The Journey Planner system, one of the two key features of CycleStreets, will plan routes for you automatically based on the route network known to it.
A proposed new feature (not yet available) is the ability to draw (or upload GPS traces of) your own routes that you already know about.
Sadly, we missed getting this ready in time for the first release of the CycleStreets website. Do you have funding that would help us add this feature, or which would help us set up a collaboration with existing websites that do this?
Here are some route websites that may be of interest: