there is a network off mtb trails at Heckscher and they are fair, but there are certainly better places to ride XC on the island. CLIMB had a night ride at Heckscher last year that was a lot of fun. And yea, the outer loop is great for road riding. Free parking during the week I believe and it's very low on traffic. Being right at the water, you get equal parts of head, tail, and crosswinds. It can get a bit monotonous though.