First 100 miles on my E-Bike

Re:First 100 miles on my E-Bike by CydeWeys on Saturday December 30, 2017 @11:50AM (#16036012)

Are those two figures comparable though? Is an electric bicycle motor measured by its power draw or by its output? And either way, it's still not the same because at most that'd be measuring at the crank, whereas an ergometer measures at the pedal. So if I had to guess I'd say that a 1000W electric motor is roughly equivalent to, say, 500W output from a human on an ergometer (which of course is still way better than the average person can perform for any length of time).

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Re:First 100 miles on my E-Bike by revelation on Saturday December 30, 2017 @12:22PM (#16036179)

It's hard to build an inefficient electric motor, and I'd think the headline figure is the motor power rating.

But even if we assume it's the power draw and the motor itself is terribly inefficient, we're still talking 80% efficiency? Chain drive is 95% efficient if badly maintained, but then the human power loses that, too, so we don't need to consider it. So we're still talking 800W, which is 3-4 times as much as needed to sustain 20 mph on flat ground, and utterly out of range of any human for any time period beyond a minute.

The power and speed limit of normal ebikes is a feature. It keeps us from making the same mistake we have with cars, which only ever got faster while driving discipline declined and were at any point beyond human ability anyway.

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Re:First 100 miles on my E-Bike by Decade on Saturday December 30, 2017 @03:24PM (#16037321)

Correction: The headline figure is the motor’s maximum power rating. I tried an electric bike with a 350W hub motor, and on a moderate hill it did not have enough torque to move. Power = Work ÷ Time, Work = Force × Distance; 0 distance ⇒ 0 power.

I understand that mid-drive motors can deliver much more torque than hub motors. Maybe the OP is being realistic about what he needs in the Arizona hellscape where he lives.

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