Electric motor query - power and torque

Rob Graham · 2016-05-28T20:38:00+00:00

I'm looking at buying and electric bike - at 70+ I need a bit of assistance ! I was an electronics engineer so am reasonably aware of electric motor powe r, and also what torque is. But can someone care to give me this further b it of mental assistance on the motors that are used in bikes. My problem i s that there is a power limit in the UK of 250 watts - I believe also that they are meant to cut out above 15mph but that's a different matter. Where I am struggling is that I am being offered bikes with 40 NM motor torque an d up to 80 NM. Mechanics were never my strong point, so there is probably some simple answer to this, but I am seeing radial force as being related t o power in, so how can there be a 2 to 1 ration between different motors? Thanks

May 28, 2016 43 Replies

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DJC 10 years ago

If you can take opposite from the map why not adjacent?

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The Natural Philosopher 10 years ago

In reality a sextant or theodolite can do any of the above

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Roger Mills 10 years ago

Indeed. And it might save a lot of angst if we specified gradients in terms of angle with the horizontal - so my 15% slope would simply be 8.6 degrees - although at small angles like that, there's little difference between sine and tangent.

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PeterC 10 years ago

Of course! Not thinking - too long in The Malt Shovel Tavern!

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