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Power curvesHow the E-MTB motors work

EMTB Magazin

 · 14.05.2018

Power curves: How the E-MTB motors workPhoto: Markus Greber
Power curves: How the E-MTB motors work
Which motor is the best? The answer depends heavily on your own rider profile. The performance curves of the engines show the characteristics and ideal working ranges of the engines.

The question of maximum power comes up like a never-ending mantra. However, the naked motor power is only half the truth. The maximum power development varies depending on the cadence and pedalling power. For person A, a different motor can therefore promise the greatest propulsion than for person B. Or to put it another way: someone who rides at a high cadence is better off with motor A, while someone who pedals slowly and comfortably is better off with motor B.

The roller test bench in the EMTB test laboratory makes comparable and repeatable measurements possible. All motors were subjected to the same test procedure.Photo: Markus Greber The roller test bench in the EMTB test laboratory makes comparable and repeatable measurements possible. All motors were subjected to the same test procedure.

We ran all the test motors over our roller dynamometer and measured the power output of the motors at full assistance, a riding speed of 15 km/h, with cadences between around 60 and 100 rpm and with rider pedalling power of 100, 130, 160, 190, 220 and 250 watts. The deviations in the cadence gradations are due to the different gear ratios of the test bikes.

Bosch Performance XC

The power of the Performance CX motor (y-axis) as a function of the cadence and the rider's pedalling power (x-axis).Photo: BIKE Magazin The power of the Performance CX motor (y-axis) as a function of the cadence and the rider's pedalling power (x-axis).

Brose Drive S

The Brose motor pushes strongly even at low pedalling power and even delivers slightly more power at low cadence (blue curve) than at higher cadence (red curve). The green curve is only of limited relevance in practice, as the cadence is extremely high at 110 revolutions.Photo: BIKE Magazin The Brose motor pushes strongly even at low pedalling power and even delivers slightly more power at low cadence (blue curve) than at higher cadence (red curve). The green curve is only of limited relevance in practice, as the cadence is extremely high at 110 revolutions.

Rocky Mountain Powerplay

The Powerplay motor has its greatest power development at pedalling power between 160 and 220 watts. The Rocky motor delivers a lot of power even at a low pedalling frequency (blue curve).Photo: BIKE Magazin The Powerplay motor has its greatest power development at pedalling power between 160 and 220 watts. The Rocky motor delivers a lot of power even at a low pedalling frequency (blue curve).
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Shimano STEPS E8000

The Steps 8000 motor delivers a very even power output and hardly makes a difference whether the rider is pedalling hard or comfortably. The higher the cadence (green curve, 90 rpm), the stronger the Shimano motor pushes. At a lower cadence (blue curve, 58 rpm), it delivers less power.Photo: BIKE Magazin The Steps 8000 motor delivers a very even power output and hardly makes a difference whether the rider is pedalling hard or comfortably. The higher the cadence (green curve, 90 rpm), the stronger the Shimano motor pushes. At a lower cadence (blue curve, 58 rpm), it delivers less power.

TQ

The TQ motor delivers enormous power, even at very low pedalling power. As the cadence increases, the power output decreases. The TQ motor only provides limited support at very high cadences above 90 (purple curve).Photo: BIKE Magazin The TQ motor delivers enormous power, even at very low pedalling power. As the cadence increases, the power output decreases. The TQ motor only provides limited support at very high cadences above 90 (purple curve).

Yamaha PW-X

Yamaha's PW-X motor only delivers its full power at medium and low cadences (red and blue curves) at pedalling power from 160 watts and then works very evenly and smoothly. The purple curve stands for a cadence of an extremely high 105 revolutions, so it has little practical relevance.Photo: BIKE Magazin Yamaha's PW-X motor only delivers its full power at medium and low cadences (red and blue curves) at pedalling power from 160 watts and then works very evenly and smoothly. The purple curve stands for a cadence of an extremely high 105 revolutions, so it has little practical relevance.
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