Ride starts at the Dana Discovery Center at the north end of Central Park, on W. 110th St. between Malcolm X Blvd. (Sixth Ave.) and Fifth Ave. Bathrooms have outside access on the north side of the building and are generally open by 8:00 a.m. You can get there via the C train to 110th St. or the 2/3 train to Central Park North.
The route is almost entirely on bike lanes and bike paths. You start with urban riding up St. Nicholas Ave. (watch for glass); then take a wooded bike path and cross the newly restored High Bridge (stop for a photo op). Then it's more urban riding up University Ave. Work your way over to Van Cortlandt Park South. Turn onto Broadway, make a pit stop at the Van Cortlandt Park restrooms, then continue up Broadway 3/10th mile to Lloyd's Carrot Cake for the best in NYC (either with nuts & raisins or without), or one of their other famous cakes. (Lloyd's is a very small storefront on the left, with a very small carrot sign - don't miss it.) If you want something more substantial there's a deli in the same block. Cross Broadway (carefully) to the park side and watch a game of cricket while you snack.
The return route is over the Broadway Bridge and then down the Hudson Greenway to 72nd St.