Leeps wrote:Gears are better for climbing hills, however from a performance perspective the hub motor wins.
NickF23 wrote:There is also generally a differnce between a geared hub motor ie fixed gearing and direct drive hub motors.
NickF23 wrote:...looking forward to the chart
Maximum speed at 15% grade: 7 mph verses 17mph
Maximum speed at 10% grade: 15 mph verses 23 mph
Maximum speed at 5% grade: 38 mph verse 38 mph (the hub peaks here)
Maximum speed at 0% grade: 48 mph verses 58 mph
xyster wrote:I've climbed 15% (or darn near) grades at 20mph from a dead stop, and 10% grades at 26mph from a dead stop.
xyster wrote:You're also forgetting that the lower wattage output occurs at lower speeds...as the motor gets itself slowly up to speed, more power lets it climb faster...at the wheel.
But as the rpms rise you have to spread the same power across a larger number of "radians per second" so the torque actually drops as the rpms rise
safe wrote:Let's talk about Torque
The "PWM Current Warping" effect (Buck Converter) definitely has a LARGE effect on this low end torque area and this does give some credibility to the idea of using the hub motor and abandoning chains and gears. Were it not for this effect it would be impossible.
xyster wrote:How much power in watts can a bicycle chain drive system handle?
Please note (again), I'm not arguing that gears are not far more efficient over a normal range of rpms... just that high-end, available hubmotor systems can climb hills just as well if not better than high-end, available chain drive systems. If true, the power factor cancels on both sides of the hubmotor vs. chain drive equation, leaving as most important ancillary factors such as efficiency (gears/chain drive wins big time) vs. simplicity and its close cousin, reliability (hubmotor wins).
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