So, you’re getting serious about choosing an e-MTB. If you’re at least a little familiar with conventional mountain bike technology, you probably have a good idea of how much suspension travel you want. Typically, a lot of spec decisions go hand-in-hand with that one differentiator. Before you know it, you’ve settled on an enduro bike for downhill shredding or a short-travel bike for efficiency, for example.
An electric-assist motor adds another dimension to your decision-making process, and it isn’t immediately intuitive if you’re new to the technology.
Roughly speaking, the industry has settled on two types of e-bike motors for mountain biking: Full-power and lightweight. Seriously, you could not come up with more vague and confusing terms for these options, but there we are.
Bike brands can put either of these motor types in any sort of mountain bike chassis. You’ll often find long-travel e-MTBs with full-power motors and shorter-travel bikes with lightweight motors. That isn’t always the case though. For example, Specialized offers a lightweight SL motor trim for its Kenevo enduro bike.
No matter the chassis package, what you need to know is that there are three major differences between full-power and lightweight e-MTBs: Power delivery, battery life, and weight.
E-Bikes By the Numbers
More and more bike companies are offering both full-power and lightweight e-MTBs. Just looking at a few popular brands bikes side-by-side shows you the differences between the two options. It also shows how brands opt for a range of different motors, depending on what their engineers want.
| Bike | Motor | Torque | Watt hours |
| Specialized Turbo Levo | Turbo 2.2 | 90nm | 700wh |
| Specialized Turbo Levo SL | Turbo SL 1.1 | 35nm | 320wh |
| Trek Rail | Bosch Performance CX | 85nm | 750wh |
| Trek EXE | TQ HPR50 | 50nm | 360wh |
| Transition Repeater | Shimano EP8 | 85nm | 630wh |
| Transition Relay | Fazua Ride 60 | 60nm | 430wh |
| Orbea Wild | Bosch Performance CX | 85nm | 750wh |
| Orbea Rise | Shimano EP-801 | 60nm | 360wh |
Power Delivery: How does the bike feel when accelerating?
Looking at the table above, torque is the most meaningful spec to consider when you want to understand how an e-bike’s motor feels as it accelerates out of a corner or a slow section of trail. Torque is measured in Newton Meters (Sir Isaac … ever heard of him?). Essentially, it’s a measure of rotational force.
So, in the lightweight camp, you have bikes with torque between 35 and 60nm. Full-power e-bikes offer almost twice as much torque: 85-90nm.
It’s like driving an on-ramp onto a highway: In a Camaro, you’re up to 65mph way faster than if you’re driving a Camry, but the speed limit is the same.
It’s a bit of an oversimplification to look at two bikes side by side, and assume that one with 60nm of torque will accelerate quicker than one with 50nm. It might. However, motor manufacturers can tune their drive units to respond in a range of ways, making them extra punchy or mellow and smooth. Also, motors have different ways of delivering power to the bottom bracket spindle. Trek is especially proud of its TQ motor, which uses a Harmonic Pin Ring system.
But we don’t have time to go down that rabbit hole. Essentially, if you want as much pedal-assistance as possible, on demand, a full-power bike might be best for you. You can always toggle between e-assist settings to tune it down if you’re feeling mellow. Generally speaking, the motor characteristics of lightweight e-bikes feel more “natural” — a smoother assist that makes it feel more like a conventional mountain bike. And remember, all of these bikes are Type 1 e-bikes, so their max electric-assist speed is 20mph.
Battery Life: How Far Do You Want to Roam on the Range?
The second notable spec on that table is watt-hours. Essentially, that number is a measure of how many watts (i.e., power) the motor can sustain for one hour. Of course, there’s practically no mountain bike ride scenario where you’ll have an Orbea Wild sustaining 750 watts for 60 minutes. It’s just a handy, standard for comparisons.
Full-power e-bikes clearly have higher-capacity batteries. So they could last longer than lightweight e-bikes … could. But remember, these full-power bikes are producing a lot more torque. In case you don’t have it memorized, a key factor in the torque equation is force — a.k.a. power. The motor demands more wattage, hence the battery needs to be bigger. So, if you’re a turbo-happy rider, that big battery might not do as well as you’d expect on a hard route with a ton of climbing.
Also of note, some companies offer range booster batteries, which cleanly integrate with a lightweight e-bike. They usually fit into the bottle cage and plug right in to offer another 150-ish watt-hours. So, you can extend a lightweight bike’s range, but it isn’t quite as clean and self-contained as a full-power e-bike with a high-capacity battery.
Weight: Do You Want It to Feel Like a Conventional MTB?
I didn’t list bike weights in the table, because that can vary based on the parts trim on a given bike. All of those models are offered with entry-level builds that certainly have a few extra pounds compared to the top-of-the-line bikes with carbon fiber everything.
As I mentioned earlier, many brands opt for full-power motors on enduro-spec bikes and lightweight motors on trail bikes. But in a nutshell, you can expect a full-power e-MTB to weigh about 8-10 pounds more than a lightweight e-MTB, assuming the same builds. That will make it a bit harder to get off the ground, a more planted feel, if you’ll excuse the cliche.
Some brands take pride in sourcing custom, super light batteries to shave grams. Orbea’s Rise is an example of this trend toward third-party batteries. While a Shimano motor supports this, Bosch, for example, is a closed system that can only work with Bosch batteries and components. That’s another topic to table for a more in-depth future article.
Conclusion
I’ve ridden a handful of both lightweight and full-power e-MTBs, but I don’t think I’ve ridden enough to feel strongly about one or the other. I really enjoyed my time on the Specialized SL 1.1 motors. The Levo and Kenevo are both really dialed, and I felt immediately comfortable on them.
However, even with a booster battery, I felt a bit of range anxiety on these lightweight motors. When it’s the middle of summer and I want to do a big ride, I’d hate to feel limited to just 3 or 4 hours.
The Bosch CX motors I’ve ridden are also fantastic. These are exclusively full-power bikes, and even though the system is massively powerful, it delivers that power very smoothly. And — unrelated to this article’s specific topic — I found Bosch motors have minimal motor lag. I need more time on these bikes to have a verdict on their range capabilities. But if they gave me another hour of riding in normal conditions, I could be sold on full-power.
What do you ride? Let me know in the comments, or drop any questions in below, and I’ll do my best to get you an answer!
P.S. We use affiliate links here at Direct Current. If you’re considering buying a Specialized, we’ll get a little kickback if you purchase using a link from this story. 😀