Everyone is running a RFID chip, why not space 2 sets of RFID mats spread 20-30m away from each other. If your distance to the person in front of you doesn't change appreciably between the 2 sets of mats than you aren't passing, you are drafting...
-Placing the mats in "sets" allows you to calculate both the relative and absolute speeds of the riders.
-Placing the mats in "sets" allows you to calculate both the relative and absolute speeds of the riders.