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Geek Bike Light Project

Click for full size image and detailRiding a bicycle in the desert sun is like working out in a blast furnace. Trail riding at night is a great alternative, but it's difficult to avoid obstacles like rocks, ravines and other cyclists in the dark.

One option is to strap a flashlight to your head. Another is to spend the $279 for a titanium / kryptonite headlight at the local bicycle specialty store. Or ...

Make your own Geek Bike Light from parts easily obtained at Home Depot, Radio Shack and the corner convenience store. In just a few hours, with minimal engineering skills and a twelve pack of your favorite adult beverage you'll be sporting a six pound bicycle lighting system that will outperform all others.

What You Will Need

1) Malibu yard light - with MR-11 or MR-16 bulb.
1) Rechargeable battery - 12 volt, 4 to 7 amp/hour.
1) Truck marker light - LED variety will extend battery life.
1) 3 foot section of aluminum channel - to make brackets.
1) Hose clamp - to secure the battery.

Miscellaneous - nuts and bolts, 2 conductor wire, electrical tape, connectors, cable ties, beer, mouse pad, bike.

Tools including beer, hacksaw, screwdrivers, file, drill, drill bits, wire strippers, diagonal cutters, beer.

Click for full size image and detailThe most important factor in deciding which light to use for the Geek Lite bicycle headlamp is the bulb. The yard lights have sockets which allow for substitution of bulbs with different parameters. MR-11 and MR-16 bulbs are available in various beamwidths and wattage ratings. Replacement bulbs are available in 10, 20, 35 and 50 watt varieties with beamwidths ranging from 12 to 40 degrees. A 20 watt narrow beam flood lamp is a good choice for brightness and battery life.

Geek Light Assembly

Click for full size image and detailOpen beer. Mount the headlight by removing one half of the included ground stake and replacing it with a 5 inch piece of aluminum channel. Fasten the channel to the bike using the front reflector harware. Attach the malibu spot to the other end of the channel with the hardware that comes with the light. This arrangement allows the headlight to move with the front fork as you steer the bicycle.

Attach the tail light using the rear reflector mounting hardware. Adjust the light so it will shine a few degrees up from horizontal. Open another beer.

Make a bracket for the battery with the channel aluminum. Use three pieces and bolt them together to form a "C" bracket that fits snuggly around the battery. Bolt the bracket to the bike frame using the water bottle mounting inserts. This step may require several beers.

Run wire along bicycle frame to headlight, tail light and battery. Use butt splices or twist and tape the light connections. Polarity is not important, but beer must have open end up to avoid spillage. Run wire for the battery inside the "C" bracket. Attach lugs to connect wire to the battery. Use cable ties to dress the wire to the bike frame.

Click for full size image and detailSecure the battery to the "C" bracket with the hose clamp. Secure and open yet another beer. Cut the mouse pad into strips and insert between battery and hose clamp to avoid damaging the battery.

Continue drinking beer until dark. Connect battery to turn on the geek light. Adjust headlight for best road illumination. If you have followed the instructions carefully it's probably not a good idea to attempt to ride bike at this time. Charge the battery by connecting to car battery or other 13.8 volt DC power source.

With a 20 watt bulb the Geek Light will run for about three hours between charges. A four amp/hour battery will yield over an hour of bright light and weighs less than three pounds. A power switch and charger posts have been added to our Geek Bike light for extra geekiness.

Geek Bike Light Project Photo Gallery

Technology Update - 2008

Years of real life road testing have proven the 35 watt medium beamwidth lamp to be the optimum choice for the original Geek Bike Light. Modern technology has created LEDs that are potential replacements for Malibu bulbs. I have begun experimenting with CREE diodes that are extremely bright. So far, the beamwidth has been a problem ( very narrow , but perhaps other have had better luck ). Let us all know if you have mastered this new science.

Share at Geek Lights or drop me a line on the KLorg message board.

On a related note I have confirmed that adult beverage and night riding are not compatible despite intense illumination and can validate my observation with six stiches in my knee.