Wireless Crank power meters as torque sensor?

[DanGT86]

Been seeing a lot of wireless bluetooth crank spider power meters on the market lately. Has anyone deciphered these major manufacturers' communication such that we could use them as torque sensors for ebikes? They send out torque and cadence info to computers, displays, and I think wearable ride trackers. I wonder how encrypted those signals are. I have no knowledge of how to do this but would not be surprised if one of you wizards has figured it out.

It would be really nice to be able to just adapt one of these crank spiders to any crankset and bottom bracket and not be stuck with the limited torque sensing BB options currently offered.

 

[amberwolf]

There's been a few threads over the years starting discussions on these, but nothing finished on any yet; here's a few:

Universal torque sense

These Stages power meter crank arms output a power signal via bluetooth LE that Garmins and other various bike computers receive and display. Seems like an e-bike controller could be made to receive that same signal and use it for torque sense. Maybe even some of you firmware developers could...

endless-sphere.com

Using crankset with ANT+ powermeter as PAS

Hello everyone, first post here. I'm halfway through my first build and I've made it as far as I can without taping into the wealth of knowledge that is Endless-spere. Lets get to the heart of the issue: My goal is to setup a cyclocross frame as a single speed with PAS, a rear hub motor, and...

endless-sphere.com

Is there a reliable torque sensor?

I've been using T9 BBs with some success and lots of failures. I've got a stack of dead ones. I have a couple T17 BBs "out for delivery" right now but I'm wondering if I should rethink my approach. The more I read about torque sensors, the more I notice comments about how bad the designs are...

endless-sphere.com

and this one with hub-sensing solutions for freehubs or freewheels, that could be adapted to many possible parts in the chainline, in addition to using on a regular bicycle wheel.

Rear all axle v3 with torque sensor

https://ebikes.ca/product-info/grin-products/all-axle-hub-motor.html Came out in the Christmas newsletter. Super stoked to see the torque sending quality

endless-sphere.com

 

[DanGT86]

Thanks. Bummer to see nobody has really completed it yet. I wish I had the time and skill.

I really like the idea of a crank spider containing all the torque sensing and wireless guts. That seems like the most universal option.

Only major downside is that I hate the idea of having to remember to plug in and recharge and essential part of the bike drivetrain. Way less of an issue on an ebike but still annoying to have to remember. Need to make one that charges off of rotation or movement like a rolex.

 

[amberwolf]

I could learn the skill (am working on something much harder right now, the Snuggles The Wolf robotics project elsewhere on ES) but time is just...yeah.



For charging, you can install wireless charging coils on the device, and a matching one on the frame, and wire the system to your charge port so it's powered by the charger (but doesn't drain your traction battery).

Some random google and amazon results for the basic parts (you'd need more than this to do it)

wireless charging coils - Google Search

www.google.com

https://www.amazon.com/Wireless-Charging-Coil/s?k=Wireless+Charging+Coil