I commute from approximately where 28 and 29 cross over (centreville) to my work in Herndon. Right now when I drive I take 28 to Westfields Blvd which turns into Centreville Rd, then Frying Pan Rd to Monroe St and from here on it would be very bicycle friendly. My biggest snag is trying to get from my apartment to Centreville Rd because between the two are some very hairy spots for cyclists - ones I will not even consider trying, especially going in to winter when we have much less sunlight.

I wish 7100 had bike paths all the way out to my area but I think those only start where 7100 and 50 meet.