First Ride: Bimotal Evation eBike Drive System


eBike Drive System

Toby Ricco had a lifelong dream of being an engineer at Tesla. His obsession with the company started at a young age. Finally, after finishing college at UC Berkeley, he realized his dream and became a mechanical engineer for Tesla, working on things like the power train for the Model 3. He spent five years doing the kind of work that has helped make Tesla such a valuable company in both the tech and automotive world.

Toby Ricco and one of his Bimotal Evation drive-unit prototypes.



Toby loves mountain biking and skiing, two things he has done often in his free time. However, one particular day of skiing in Squaw Valley would throw a serious wrench in the works. While going over some moguls, he crossed his skis and crashed, seriously damaging his knee. Even after he’d recovered, his knee still gave him problems when riding his mountain bike. 

He had a bike he loved, a non-assist Cannondale Lefty that he’d spec’d out just the way he liked it, only now he wanted some electric assistance. This was back in 2016 before there was such an expansive market of electric mountain bikes. At the time, he also didn’t want to spend $5000–10,000 for a really heavy bike. 

When mounted, the unit sits atop the brake caliper and kind of resembles a really big caliper version.


After investigating all the bolt-on conversion options out there, he thought there must be a better and, more important, a lighter way. Perhaps some kind of a modular unit that could quickly be added to a non-assist bike, so that instead of having two bikes, you could have just one that could be either electric or non-assist. 

Being a mechanical engineer, it didn’t take long before he came up with a good idea. However, pursuing the idea would require him to quit his dream job and go for it 100 percent. He came up with a concept to attach a powerful but lightweight electric motor to the rear wheel in a pretty unique way. 


The system is made up of a motor that goes on a mount that sits atop the rear brake-caliper mounting bolts, clipping into a receiver mounted there with what looks like a pair of quick-release seatpost clamp levers. The outbound pinion gear meshes with a gear bolted to the inside of a new brake rotor to drive the wheel on demand via a throttle mounted on the handlebars. 

Once the system is installed, attaching the drive unit takes literally a few seconds.

The gears that mesh are made of two different materials—one is metal and the other is a polymer compound. This is to make it quieter, wear longer and if some grit does get in between, the polymer can absorb some of it. There will be a semi-cover on the production model.

One of the prototypes had the first battery they built, which, despite being big and boxy, could use the right number of 18650-sized lithium-ion cells to get the right power and range. Currently, Bimotal has a prototype battery that is round and designed to fit in a water-bottle cage.

Some of this hardware is designed to stay on the bike permanently, with the battery and motor system being attached when a rider wants the bike to be an e-bike. The plan is to have the system delivered and installed by the roving concierge bike mechanics from Velofix so that customers won’t have to do the installation.

These are the gears that mesh between the motor and the wheel.



Bimotal invited us to the nearby San Gabriel mountains for a test ride on the prototype. While the drive unit looked very close to a finished product, the batteries on each of the two bikes were different and didn’t look like production units. 

We took it up some steep inclines, loose dirt, gravel and more, and it performed as well as many mid-drive bikes we’ve ridden.”

The motor puts out a really quiet 50 N/m of torque that Ricco says he’s trying to get up to nearly 100 N/m. That would be impressive. The Evation is about the size of a smartphone, but two to three times as thick. We rode the bike up some steep inclines with plenty of loose dirt, and it performed as well as any full-production, mid-drive bike we’d ridden. It’s obviously heavier than a traditional full-suspension mountain bike, but not by as much as a traditional e-bike motor/system, so it’s actually very nimble.

This is a prototype battery that is not the final form, but rather a test mule that has the right number of cells and power. The final form factor will be more like a water bottle.


Getting that much power out of such a small motor is remarkable, but it’s thanks to the talent Ricco has plucked from his working days at SpaceX and Tesla. For example, the engineer designing the magnets for the motor also designed the magnets for the motor on the Tesla Model 3. Truly, he has a team of rocket scientists working on this.

This one is shaped like a water bottle on purpose so it can be quickly installed/released.


The system will sell for an expected $2000, which will include installation and a full bike tune-up from Velofix. That’s a fair amount of dough, but if the company can scale the way some of the big tech companies do, the price could drop in time. Still, it’s cheaper and less space-demanding than owning a traditional bike and an e-bike, which could be ideal for people who don’t have the space for multiple bikes. Keep in mind, too, that this isn’t just for mountain bikes, as the whole system can adapt to any bike that uses disc brakes. 

We did an interview with Toby about the company where we delve deep into the project. If you’d like to hear it, check it out on our podcast on Apple Podcasts, Spotify, Stitcher or wherever you like to listen to podcasts.

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