Originally Posted by
hr2510
Thanks. I did find a spot with a 12 degree 20w MR16 bulb. It's smaller than the other although I'm not too concerned about adding a pound or two extra to a 60 pound tandem.
This one has a o-ring seal and looks easy enough to adapt/mount and to drill and add a switch.It's about $3 cheaper also.
I made my bike light from this. I replaced the stock 20W flood with a 20W spot, fabricated a mounting/adjusting system, wiring, switch, connectors, etc. I use a 3.6 Watt-hour SLA battery I carry in my rear rack trunk, set up to plug into the charger in the garage.
A tip if you use this light. The halogen lamp is not firmly mounted so it will bounce around within the light enclosure. I ended up switching the position of the O-ring and the lens, and putting a few drops of silicone at the edge of the halogen lamp to stabilize it against the lens.
It works great. I use it mainly for early morning fitness rides. Plenty of light, and I think the battery will last about an hour. I've never run it down as my morning rides are around 25 minutes.
Between Home Depot, Radio Shack and zbattery.com, I think I spent about $65 on it, and it's equivalent to a commercial light that costs twice that or more. But, like you, I like to tinker. The return on my time was probably about $2/hour, but I'm OK with that. It was a fun project, and quite successful.