Rumours had been swirling for years that Rivian was secretly building bicycles, and now it's official. The EV brand is stepping beyond cars and trucks and into the 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.
Deep Dive into the ALSO Drivetrain
My plan for this article is to focus primarily on the drivetrain, as 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 futuristic drivetrain tech similar to this.
Let's now analyse the drivetrain and figure out what makes this system so different from everything else on the market.
The Innovative Series Hybrid System
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 website 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 they are on a normal e-bike. So when you pedal, you're actually turning a generator. That generator then sends your pedal power to the motor and battery while digitally recreating the feeling of a chain with really impressive accuracy.
I know a "digital chain" sounds like something from the future, but the tech is actually quite old. 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.
Key Advantages of the ALSO Drivetrain
Let's now look at the advantages of this bike's 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 draw card is the automatic shifting with unlimited effective gear ratios. There's no clunking you might associate with gear changes; rather, the bike changes speed smoothly and quietly.
You just pick your preferred cadence, and the system will change the bike speed based on how hard you're pushing the pedals. That should result in a great user experience for novice cyclists. If you prefer full control, the TM-B also offers manual digital gears. You can instantly change gears anytime under a full pedal load.
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 you're slowing down, extending range and drastically reducing brake wear.
And since Rivian 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 completely decoupled, the battery is no longer removable, and, of course, there is an alarm, and you can easily find it with GPS tracking.
The Strategic Choice of Belt Drive
You might be wondering why the TM-B sends power to the rear wheel via a belt when it could just send the power straight to a rear wheel motor instead. Well, one big reason is torque. The TMB multiplies the motor's torque through a combination of internal gearing and the external 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 the ability to climb steeper hills. With a rear hub motor, you simply can't take advantage of the same kind of gear reduction. Rear hub motors handle everything directly, which means they can't always operate in the most efficient RPM range, especially when you're switching between steep climbs and flat sections.
I've actually simulated a comparison between the TM-B motor and a heavy-duty 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 and without overheating, while the heavy-duty hub motor would be limited to a 7 to 10% grade. There's a handling advantage, too. Because the motor sits in the middle of the bike rather than at the rear wheel, the 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, better handling, better acceleration, better suspension, and better traction.
Potential Drawbacks
Let's now take a look at the disadvantages. 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 that 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 makes it to 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 2/3rds of your pedal power actually reaching the rear wheel. But remember, on an ebike, efficiency isn't just about how much of your leg power reaches the rear wheel. It's about how the entire 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.
Specifications and the TM-Q Delivery Quad
The new Rivian eBikes feature front and rear suspension travel, a motor that delivers roughly twice the torque of a typical ebike, and a large 800 Wh battery that provides a theoretical range of 160 km per charge. The battery supports 240 W 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 you can charge any USB-C device that you plug into it. The TM-B is not a light bike. It weighs in at around 38 to 40 kg, which is about 3 to 5 kg heavier than the equivalent ebikes with similar batteries, suspension, and drivetrain layouts. That weight makes it a bit harder to maneuver, but fortunately, there's a walk mode that helps you push it upstairs, so at least you don't have to carry it.
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 the 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 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.
Conclusion: The Future of E-Bike Drivetrains?
Rivian's new eBike drivetrain with its digital gears brings some fresh innovation to the micromobility space. But is this really the future of bicycle 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 an eCVT and digital drive systems. I just hope that Rivian makes their proprietary parts and service centres easily accessible to their customers because the last thing we need is another eBike brand where support becomes a barrier.
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