Cheat Like the Pros: How to Hide a Motor in Your Road Bike

The Vivax-Assist motor and battery fit in your bike frame and provide 200 watts for 60 minutes.
The Vivax-Assist motor and battery fit in your bike frame and provide 200 watts for 60 minutes. 

At the recent Cyclocross World Championships, Belgian rider Femke Van den Driessche was caught with a small, lightweight electric motor in one of her race bikes. Though rumors have circulated since 2010 about the potential for mechanically assisted bikes in pro racing, this weekend marked the first time cycling authorities had actually found evidence of cheating.

The market for e-bikes — bikes with electric motors that help you pedal — is growing so quickly that Claus Fleischer, who heads up Bosch's e-bike systems, predicted recently that a third of bicycles sold in Europe would be e-bikes by 2023. Electric-assist bikes, though, are largely the ride of commuters, not competitive cyclists. 

Typically, electric bikes include a motor in the rear hub and a large battery pack attached to the downtube. On pedal-assist bikes such as the Specialized Turbo ($3,000), the motor only engages when the rider pedals. And some e-bikes, such as the Raleigh Detour iE ($2,700), place the motor in the bottom bracket. Neither bike hides the fact that it has a motor, and they'd offer no competitive advantage in a race due to their weight, limited range, and max speed of 20 mph. 

Kits offered by E-BikeKit are also available to turn your existing bike into an e-bike. The kit includes a battery, throttle control, and hub system. A 20 mph engine with a 12–26 mile range will run you $1,361. Of course, this is a less elegant solution than a bike designed with an integrated motor system, but it offers an affordable way to electrify your commute.

Not surprisingly, the technology used on Van den Driessche's bike was a bit different than what you'd find on a commuter-style e-bike. When cycling authorities removed the saddle from her bike, they found a bundle of cables in the seat tube. The cables connected to a miniature engine built into the bottom bracket of the bike. There were no visible signs that the bike included a motor, and the authorities only discovered the technology with a specially designed scanner.

A similarly low-profile motor is available to consumers, the Vivax-Assist ($2,930). First released in 2008 as the Gruber-Assist motor, the Vivax-Assist inserts a motor into the bottom-bracket assembly. A small battery pack slides into the seat-tube, out of sight. The motor is activated by a power switch on the handlebar. The Vivax-Assist can boost your power by 200 watts, which is about half the output of a Tour de France rider climbing a mountain. The battery can sustain the assist for 60 minutes and has an advertised weight of 3.9 pounds.

"The Vivax feels very different," says Peter Stuart, a staff writer at Cyclist magazine in the U.K. Stuart did extensive testing with the Vivax system and found it to be tricky to learn how to get the most out of it. Picking the right gearing is essential, and you have to set your cadence (how fast you're pedaling) to the motor's output. "If you're in too low a gear, you'll quickly spin out and the motor stops assisting," Stuart said. "Essentially, it takes a lot of practice to maximize the gains from the motor."

Once you master the intricacies of the Vivax-Assist, it's a pretty amazing feeling. "It's like you've got a tailwind and someone pushing you from behind," says Stuart, who hit a personal record on one of London's big climbs. And though Vivax doesn't openly encourage cheating, it does offer a $540 upgrade called the "Invisible Performance Package."

Actually using a motorized bike in competition would be a more difficult proposition, says Stuart, due to the necessity of dialing in gearing and pedaling speed. And of course, there's the small matter of the UCI rules. A rider caught cheating with an electric motor faces a minimum of six months suspension and fines ranging from around $20,000 to $200,000.

But electric motors are just the beginning for mechanical doping, according to a report in the Italian sports newspaper Gazzetta dello Sport. The cutting edge of e-assist motors is wheels with embedded magnets that increase their rolling speed. The electromagnetic wheels reportedly add anywhere from 40 to 60 watts of extra power. The technology is not available to consumers, and no one has reported seeing the wheels in use. 

There's no shame in buying an e-bike to ease your commute, but know that installing an unseen performance package on your road bike won't garner you any friends. Besides, the easiest way to get faster — without breaking any rules — is to ride more, and that's why you bought your bike in the first place.