Today, most bicycles are fitted with 27.5-inch or 29-inch diameter wheels. The new DirtySixer—the first in a range of big bikes for big riders—uses 36-inch wheels. And the rest of the bike is scaled up, too, creating what its designer, a crazy Frenchman, claims is the first bike truly optimized for tall people.
“What if you were living in a world built by 12 year olds?” asks David Folch, the 6’6” frog behind DirtySixer. “Houses, cars, clothes, all designed and fabricated for a 12-year-old’s height. That’s the world we tall live in.”
“A few years ago, I broke my ankle riding one of those scaffolding frame bikes—regular size wheels, with a taller frame—so I decided to make something better,” he says. “I learned bicycle design, and set out to make a proportionate bike for my body. By scaling up the wheel size, and every single bit of the bike—tubing, bearings, axles, cranks, pedals, bars, saddle, etc—we created the first bicycle that looks good under a 7-foot-tall rider. That makes it safer, more comfortable, and more durable. Plus, those big wheels soak up anything you throw at them: rocks, roots, potholes…even raccoons!”
Making a bike for a tall rider isn’t simply about increasing the seat height. If you compare the DirtySixer to one of those “scaffolding bikes” Folch mentions, you’ll see that, on the DirtySixer, the seat is located more amidships, better balancing the rider in the middle of the bike. “The longer wheelbase moves the weight of the rider forward, to the center of the bike, resolving the inherent instability of regular bikes that were adapted to tall riders," he says. "I also wanted a more comfortable riding position, and increased pedaling power through longer cranks, proportional to the rider’s inseam.”
Folch didn’t arrive at the 36-inch wheel size by accident. Needing an existing source of tires for his bigger wheels, he looked to the unicycle world. “American company Coker, specialists in hot rod and vintage car tires, came up with this size for unicyclists,” he says. “We have a very good tire made by VeeRubber.” Without gears, a unicycle’s top speed is pegged to wheel size. The bigger wheels were developed to make them go faster.
But, on a bicycle, bigger, heavier wheels mean slower acceleration, right? “Our riders average 6’8” and 280 pounds,” says Folch. "The average cyclist is 5’8” and 165 pounds. Acceleration depends on leg strength, and with longer cranks, it’s not that bad. Yeah, it’s a bigger wheel with more material, but think about momentum: these huge wheels carry speed and will just roll over pretty much anything thanks to their lower angle of attack.”
The completed bikes weigh about 30 pounds, depending on the build specs.
In this video, from San Francisco's Exploratorium, Folch walks you through his bike's advantages.
This first generation of DirtySixer bikes is being made by Ventana Bikes in Sacramento California. Folch describes it as an “All-Road” design, capable of commuting, touring, and tackling mountain bike trails. He and his other (tall) test riders have been racing the bike for the last three years in Northern California’s Sea Otter Classic cross-country race,have ridden it day-to-day around San Francisco, tackled local trails, and even passed prototypes around for feedback from the famously tall. Shaquille O’Neal has taken one for a spin. His reaction? “Wow!"
DirtySixers will come in four frame sizes for riders ranging from 5’11” all the way up to 7’4”. Need something bigger? Folch says he’ll make you something custom. He put the project on Kickstarter three days ago, and has already sold five examples, exceeding his funding goal. The cheapest DirtySixer, a single-speed, starts at $3,500.
Once that order is filled, Folch plans to bring to market a dedicated mountain bike, complete with scaled-up front suspension. “Being tall should not prevent you from riding an awesome bike,” he says.