Still don’t own a bike? You can borrow one for free from now through the end of September. Sign up at downtownny.com for a complimentary two-and-a-half-hour spin on one of 30 hybrids and mountain bikes, which you can pick up at South Street Seaport (you’ll need a credit card as a guarantee). Pedal around the tip of lower Manhattan and then up the West Side Highway to the newly opened Pier 64 to luxuriate on some remarkably cushy grass. Break for a meal at the new Water Taxi beach on the north side of Pier 17. The beach’s fish shack and bar open Memorial Day weekend; mini golf and table tennis will follow in early June.