I ride at the Lexus Velodrome in Detroit, it's an indoor facility and hosts frequent races throughout the year. I know they are looking for a way to track racers and display the information on a leader board. I was thinking about something like grouptrack but the update rate needs to be high (riders could make several laps between the current Grouptrack updates!) and GPS location isn't precise enough to separate riders on a 1/10th of mile track anyway. A typical Scratch race or Elimination race really isn't that hard to watch and know who's in front. But when a Madison race is going on and there are up to six teams with riders swapping in and out..... it can get confusing for the spectators very quickly (especially since there's a bar in the infield ;-) .
I've wondered if data could be collected directly from the ANT+ wheel speed sensors, but ANT+ repeaters would probably be necessary to cover reception around the entire track (I understand that this kind of thing is done in spin classes, but everybody is clustered stationary in the middle of the room so only one ANT+ repeater is required). Could Bluetooth or WiFi from a cycling computer be used without repeaters? Perhaps but what is the current data update rate from the bike computer? It might require a special operating mode from the bike computer that only collects and transmits wheel speed sensor information at a high enough rate and ignores all other functions that might be scheduled by the tiny OS within it.
I know they tried RFID tags, but the bikes cross in and out of the antenna field before the tag can get precharged and replies. I suggested an vision system using AprilTags (google it) but having cameras covering the entire track starts to get complex and expensive.
So, any creative people out there with an idea for cheap solution?