PW-X2 Power / Torque curve

[Jackware]

Screengrab from EMTB's latest 1.04 hill climbing series, though only the EXPW mode releases the full 80Nm

 

[gdcase]

Guess it makes sense to keep the cadence 100+ for optimum performance!

 

[TPEHAK]

At 100 RPM I lost my steam pretty fast. What I found is high cadence support is helpful only if you go on highest gear to reach highest speed. This is good for fast commuting of flat smooth ground.

 

[gdcase]

Yea, me too @100. From the chart it appears that anything over ~85 give some benefit.

 

[Dave_h34]

The torque curve is the important one which says keep below 60rpm for max input from motor. The continued rise of the power curve is a result of increasing revs, the torque is falling. At peak power the motor is contributing ~65Nm which is obviously less than the 80Nm the motor can give.

 

[Olof Bike Adventures]

To get the most out of the motor it is power that is interesting (work done per unit of time ).

 

[Olof Bike Adventures]

Just another point I want to make. Peak power can only be maintained for a few seconds, so this chart is a bit misleading.

 

[Pdoz]

Contrast to the okd (2018) pwx1 graph that dropped torque noticeably around 80 cadence

Having owned both, the pwx2 is more versatile but it's definitely not a deal breaker - both are great motors.

PS giant tunes them for 85 nm torque so the power figures need adjusting up appropriately

 

[Pdoz]

Just another point I want to make. Peak power can only be maintained for a few seconds, so this chart is a bit misleading.

The torque curve is the important one which says keep below 60rpm for max input from motor. The continued rise of the power curve is a result of increasing revs, the torque is falling. At peak power the motor is contributing ~65Nm which is obviously less than the 80Nm the motor can give.

Have either of you ridden the yamaha at full output over extended periods?

I have a shuttle run that I do regularly -350 m elevation over 3 km, the final km is particularly steep but still just a gravel road so no skill needed. I've done it multiple times with both the pwx1 and pwx2 , BOTH are faster up that hill when I keep cadence in the 70-80 range, the pwx2 is even faster if I aim cadence >95 but drop back into the torque curve as it gets steeper.

 

[Olof Bike Adventures]

Have either of you ridden the yamaha at full output over extended periods?

I have a shuttle run that I do regularly -350 m elevation over 3 km, the final km is particularly steep but still just a gravel road so no skill needed. I've done it multiple times with both the pwx1 and pwx2 , BOTH are faster up that hill when I keep cadence in the 70-80 range, the pwx2 is even faster if I aim cadence >95 but drop back into the torque curve as it gets steeper.

If the chart was static (that peak power can be maintained for that hill climb of yours), a cadence of 105 would take you to the top the quickest, simple math. But as I wrote in my second post, peak power can only be maintaned for a few seconds until the power tapers off. Then the power curve looks different.

What causes the power to taper off is really the current (that is proportional to the torque) that generates heat => thermal loss in the motor, batteri (incl BMS) and the motor controller.

What you say that you are faster with a lower cadence in real life, is probably true.

And no, I have sadly not tested any Yamaha motor, but what I said was generic for all brands. Would love to test one, though!