Quote Originally Posted by Agathon View Post
OK, that's certainly how I would have dealt with torque issues with a conventional motor, but I thought the whole point was that torque went down as speed increases. I see that gearing down, by say 1:2 would give twice the torque, but getting the speed up to 1800 mm/min (900rpm for the motor) for rapids will mean that the motor is well outside it's optimum torque region. Or is it the case that in practice this wouldn't be an issue?
I'm about to head out, so this is a very brief explanation.
Generally smaller motors the torque doesn't drop off as quick, especially on relatively lower voltage power supplies. Larger motors can maintain a similar torque drop, however you're into high voltage drivers, which carry an additional cost. So you can quite often get better performance from a smaller motor spun faster from a lower voltage, than you can with a large motor run from a less than ideal voltage.

And that is probably as clear as mud, but I've got to go!