For the cranks we used a wheel with no holes or handles that jut out, as this would avoid safety concerns with people getting their hands caught or getting hit. We spray painted the crank boxes silver to stand out from the grey walls, but still matched the overall theme of our room.
The crank used a reed switch, which detected when the crank had made a full revolution. We used this to determine RPM, and whether the wheel was spinning or not. At a minimum speed, the green lights in the barrels turn off. After the wheel has stopped spinning for a few seconds, the barrel lights turn back on. Below is a schematic for our wiring for this system, as well as a picture of the inside of the crank, which includes the reed switch assembly.