After years of rumours, the Rivian eBike is finally here, marking the adventure EV brand’s first big leap beyond cars and trucks and into the broader world of electric mobility.

Through a spin-off company called ALSO, this Silicon Valley startup is planning to disrupt the eBike market by leveraging Rivian’s existing technology, retail network, and economies of scale.

The first products are the ALSO TM-B eBike, along with a last-mile delivery quad called the TM-Q.

My plan with this article is to focus primarily on the drivetrain, because there are a lot of misconceptions about how it works and why Rivian designed it this way. You should get quite a lot out of this breakdown, as I’ve been fortunate enough to spend time testing almost every bike available with similar drivetrain tech.

Let’s now analyse the drivetrain and figure out what makes this system so different from everything else on the market.

What’s Special About the Rivian eBike Drivetrain?

I dug through Rivian’s patent to really understand how this works. It turns out the drivetrain combines elements from systems I’ve analysed on this channel before, notably Digital Drive bikes and eCVT drivetrains.

Up front, you’ll find the crankset, motor, gearbox, and battery all packed together, and they send power to the rear wheel via a belt. These key components are housed inside a cast-magnesium unit that actually forms a structural part of the bike’s frame.

What makes this setup really different is that the pedals aren’t physically connected to the drivetrain like on a normal e-bike. So, when you pedal, you’re actually turning a generator. That generator then sends your power to the motor and battery, while digitally recreating the feeling of a chain with really impressive accuracy.

Bikes that use a pedal generator, such as the Mando Footloose, have been around for about 15 years.

Now, if a “digital chain” sounds like new tech, it’s actually not. Bikes using this kind of series-hybrid or digital drive system first appeared as prototypes back in the 1970s, and consumers have been able to purchase versions of this tech for about 15 years.

The big difference is that bikes previous to the TM-B ditched the chain or belt entirely and sent their pedal power straight from the generator to a rear-wheel motor. I’ll be explaining why Rivian didn’t go down that route a little later in the article.

You might be wondering what happens when the battery runs out. Well, there’s an “infinite turtle mode” that uses the power generated from your pedalling to keep the bike moving. It’s not fast, but it’ll get you home when the battery’s dead.

So, what are the advantages of the Rivian eBike drivetrain?

Advantages of the Rivian eBike Drivetrain

First off, there are no derailleurs, no complex gearboxes, and not even a chain in sight. The ALSO drivetrain has nothing to knock out of alignment, almost no moving parts exposed to the elements, and barely anything you need to clean. It’s basically built from the ground up to be durable and low-maintenance.

A major drawcard is the automatic shifting with unlimited effective gear ratios. There’s no clunk-clunk you might associate with gear changes; rather, the bike moves forward smoothly and quietly. You just pick your preferred cadence (or pedal speed), and the system will change the speed of the bike based on how hard you’re pushing. That will result in a much better user experience for less experienced riders.

If you prefer full control, the TM-B offers manual digital gears. You can instantly change gears anytime under full pedal load, maintaining whatever cadence feels best at the time.

The drivetrain also recovers up to 90% of your braking energy through regenerative braking. Because the belt is always engaged, it can feed power back into the battery while slowing down, extending range and drastically reducing brake wear.

And since Rivian (ALSO) owns the full hardware and software stack, the bike uses your phone as a key to lock and unlock the drivetrain. This means the bike is practically useless if stolen, as many drive components can be remotely bricked by the owner. The rear wheel is locked by the motor, the pedals are decoupled, the battery is no longer removable, and of course, there is an alarm, and you can easily find it with GPS tracking.

Why Didn’t Rivian Get Rid of the Belt?

You might be wondering why the Rivian eBike even bothers sending power to the rear wheel through a belt, instead of just putting the motor back there.

Well, one big reason is torque. The TM-B multiplies the motor’s torque through a combination of internal gearing and the belt reduction. That allows the motor to spin fast and cool, while the wheel gets massive torque at low speeds. As a result, you get faster launches and steeper hill-climbing ability.

With a rear-hub motor, you simply can’t take advantage of the same kind of gear reduction. The motor has to handle everything directly, which means it can’t always operate in its most efficient RPM range, especially when you’re switching between steep climbs and flat sections.

Rivian could have paired a rear hub motor with their pedal generator similar to this CIXI drivetrain.

I’ve actually simulated a comparison between the TM-B motor and a heavy, six-kilogram direct drive hub motor***. The difference is huge: the TM-B can climb gradients up to 30%, versus around 20% for a big rear hub setup. In practice, Rivian’s bike could tackle a 15 to 20% gradient continuously without overheating, while the heavy hub motor would be limited to 7 to 10%.

There’s a handling advantage too. Because the motor sits in the middle of the bike rather than at the rear wheel, weight is centralised and sprung by the suspension. That gives the rear wheel quicker suspension response and much better traction.

So, in short, the belt drive gives you better climbing and accelerating performance, better handling, better suspension performance and better traction.

Let’s now take a look at the disadvantages.

*** I chose a big direct-drive hub motor for this simulation because, when I tested a geared hub with regen in the Grin simulator, the thermal performance on long, steep climbs resulted in overheating. Remember, in this scenario, there’s no rider directly contributing power, so the motors tend to overheat much faster.

Disadvantages of the Rivian eBike Drivetrain

The Rivian powertrain is entirely designed and manufactured by ALSO bikes.

The biggest drawback is that the Rivian eBike is almost entirely proprietary.

The vertical integration is what allows it to deliver such impressive performance and features, but it also means you’re depending on ALSO to not only keep producing proprietary components but to keep their service network alive.

For ALSO to really succeed, they’ll need a service network that’s accessible to their customers, and they’ll need replacement parts in abundance. The good news is that they’re announcing a full retail service network in early 2026, and they’ve already partnered with mobile service company Velofix.

Another concern for some riders is drivetrain efficiency, essentially, how much of your pedalling effort actually reaches the rear wheel. Because this is a series hybrid system, it converts your pedal power from mechanical energy to electrical, and then back to mechanical again, which naturally introduces some losses.

I’ve estimated you’ll lose around 15% in the generator and power electronics, another 15% through the controller and drive motor, and roughly 5% through the final belt drive. Add that up, and you’re looking at about two-thirds of your pedal power actually reaching the rear wheel (roughly 69% overall efficiency).

But remember, efficiency here isn’t just about how much of your leg power reaches the wheel; it’s about how the whole human-bike system uses and recovers energy. With regen braking feeding energy back into the battery, plus a big battery pack and smart power management on top, I don’t see any reason it couldn’t hit that claimed 100-mile range with the right rider and conditions.

What’s the ALSO TM-B?

The Rivian eBike.

The new Rivian eBikes feature 120mm of front and rear suspension travel, a motor that delivers roughly twice the torque of a typical eBike, and a large 808 Wh battery that provides a theoretical range of 160 kilometres per charge (a smaller 538 Wh option is also available that will do 100km).

The battery supports 240-watt fast charging, so the pack can charge from 0 to 80% in under 2.5 hours. The battery is also a massive power bank, which means it can charge any USB-C device you plug into it.

The TM-B is not a light bike. It weighs in at around 38 to 40 kilograms, which is about three to five kilos heavier than equivalent eBikes with similar batteries, suspension, and drivetrain layouts. That extra weight makes it a bit harder to maneuver, but fortunately, there’s a walk mode that helps you push it up stairs, so at least you don’t have to carry it.

When it comes to performance, there is no shortage of the stuff. With its motors producing up to 180 Nm of torque, it’s far more punchy than a typical eBike motor, making it ideal for steep off-road climbs or fully loaded cargo setups.

Rivian eBikes for Cargo Hauling

ALSO also unveiled a cargo bike at their recent launch event, and honestly, I think these four-wheeled cargo machines are more exciting than the eBike.

Here’s why. Last-mile delivery, which is the final leg of a parcel’s journey from a distribution hub to your door, accounts for around 30% of all CO₂ emissions in the logistics industry. It’s terribly inefficient.

These cargo quads are purpose-built for that job. They fit within bike lanes, which might stir up some debate, but in my view, every delivery driver using one of these instead of a van means less traffic, less noise, less pollution, and fewer parking spaces needed in our cities.

If the price is right, I can see these ALSO delivery quads becoming a common sight across dense cities around the world, and it seems Amazon agrees, because they’ve already placed an order for thousands.

Summary

Rivian’s new eBike drivetrain, with its digital gears, brings some fresh innovation to the micromobility space. But is this the future of bike drivetrains?

It really depends on the use case. For high-performance riding, this system is too heavy and not efficient enough to compete with other eBikes. But for everyday riders, the benefits are hard to ignore: automatic shifting, seamless power delivery, and a super intuitive ride feel that blends elements of eCVT and Digital Drive systems.

I just hope ALSO keeps their proprietary parts and service centres easily accessible to customers; the last thing we need is another eBike brand where support becomes a barrier.

If you’re interested in learning more about drivetrain tech like this, make sure to check out my articles on Digital Drive and eCVT systems.