It is hard to choose poorly on a torque sensing motor these days if you stick with the latest mid drives from the big three - Bosch, Brose and Shimano. Keep in mind that the most raw motor power may not, in fact, be the most important thing for your experience. Smoother riding, less powerful, longer range motors will still get up a steep, just a little slower. With the same battery, the hare might win the hill, but the turtle will always finish the race. Overall bike weight can also have a major impact on steep climbs - aka power to weight ratio - which is why a motorcycle will beat a supercar in a quarter mile race. And finally., eBikes are still bicycles - advanced mid drives only multiply your input, not replace it.
In real world testing on the steepest of hills (with equal rider wattage input), here is the descending pecking order of the fastest climbing eBike motors, from most fastest to the most tame:
Bosch's most powerful motor is tuned for climbing trails fast, and it is the top climber in real world testing on or off road. It is limited to 20mph assistance so if you need a higher top speed the Performance Speed is the way to go. The Performance Line CX drive has what Bosch calls Uphill Flow - support starts at very low pedal frequencies – this makes it easier to set off when already on a hill or to drive out of tight curves.
The S motor line is at the very front of the big dog pack - dramatically peppier than most competing systems, with 15% more power than the already strong Brose T. Pushing 90nm of torque and 550 (560 for the Mag version) peak watts, and applied with the signature Brose smooth/natural feeling and low noise/vibration. Specialized uses the S motor but calls it "Turbo 1.3" or “Turbo 2.1” (Mag) and there's an app that you can tune motor performance via bluetooth on your smartphone.
The Performance line is Bosch's most powerful street motor is tuned for a dynamic sportier ride, vs the active line's daily rider & leisure emphasis, and is the motor system to have on a premium sporty eBike. Pushing 63 Nm and available in a 20mph and 28mph versions. We just don't see any problems with the Bosch setups, so peace of mind is included.
Noticeably peppier than competing systems, the Brose T motor’s "natural" feeling power delivery hits the perfect balance between plenty of giddyup and efficiency to ensure great range. Brose uses the same motor for leisure, sporty and off road - the tuning is different to suit each experience. Torque peaks at 72nm and 520 watts, beating out both the Shimano Steps city motors and the Bosch Active line, and on par with the Bosch Performance street motors,
Shimano is getting traction with mountain bikers with the E8000 motor system that is lighter than both Bosch or Brose yet has plenty of gusto to climb hills. Shimano has impeccable racing credentials, so they have really stepped up their game to distinguish themselves with the MTB focused group. A full 2.5 lbs lighter than Bosch's Performance CX, it also has the narrowest "Q factor" and allows for shorter chainstays. Just because it is lighter does not mean it is not powerful - it has 70 Nm of torque!
Lighter and more affordable than Brose or Bosch, Shimano's newest street motor system performance is no slouch compared to the most common 20mph city oriented motor, the Bosch Active line. The new version is almost 1/2 a pound lighter than the 6000 series, and 20% more efficient - so you can expect even better range. Delivers an output torque of 60Nm (up from 50nm) for solid climbing and quick acceleration, and up to 500 watts of motor power - putting the new Steps motor in contention with Bosch and Brose for 20 mph city bikes.
Usually overlooked for its sexier siblings in the Performance line, Bosch's Active line is the bulletproof mainstay of most high quality, modern city eBikes. Especially suited for upright city cruisers, It gives just the right amount of assistance for daily commuting and relaxed tours, with the best battery range in the Bosch line. Bosch Active line is changing for 2018 but will no doubt continue to have the best in class reliability for everyday and leisure riding.
Brose produced a special motor just for Specialized’s entry level eBikes (Specialized calls it the Turbo 1.2E) It is geared toward efficiency for excellent range, while still providing plenty of torque at low rpms so fully loaded commuters can flatten their hills out, applied with the Brose signature natural feeling smoothness.
Entry level Steps E6000 is lighter and more affordable than Brose or Bosch, and the performance is no slouch compared to the most common 20mph city oriented motor, the Bosch Active line. Like Bosch, they use a proprietary battery along with their motors. Batteries for City systems are externally mounted on the back rack or frame mounted on the downtube, and on the small side at 400 watt hours. Overall the system is less bulky and lighter - and price ranges of 2-3k they lead the industry for value in a mid drive.
Note that all of the speed motors (assistance to 28mph) are not the fastest steep hill climbers. This is because power must be spread over a wider speed range. Of course a speed eBike is going to be fastest if already going 28mph when approaching an easy hill. Probably on moderate hill as well, with head start and substantial rider pedaling force. But the only benchmark metric for max raw power are steep hills.
Find out why motors perform differently