BBSHD specified speed (RPM) - too fast?

[JayCee]

I've read from several reviewers that the BBSHD is mis-geared, in that the optimum speed at peak power requires something like a 150RPM cadence. True? What roughly is the specified output cadence at the pedals (via kV) of a BBSHD at 52V?

 

[LyonNightroad]

IIRC, Typically peak torque is produced on most brushless motors at 50% of no load speed.

I did some informal experiments with my bbs02

In terms of efficency, on my bbs02, using 300 watts current limiting and verified with a watt meter, regardless of if I was in first gear (allowing the motor to spin too fast to pedal) or fifth gear (a very nice slow cadence), the speed I achieved for the same number of watts, was always the same on the same stretch of road. Which is to say you can set the PAS to a low cadence with trivial loss of efficiency.

 

[Chalo]

IIRC, Typically peak torque is produced on most brushless motors at 50% of no load speed.

That's max power at about 50% of no-load speed. Max torque is at stall. Max efficiency at close to 80% of no-load speed. These figures assume a "dumb" controller that doesn't modulate torque delivery.

 

[LyonNightroad]

Ah, So is it the current limiting from the controller that causes the motor to feel like it is generating roughly the same torque from stall until it it begins to drop off at a certain RPM?

 

[riba2233]

Ah, So is it the current limiting from the controller that causes the motor to feel like it is generating roughly the same torque from stall until it it begins to drop off at a certain RPM?

Yep

 

[Chalo]

Ah, So is it the current limiting from the controller that causes the motor to feel like it is generating roughly the same torque from stall until it it begins to drop off at a certain RPM?

Motor phase current limiting would have the effect you describe. I don't know whether that's a feature of the controller we're discussing.