LIE to exit 70 and head south, aprox. 1.8 miles.
Go past the 7/11, pass new Fire House on right corner & Hotwater St. on right, make the next Left, it comes fast so be in the Left lane.
After turn, you will see the sign for Manorville Hills County Park, take the gravel road to the gravel parking lot.
If you miss this turn, take any of the next turns and get to the north bound side of 111.
Once you are in the gravel parking lot, you will see a sign for the hiking trail head, diagonally across from that you will see a blue blaze on a skinny tree near a small dirt mound, for the mountain bike trail.

Google:
https://www.google.com/maps/dir//Manorville+Hills+County+Park+Parking+Lot,+40%C2%B051'50.+W,+7246+3rd+St+NE,+Manorville,+NY+11949/@40.8639597,-72.8034863,13685m/data=!3m1!1e3!4m9!4m8!1m0!1m5!1m1!1s0x89e85edb2a288377:0x539987ba95be8b89!2m2!1d-72.768467!2d40.863965!3e0?hl=en