Power meter as torque sensor?

Hello!
I've recently rebuilt an old hybrid bike into an ebike with parts from Grin and I was hoping to use it as a winter bike in a climate with snow and salt and this has led to a real headache when it comes to finding a good way to add torque sensing capability to the bike. I've tried the Sempu BBs in the past and while they work great no matter how much maintenance I did after every ride they ended up being completely gunked up by the end of the winter and spending $150+ seasonally to replace one component isn't great. I've settled for a cadence sensor in the meantime but I've continued looking into alternative solutions like cranks with torque sensors built-in or the BEAMts system which both have been dead-ends.
As such, I was wondering if it might be feasible to use a power meter and have it stream data via ANT+ or BT to a microcontroller and have it use the data from the meter to act as a torque sensor and have the data translate over to whatever protocol Grin's Cycle Analyst accepts for PAS/torque input.
I was curious if this had been attempted before and if it would even be feasible considering the potential latency and the semi-proprietary nature of of most power meters out there. Any insight or suggestions on this matter would be much appreciated!

NixyMouse said:

ended up being completely gunked up by the end of the winter and spending $150+ seasonally to replace one component isn't great.

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Hm, the Sempus are known to be quite fragile. Have you ever tested an E-Rider Sensor, you can get them at Grin, too, but of course it is much cheaper to order in China directly.
In my experience, the E-Rider Sensors are much more reliable than the Sempus.

NixyMouse said:

it might be feasible to use a power meter and have it stream data via ANT+ or BT to a microcontroller

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This fits perfectly to @casainhos latest project
But as far as I know, those power meters are much more expensive than an E-Rider bottom bracket sensor. This offer seems to be a china clone of the official Garmin product...


regards
stancecoke

Thank you so much for the links and information! I was tempted to try the E-Rider BB but wanted to explore other options before committing to another BB based solution. Plus, I was also thinking of installing an old Hollowtech II crankset I have laying in a parts bin (mostly interested to see if the sealed bearings hold up any better than the ones found in typical square tapper BB carts) which obviously wouldn't be possible with a E-Rider BB. Knowing they can be had straight from China for cheaper does make them a lot more attractive though.

I could be very wrong, because I veered off from Grin's products and went the mid-drive route, but I had, at one time, familiarized myself with the torque sensing options. I seem to remember Hollowtech II spindles as an option with at least one product in the Grin lineup and I doubt it was the Thorn or Sempu, so ... are you sure that E-Rider does not have an ISIS spline BB? Just for the lack of a need to drill the BB shell I am biased towards the E-Rider system. If it were me I'd look into the E-Rider system some more and call it good. A powermeter still locks you into some proprietary hardware and it is actually possible to overthink this stuff. On the power delivery side you want direct, no BS, connection with the power source. Drive by wire is for fighter planes and nuclear submarines. IMO.

Yeah there are ISIS spline BBs available but the problem is Hollowtech II cranks have the BB axle attached to the crank unlike the original Hollowtech cranks (I still have no clue why Shimano made them part of the same product series considering how different Hollowtech I and II are but that's a discussion for another thread). Either way, looking at it I think I'm going to order an E-Rider BB for testing and try to see if I can build a strain gauge system on the spare crank on the side. Out of curiosity, is there a guide somewhere about how to disassemble and service the E-Rider BBs?

Hello guys I'll try working on a bridge from ANT+ to analog output to inject in a controller.
What I'll use are:
- PowerSense from AVIO 149£
- Adafruit Feather nRF52840 Express 25$
- ant-arduino library
My goal is to get everything to work as both a cadence sensor and a torque sensor to inject the controls to a Nucular 24F controller.

jacopo said:

Hello guys I'll try working on a bridge from ANT+ to analog output to inject in a controller.
What I'll use are:
- PowerSense from AVIO 149£
- Adafruit Feather nRF52840 Express 25$
- ant-arduino library
My goal is to get everything to work as both a cadence sensor and a torque sensor to inject the controls to a Nucular 24F controller.

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Nice project!
Did you start already?
Can you have multiple simultaneous clients connected to the power meter so you can use the arduino along with a bicycle computer?