Thanks for all the replies.
I have no idea how various “smart” trainers work or don’t with backpedalling. I use a dumb trainer so I am still confused.
Nothing happens when I back pedal. The forward momentum of the wheel continues going forwards and slowly comes to a stop after about 15 seconds when I back pedal. The power on the screen reduces slowly down to zero over this 15 seconds or so until the wheel finally comes to a stop, caused by the friction of the wheel-on roller of the dumb trainer.
So backpedalling for me does nothing.
Would it be different if I fitted a cadence sensor onto the pedal?
I use a garmin speed and cadence sensor attached to the rear wheel chain stays in the usual manner, but haven’t attached a cadence sensor to the pedal.
I have a spare cadence sensor but havn’t bothered attaching it to the indoor bike i use.
Will this recognise backpedalling? Or is it for “smart” trainers only?