Kevin writes -
This page describes the construction of a bike light comprising three 3W Luxeon LEDs. This project had three main goals. 1.) Make a light suitable for use in 24-hour mountain bike racing. 2.) Use readily available material as much as possible. 3.) Offer the details to the community and invite any and all comments.
Race Day Nutrition – Link.
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Editor at large - Make magazine. Creative director - Adafruit Industries, contributing editor - Popular Science. Previously: Founded - Hack-a-Day, how-to editor - Engadget, Director of product development - Fallon Worldwide, Technology Director - Braincraft.
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Kind of expensive, I’d try to make one cheaper, but a good resource.