Direct drive growl, normal?

[anon4]

I have took my new hub from cyclotricity for a spin and it performs pretty well. Only thing is I thought DD hubs were meant to be pretty much silent? It is at high speed but it has quite a loud growl when starting up. Runs great and doesn't pull too much current so I'm confident it's set up right.

 

[danielrlee]

Yep, totally normal to hear a little growl at low RPM's if using a trapezoidal (non-sinewave) controller.

 

[anon4]

Yep, totally normal to hear a little growl at low RPM's if using a trapezoidal (non-sinewave) controller.

The controller is sinewave

 

[vfr400]

It's the commutation that you're hearing. The controller is firing pulses of power at the motor, which basically knock the motor round. It's not so fierce with a sine wave controller, but still noticeable at low speed, when the frequency is low. DD motors commutate at a lower frequency than geared motors, so the noise is easier to hear. The amount of growl you hear depends on the current, so if you don't like it, turn the power down at low speed. The growl isn't a sign of anything harmful happening, but its probably an indication that your motor is running inefficiently in that zone.

 

[anon4]

It's the commutation that you're hearing. The controller is firing pulses of power at the motor, which basically knock the motor round. It's not so fierce with a sine wave controller, but still noticeable at low speed, when the frequency is low. DD motors commutate at a lower frequency than geared motors, so the noise is easier to hear. The amount of growl you hear depends on the current, so if you don't like it, turn the power down at low speed. The growl isn't a sign of anything harmful happening, but its probably an indication that your motor is running inefficiently in that zone.

The sound doesn't bother me, was just confirming it is normal. As for efficiency I've started pedalling at startup as it's a bit slow to get going compared to geared. Just setup regen braking which should help me a little as I do plenty of descents but range seems similar to the geared hub so far, needs a longer range test to see for sure