Revel Propulsion, a company in OR, has a DIY mid-drive with a bottom bracket incorporating a torque sensor. I procured a kit and it is designed and executed masterfully. The motor/controller, display and all mounting hardware weigh slightly less than eight pounds and will replace the bottom bracket and crankset which weigh slightly more than two pounds. The battery and "cradle" which mount on the downtube weigh slightly more than four pounds providing a net addition of about 10 pounds. The torque is reported as slightly greater than 60nm making it in line if slightly less than many mid-drives, but this kit has been designed for individuals who like to pedal. I am not affiliated with the company in any way, and will report on the kit at some future time when several other projects are completed.

Doesn't appear as though this thread was very "attractive", but I completed the easy and well instructed (manual and nine utube videos) addition yesterday. The bike plus complete system weighs just under 36 pounds; bike handles nicely with the low-center weight addition; seat of the pants performance puts it squarely in line with Bosch and Yamaha OEM bikes that I've ridden. I'll post pictures in a couple of days.

These are the only pictures that I have.

Hard for me to imagine, but qualitatively the Revel kit produces power more smoothly than Yamaha or Bosch systems I've tested or own. Amazing accomplishment for a small company. Also the assist goes from Class1 (20 mph) to Class 3 (28 mph) just by pushing a button on the display.

Interesting. That looks to be the type of system I'd like to replace my Hilltopper front wheel hub.

Much as I like the Hilltopper for its throttle, the "all or nothing" power is not particularly encouraging to pedaling. It actually is harder to pedal when the surge is too committed to achieving 23mph whether you want to or not. Unless one feathers the throttle button constantly to just provide small bursts of power, you end up riding the bike as if it's a mini motorcycle.

My new Giant LaFree E+1 has a Yahama motor, and it is very smooth.

Can I ask what you paid for this system? (I did check out their <very poorly designed> website, and didn't find a price anywhere)

I'm surprised you didn't see it unless they took it down recently. It's $1225 for the complete system.

Nice that the motor works with a bottom bracket torque pedal assist sensor, I’ve only previously seen the Grin Tech combination of BB sensor + hub motor, great this is now available on a kit mid-drive motor.