Bikehike should work. You have to click on "Options" then set the routing algorithm to OpenStreetMap, and set the travel mode to cycling. Then it should route along cyclepaths.
Or Bike Route Toaster can do a similar thing.
Both of these use Cloudmade routing.
Or you could try Cyclestreets. It can give interesting routes for cycling, including quietest or fastest options.
http://www.cyclestreets.net/