Bike Think - Gary Houchin-Miller shares his thoughts on technical topics which examine the fundamentals of bicycle performance. Links to lots of additional information as well. - http://www.bikethink.com/
Thankstomycranks cycling pages - Discussion of bicycle crank length, pedalling technique, chainring shapes and position on the bike with many references to scientific studies. - http://www.cranklength.info/
Analytic Cycling - Provides technical methods for evaluating and estimating cycling performance and parameters. - http://www.analyticcycling.com/
Science of Cycling - The Exploratorium in San Francisco answers questions about cycling. - http://www.exploratorium.edu/cycling/