Where can I purchase a torque sensor for a project bike? I have purchased a "replacement" torque sensor for a Giant bike, but I can't figure out how it works. Does anybody have any ideas on how to build a simple and reliable torque sensor?

Thanks for any help,

John

No easy way to do this, that is the problem.

Torque sensors for electric bikes are usually electromagnetic materials integrated with the hub. Once you manage to set this up, you then need to make a programmable circuit that reads the torque coming in from the sensor and then adjusts the gating voltage on a MOSFET hooked to the motor. As mentioned, this isn't a trivial task.

I've revived a thread on Pedelecs.co.uk, which should provide some info (with lots of photos of existing systems):

https://www.pedelecs.co.uk/forum/elec...html#post62512

Cheers, Dan

Probably a dumb idea but, I wonder if instead of trying to sense torque, a simple pedal mounted pressure sensor would work? I'd think there's a direct relationship between pedal pressure and applied torque. Then again, it would need a WiFi or Bluetooth interface to be useful.

You'd have to somehow not activate the motor if you're just standing on the pedal while coasting.

Fine if you combine the signal from a conventional cadence sensor (Hall-effect + ring of rare magnets) with that of the torque-sensing device. You'd need to be able to program the controller though.
Cheers, Dan

Another possibility for a pressure sensor, for recumbents only, would be a lumbar cushion sort of thing. At least that way there's no issues with running wires to the throttle. With my Rans Stratus, applied pressure on the pedals is pretty much opposed by the seat back.