This just seems way better and more likely to be solved with lidar, or a similar passive solution, rather than relying on your bike to broadcast "this guy is mo

This just seems way better and more likely to be solved with lidar, or a similar passive solution, rather than relying on your bike to broadcast "this guy is more vulnerable/faster/more litigious than you expect, so be really sure not to clip him". Even if the network was there, it's a difficult physical/technological problem to figure out everyone's relative position and velocity to suitable precision with something like GPS, or GPS + accelerometers. But mostly solved with lidar.