Right next to king kullen
Jericho tpk and stop n shop, just west of Woodbury rd is the main trailhead on the north end. The northern most trailhead is at cold spring harbour, BillyJoel park, tho your are not permitted to mtb the trail, it is the best on LIsland to replicate real mountain biking with technical climbs and switch backs, gnarly singletrack. Good stuff if you can get away with it. Did I just implicate meself?...
There is also one just north of Plainview Road. Or U can park on the street just north of Haypath
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