It's possible to measure power with accelerometers.

 VELOCITY=3DMPH x 5280/3600

 FORCE=3DMASS x (ACCEL+DECEL)     ;  ACCEL & DECEL in < g >

 HP=3DFORCE x VELOCITY/550

DECEL subsumes grade, aero drag, & so on. In principle, a 3-axis
accelerometer & sufficiently whiz-bang DSP could be carried loose
in your pocket.

Measuring torque at the hub is much simpler...
--=20
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