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Old 01-25-20, 02:59 PM
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Barrettscv 
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Join Date: Feb 2006
Location: Lake Geneva, WI
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Bikes: Ridley Helium SLX, Canyon Endurance SL, De Rosa Professional, Eddy Merckx Corsa Extra, Schwinn Paramount (1 painted, 1 chrome), Peugeot PX10, Serotta Nova X, Simoncini Cyclocross Special, Raleigh Roker, Pedal Force CG2 and CX2

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Originally Posted by Leisesturm View Post
I think this thread would be much more helpful if all the acronyms being used were written out in full at least the first time they are used. I've dabbled in this e-assist stuff since the early and mid-90's and I'm seeing acronyms in this thread I've never seen before. Never got further than paper napkin flow charting though. Back then Ni-CAD batteries were still a thing. Throttle was still king but some crude torque sensors had appeared. That's all changed and it doesn't look like Li-ion battery technology is going to be improved upon in my riding lifetime. About my only question is: how is it possible to have a torque sensing crank drive system? It seems like the motor assist turning the crank would make it impossible for the torque sensor to know just how much human input into the system is going on. Back when I was designing systems on napkins I ruled out both torque sensing and crank drive together for that reason. Clearly I was wrong. But why was that?
I agree that acronyms should be explained, as you outlined.

Torque sensing is achieved by using strain gauges, see: https://www.omega.com/en-us/resources/strain-gages . It's not difficult to measure the torque developed by the cyclist and isolate it from the torque developed by the electric motor. The torque developed by the motor is transferred directly to the chainring. The torque developed by the cyclist is measured in the axle between the crank arms.

Think about a tandem bicycle: The power developed by each rider is measurable and is independent. Now imagine that the captain is human and the stoker is electric and the stoker produces power in a proportional response to the power produced by the captain.
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Last edited by Barrettscv; 01-25-20 at 03:51 PM.
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