Radio 4 Join the Bike Helmet Debate

[flecc]

Can the hill climbing ability not be improve without the need of increased power?

Not really, there is a direct relationship between motor watts, speed and climb ability. At a given speed, double the steepness needs double the watts, no getting round that.

Drive through the gears motors manage to some extent with lower speed down to a point, but below 6 mph isn't practical on two wheelers. The 250 watt Panasonic unit bikes are already down to about 5 mph on the steepest hills for even moderately fit riders.

Hub motors just have to rely on watts. Doubling to 500 watts rating would be sensible and cope with just about anything on proper bikes. A horse carries one rider at up to bike like speeds and one horse power is 746 watts. China with their scooter like e-bikes use around 700 watts, but I don't think we need quite that much.
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[NRG]

Can the hill climbing ability not be improved without the need of increased power?

Yes, with hub motors in mind, it means using a smaller wheel, however, this will also lower speed. Motors are wound for a voltage and wheel size to achieve a desired RPM which directly relates to speed.

If wheel size cannot be lowered the only way to climb hills better is to increase power by providing more current for the motor. You can only go so far though as the nylon planet gears and motor wire current capability etc will ultimately limit what the motor can take before failure.

The 250w Bafang motors seem to be able to handle 1Kw peaks for short periods but that sort of power would soon cause a failure if continuous.

 

[onmebike]

Not really, there is a direct relationship between motor watts, speed and climb ability. At a given speed, double the steepness needs double the watts, no getting round that.

Drive through the gears motors manage to some extent with lower speed down to a point, but below 6 mph isn't practical on two wheelers. The 250 watt Panasonic unit bikes are already down to about 5 mph on the steepest hills for even moderately fit riders.

Hub motors just have to rely on watts. Doubling to 500 watts rating would be sensible and cope with just about anything on proper bikes. A horse carries one rider at up to bike like speeds and one horse power is 746 watts. China with their scooter like e-bikes use around 700 watts, but I don't think we need quite that much.
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Maybe a dual power hub with a spirit level device that only allows increased power on hill's is needed? Thanks for explaining that.

 

[flecc]

Maybe a dual power hub with a spirit level device that only allows increased power on hill's is needed? Thanks for explaining that.

There are dual power hub-motors which can be switched, though they can be very greedy for amps in their high power mode, the old problem that designing for two ends means compromises.

That said, I think a normal hub motor with a 500 watt rating with a manufacturer seal on the controller box to prevent tampering is a better option. This would look after the illegality problem by being easily detectable if interfered with. Buyers shouldn't object to this considering the extra power they had available with this solution.
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[Old Timer]

One could say that if not really 100% fit enough to ride an E bike then get a 50cc scooter and of course I could do just that or larger because I have had a full Motorcycle licence for almost 50 years but it just isn`t the same as cycling along at a steady pace through the country lanes creating no pollution (or very little from a charge)

 

[Old Timer]

True enough, onmebike. If my leg starts to grow back, I'll let you know...

But exercise in general is a Good Thing, for amputees as for anyone else, and viz a viz electric bikes (powerful and less so) it's all about approach - use it like a moped and you probably won't improve your fitness.

Which is why I started that thread about it being so hard to PEDAL my Wisper! I want exercise, I enjoy mobility, but a powerless bike is just too difficult; I want(ed) the electric bike as a compromise, and it works. I keep the power as low as I can (so rarely on High, usually on Medium), and I keep the gearing as high as possible, too, giving me (in my old grandfather's words) "something to push against".

(Mind, Old Grandfather was writing in his diary in about 1890 when he was cycling round northern India on a bike he described as having 'neither gears nor brakes', so what he'd have thought about our Wispers and Kalkhoffs, I don't know.)

Allen.

Well! I take my hat off to you Allen and others with a missing leg or similar that are prepared to ride as you do. I see my riding as not just keeping fit but from a mental point of view I get a big lift after a ride.