As I’ve shared in the past, my day job is writing about e-bikes to an audience that mostly are not cyclists. I love this job because I’m getting to make the tent bigger, so to speak. There’s a big piece of my job that is service journalism—how-tos and what-fors—so I find myself explaining things that most of you in our audience stopped thinking about years ago.
But the e-bike world is a rapidly changing space and I’ve recently gotten questions from friends about the differences between some Class 1 e-bikes, particularly with eMTBs. The question, when stripped down to its most basic level is: If all Class 1 e-bikes are limited to a maximum assist speed of 20 mph, what’s the difference between some of the different motors? Put another way, why would someone care whether a motor produces 450W or 600W if it’s still going to stop assisting a rider at 20 mph.
The crazy thing is, there can be quite a difference. When looking at eMTBs, there are four different numbers that are worth considering. The first is nominal wattage: This is how much power the motor can produce continuously, its version of Zone 2. For most motors, that figure is 250W. The second important number is how much torque the motor produces. That generally ranges between 55Nm and 90Nm for the motors being spec’d in eMTBs. The third number is peak wattage, which can range from 450 to 600W. The fourth number is total e-bike weight.
Also, all of these motors are mid-drive motors, not hub motors. There are no high-performance eMTBs I know of that use a hub motor.
With eMTBs it’s not often that you’ll be going 20 mph, so differences in motor power come out in acceleration, climbing and in technical terrain with lots of rocks or roots.
So here’s a bit of comparison:
- Bosch Performance Line CX: 250W nominally, 85Nm of torque, 600W max
- Shimano EP801: 250W, 85Nm of torque, 600W max
- Shimano EP8: 250W, 85Nm, 500W max
- Specialized 2.2: 250W nominally, 90Nm, 565W max
- Specialized 1.2: 250W nominally, 50Nm, 320W max
- Bosch Performance Line SX: 250W, 55Nm, 600W max
- Fazua Ride 60: 250W, 60Nm, 450W max
- Yamaha PW-X3 is in this neighborhood
As motor wattage goes up, battery size needs to go up to keep range constant. Most motors weigh around 3kg/7 lbs., but the lightweight ones, like the Fazua Ride 60 and Bosch Performance Line SX weigh more like 2kg/4.4 lbs.
For most riders, if you’re out on your own, you won’t notice a difference between the Shimano EP8, EP801, Bosch Performance Line CX vs. SX or the Specialized 2.2. You’re more likely to notice the reduced power of the Fazua Ride 60. But here’s the thing: We’re seeing the Performance Line SX, the Fazua Ride 60 and Specialized 1.2 motors on eMTBs that weigh less than 40 lbs. EMTBs with the Performance Line CX, Shimano EP8 or 801 and Specialized 2.2 tend to weigh closer to 50 lbs.
To a certain degree, these differences are academic until you start riding with friends. In steeper terrain, people are finding that an eMTB with the Bosch Performance Line CX or Shimano EP801 will outclimb the other bikes, but with the weight loss that the Bosch Performance Line SX those lighter eMTBs can often keep up.
The stronger the rider, the less difference peak power makes. If the hills tend to be shorter, steeper and punchier, you want more torque. If the climbs are longer and they are smooth enough that you can climb at a high pace, more wattage is the thing. The more technical the trail, the more valuable maneuverability becomes and the lighter motors begin to shine.
There’s one caveat to all this though as far as riding with friends goes: If riders aren’t in Turbo or Boost mode, the max PAS level, you’re not going to see these differences.