Long IR. No one is using that for AVs. (that might change after this incident!)
This is Arizona, however. The nights do cool down, but the concrete will still store a lot to heat.
Regardless, a human and metal bike should be very easily discernible with FLIR of adequate resolution.
A garden-variety uncooled LWIR camera from FLIR can see a difference of 0.05 degree. As long as the pedestrian isn’t wearing a thermal blanket from head to toe he/she can be seen.