If you don't mind a couple miles out, Sterling,Va has some pretty good pave trails. They are technically mup but not heavily used and not the least bit flat(some rises need standing and working at it). My fav and old neighborhood was Sugarland-Run (Google Sugarland run dr. Sterling) If done properly there is enough to link the 4 neghborhoods together to make up over 10 miles of trails in many configurations.