Bright Luxeon LED Bike Light

Step 4 Key components: Durable housing and heat sink

This is the key element for the whole DIY bike light. Luxeon LEDs, especially 3W and higher, require supplemental heat dissipation. Without proper conductance of heat away from the diode, it will overheat and fail. At the very least, the LED will operate with reduced efficiency. It just so happens that a Luxeon Star LED fits conveniently inside a 3/4" copper plumbing cap. It's quite possible that the cap alone will provide enough heat dissipation for 1W Luxeons. For 3W and above the additional aluminum heat sink can only help.