph, her cadence is 100rpm.
The custom 17-inch dragster wheels have shaved tires and sit splayed far apart on the ultra-long frame. A steering stabilizer is used on the massive suspension fork, and a BodyFloat isolation seatpost takes the edge off at the rear.
BodyFloat co-inventor Charlie Heggem said his seatpost is unique in that is undamped. While most suspension seatposts have an elastomer or some other form of damping, BodyFloat uses the rider as the damper, and offers vertical travel of up to 1.5in.
“This terrain out here is anything but flat, and at 150mph it is extreme high frequency,” Heggem said of the Salt Flats. “The BodyFloat springs are able to return energy as quickly as it comes up. An elastomer-based system would become an amplifier as it can’t keep up.”
Howard said he expects Mueller to beat her 152mph mark today or tomorrow, and perhaps even eclipse his old record of 152.2mph. The men’s record of 167mph isn’t attainable, given the location, Howard said.
“We don’t have enough track to beat the men’s world record,” Howard said. “We’ve got four miles and we’d need six.”
Mueller said getting up to top speed isn’t a linear progression. “I call it the dance,” Mueller said. “It is not a steady increase. It is a surge and then relax, surge and then relax. Shea also has to do that with the pace vehicle.”
The bike has a front bumper built into the frame, which can push up against a complementary piece on the vehicle. Mueller has two strange brakes on her bike — a hydraulic caliper on one of the two 60t chainrings (which slows the rear wheel because it is a fixed gear) and a caliper on the rear rim.
Mueller says she tries not to use the brakes when feathering her speed behind Holbrook. The two women have microphone communication, and the vehicle’s rear camera is permanently on, with Howard sitting in the passenger seat.
Regardless of whether she tops her record, there remains the business of slowing down on a fixed gear at 140+mph. Holbrook will stay in front of Mueller until they drop below 100mph, then will accelerate away to let wind resistance slow Mueller down.
BikeRadar will update this story if and when Mueller improves her record.