I have a livestrong spinning bike at work that has a built-in speed sensor with Ant+ that connects to my Garmin 235 watch, it measure speed and distance, it works great.
At home, i have Star trac spinning bike purchase in my local gym when they renew their equipment.
Im looking for a Ant+ speed sensor like the one in the picture below, my whell is not metal but plastic, but the magnet can be attached with some glue.
Ps: i just want to measure the speed and distance with Garmin 235 while doing exercise.