We all have our favorite bike, and giving up that love affair to get an e-bike is no small decision. And no small cost. But Bimotal lets you add a little electric assist to any bike, then quickly remove it when it’s not needed.

Not only does it require virtually no modification to your bike, but it doesn’t add much weight, either. Here’s what you need to know about this universal e-bike upgrade…

Bimotal add-on e-bike motor specs

prototype bimotal elevate external add-on ebike motor
A prototype of the Bimotal Elevate.

The Bimotal Elevate uses its own toothed brake rotor to engage with a small, self-contained motor unit driving it. It’s powered by a water-bottle-sized battery, and for starters, it’s activated by a throttle. Stay with me.

The goal is to add assist to your pedaling, though as is, you could use it to just cruise without pedaling. Founder Toby Ricco says he mainly uses it to shuttle, and is well aware of the legal limitations a throttle-only setup provides for mountain bikes and some cities.

So, he’s working on the pedal-assist capability and expects to have it working before the first units ship in early 2021. The Bimotal Elevate has Bluetooth, letting it communicate with an app, so it could be as simple as linking it to a Bluetooth (or possibly ANT+) cadence sensor.

Great, but who’s Toby?

bimotal founder toby

Toby came from Tesla, where he worked on power electronics for the Model 3, Model S and Model X while tinkering on the design for Bimotal.

Joining him are Lauren Deunsing, VP of operations, was with NICA for years and brings bike industry experience, and Jason Roesslein, director of product, who also comes from Tesla and SpaceX and has a long background in cycling.

Bimotal specs & weight

cad drawing showing how Bimotal Elevate e bike motor connects with the gear on the disc brake rotor

The motor is able to deliver a constant 50Nm of torque, with a max of 100Nm. And it’s turning that into forward motion with a 30:1 gear ratio via hidden reductions inside its shell. That’ll get you up to 28mph on flat sections, which is equivalent to a Class 3 e-bike.

By the time it ships, it’ll have the ability to select the tune you want or need based on the situation. Many eMTB-friendly trails still limit bikes to Class 1, which has a 20mph cap on its assist. So, you’d be able to pull up the app, set it to Class 1, then hit the dirt.

Toby says it’ll probably have multiple modes and options, so you can customize the performance to your needs.

prototype bimotal elevate external add-on ebike motor

The 750W motor unit is about 1kg, which is a fifth or less of the weight of most hub-based motors. That means there’s not a ton more unsprung weight being added, but definitely some. Fortunately, you can pop it on to get up the mountain, then pop it off for the descents…all in about 10 seconds.

The 250Wh battery is 1.5kg, and hardware and harness and stuff is about 200g. All in, it adds about 2.7kg (5.9lb) to your bike. The brake rotor is 175g, so not too much heavier than a standard 180mm 6-bolt rotor. They could add a CenterLock rotor in the future.

Range is estimated between 15 to 30 miles, depending on use.

What does it do to the brakes?

digram showing parts added to the bike for the Bimotal Elevate e-bike motor system

One concern is heat, as you certainly don’t want motor heat affecting rear brake performance. They say the heat is almost immeasurable, as the motor is physically separate from the rotor, and it’s several gears away from the ones that finally connect with the rotor.

The current design has no drag, as the motor just spins freely when not activated. But, they’re working on a way to switch on regenerative power, letting you charge the battery on the descents.

Will it work with my bike?

Well, it’s important to know that it’s not actually available yet. They’re still working out a few details, but the basic concept is set.

The most important requirement is that you need to have an externally (seatstay) mounted rear brake caliper. It works with most any brand and style of hydraulic brake. To install, you simply remove the standard M6 bolts and swap them for their bolts with extended studs. The motor unit slides onto and clamps into those.

During installation, it’s tuned to match its output with your wheel size so that it meets Class 1 or 3 speed limitations. Its position is set by adjusting the height of the bolt studs, and they want the pros doing that for you. Which is why, if you want it, you’ll get it through Velofix, who’s trained to do this correctly.

Yes, there are some very obvious ways you could “hack” it to go faster. Look for OTA firmware updates through the app to keep it humming along with new options as they grow. Retail is planned at $1,950, available in early 2021. Preorders are open now.

Bimotal.com

32 COMMENTS

  1. Interested and will be watching progress. By the way, most road disc brakes are either 140 or 160, so a minimum of 180 will be a deal breaker.

  2. Looks pretty cool. It would be great if they could make a version to fit on the chain stay, since that’s where most road bike brakes are. Maybe flat mount, with a slightly different shape and mount pattern.

  3. I’d throw this on my hardtail and commute in a heartbeat. Absolutely. Not something for trails, but I’d love to give the finger to the gas station as I ride by…

  4. I don’t think something like this is a worthwhile proposition until regenerative braking is added, at $2k on top of the bike cost you may as well buy a ‘real’ ebike and be done with it.

    While there is plenty of strength in the brake mounts to handle any load the motor could dish out, I would be concerned about the sideways leverage on the mounts in the case of a crash. That motor is sitting a long way above the brake caliper, and sitting well outboard of the chain stay it would almost inevitably hit the ground in any crash onto the non-drive side.

    Setting it up on the front wheel could add real benefit on low-traction technical climbs (yes, I’m aware the fork/rotor/spoke clearances are smaller and a design change would likely be required to accommodate).

  5. It’s things like this that keep me in the “no e-bikes on the trails” camp..
    “So, you’d be able to pull up the app, set it to Class 1, then hit the dirt” – or not. Who would actually do that? Nobody. So now you’ve got Class 3 ebikes on trails.

    No. Just no.

  6. That’s a lot of promises… Under promise. over deliver has always been my motto…
    I’ve gone to the darkside boys! Racing tomorrow at Glen Helen, WORCS, World Offroad Championship Series. Two rides total on an EMTB and i’m in!! Too bad this thing only goes 19mph. My heartrate will still be pegged cause above 19mph it’s all you.

  7. Need to correct some basic errors here. Throttle assist is Class 2…with a speed cap of 20mph. Class 3 is pedal-assist with a speed cap of 28mph. What is described here is legally a motorcycle. Throttle assist in excess of 20mph. Can’t wait to see more people get in waaaay over their head after the battery runs out…or they break the bike its installed on.

  8. This is the best conversion system idea I’ve seen to date. Rechargeable on descents…brilliant. So many options possible like ease of swapping it out. Different mounting options, different battery configurations. Hopefully you can protect it with patents to avoid the raft of copycats that will come. Or just sell the tech to Shimano etc. Good luck!

  9. $2,000. WTF. really WTF.

    I say this as someone that would slap one on their commuter-tourer to get a tailwind effect, as it really all I want after owning a full-fledged mid-drive. Like the evolution of the early quick install friction drives.

  10. With exactly the same 1900 usd I actually built a super ebike with top components and 120 miles range, 1500 watts, Magura estop brakes, Rockshox, 52v battery. This price is a deal braker

  11. What’s ironic is that engineers from Tesla, a company known for design blank-sheet BEV’s, is doing an e-bike bolt-on kit… Kind of like a sad Toyota Camry hybrid; A really decent car in its original design, but heavier and worse after the change.

    • $600 for the kit is practically a miracle (will be better when it has pedal assist). This is less than the cost of a decent suspension fork or a mid level wheelset.

      I’d get a pedal assist version of this for my commuter bike right away.

  12. We’re glad you’ll be along for the ride, Joe!

    To make sure it’s clear, you don’t need to have 180mm rotors currently, just be able to fit them, so if you are externally (seat stay) mounted (typically ISO/post mount, see bimotal.com/compatibility for diagram) we’ll be able to mount up (using an adapter if needed to clear our 180mm rotor, with attached gear).

    That said, we understand many bikes (road/gravel/xc/etc) brakes are internal (chain stay) mount, and, as Toby’s mentioned, we’ll be working on that solution once we have the bandwidth – stay tuned!

  13. Hey Manny, we’ll be working on price as we progress, as well as offering lower priced variants down the road, but the initial price will give cyclists an alternative for high performance ebike capability by adding it to the bikes they already own, as opposed to having to shell out much more than that for yet another specific bike.

    Paired with your preferred high-end bike, the Elevate system will be lighter than most ebikes, especially considering the power it offers, with the added benefits of direct drive, meaning no added wear-and-tear to chains and cassettes, and being super easy to remove – swap it to another bike, and/or use yours with pure pedal power like you used to.

  14. We’re excited about regen too, Dylan! The one-way bearing we currently use is nice because there is zero drag when coasting, but we’ll be working on the electronic equivalent for regenerative braking once we get our footing.

    Paired with the high end bike of your choice, which many people already have, this offers an alternative to light, powerful, ebike capabilities, without having to shell out much more than the cost of an Elevate for yet another specific bike. With the direct drive, there’s no added wear-and-tear on the chain or cassette, and being removable, you get to keep the same bike you’re used to, and can use it on multiple bikes.

    We get the crash question on occasion, and while we hope you’re not crashing too much, we’ve designed the mounting studs (~$5) to give way before any damage can be done to the motor or mount points.

    • Thanks for replying. As a rule, people who buy bolt-on kits are those who want to save money, not those who have high-end bikes, so I still think your price point is out of whack unless you have regen braking from the start. Otherwise you don’t really have any killer performance feature to offset the negatives (price, fragility, effect on unsprung mass, looking like a dork).
      Even with ‘breakaway’ mounts, I’m not going to be mounting something like this way up high on my carbon seatstay – if those mounts do break away as intended, then that expensive motor is going straight into the spokes of my expensive carbon wheel…

  15. Hack devices are widely available to un-govern all of the popular e-bike power systems. Have you seen anyone shredding singletrack @ 30mph on an e-mtb? I haven’t and I bet it’s pretty rare.

    As ever, the only difference e-assist makes in the mtb experience is climbing. The same limitations that keep speeds reasonable on a conventional mtb (trees, space, traction) apply to e-mtb’s too.

  16. Please stop with the claim of “zero drag when coasting”. The gear on the rotor is engaging (and over-drive ratio) the gear on the motor, so there definitely is drag, even if you, the people who want to make money, don’t think it’s significant.

    I have concerns that applying forced to the brake mount in the OPPOSITE direction that it’s designed to handle them, is a bad idea.

    I’d be surprised if this gets to production. Too many obstacles to overcome.

  17. That doesn’t happen on MTB trails. Motor or not, they’re beholden to the same speed limiters (space, traction, trees, etc.) that the rest of us are. So we’ll get passed on a climb, not a big deal.

  18. This is Class 3 on Trails, and thinly veiled with no regulation. This will help RUIN Mtb trails. I am an avid EBiker as well, but this type of “innovation” is a mockery to our under-funded trail systems

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