Los Angeles has actually already got a bicycle route planner - one of the first that I know of to be developed. I haven't visited the site for awhile, but it seemed pretty functional last time I looked at it:
http://www.bikemetro.com/route/routehome.aspThis was developed by a consultant, GeoPerception, and they were looking to market it to other locations, but to my knowledge, nobody bought it. It was kind of expensive, and, like Bycycle itself, very data driven. To make it work, you gotta have good underlying data.
Mark