On a recent weekend -- when the humidity was low and the weather was GORGEOUS -- Bob and I made a trip on bicycles to Great Falls and back to Arlington.
At the entrance gate to the Great Falls park, all vehicles pay an entrance fee. Cars pay $5 each, while each bicycle pays $3. So Bob and I paid $6, but if we had driven there in a car, it would have been a dollar less. If we'd been a family of four? Fuhgeddaboutit.
By the way, riding in the park was very nice -- lots of trails, though some were pretty rough from Hurricane Hanna rains, and all wonderfully shaded. Peaceful and quiet.
(Note to self: pay attention next time and be sure to read the part in the bicycle tour guidebook that says "hilly.")