I used bike-hooks from Home Depot, the medium-sized yellow ones, NOT the giant 6" crawford hooks, which are too large, and I alternate the road bikes front-wheel up, back-wheel up, etc.:
http://www.amazon.com/
Most of my handlebars are 38cm. I placed the hooks 11" apart, even though in theory you can place them as close as 9" apart. I screwed them into a 2x6" and slightly offset the hooks so every other hook is about 3" higher than the other.
This allows me to put up to 13 bikes in a 12"x2"x6" plank, on a wall, with about 3.5' projection into the room. The hooks must be wider for mountain bike storage as the mountain bikes are much wider in the handlebar area. By hanging it from one dropout, and placing the fork in the seat tube (a trick i saw at brian baylis's house), you can also mount 2 frames per hook using this system.
- Don Gillies
San Diego, CA, USA