man I picked up one of those cheap niterider cadence sensors because I read some people got them to work with garmin 500s. after toying with it for 30 minutes I gave up and cut the zip ties (can we figure out a better way to mount these on bikes PLEASE) I gave up because I'm on my way out the door. as I cut the last one, it comes on lol. Good news is I found a $5 cadence sensor, now I just gotta go rebuy some zip ties