I'm up at 3am every Thursday in downtown manhattan, out the door at 3am, keep my heart rate close to 85% for most of the ride to Coney and back about 26 miles. Manhattan Bridge through Dumbo, Red Hook, under the BQE to Bay Ridge Road, to 96th over to Coney, then Ocean Parkway back, Prospect Park, Flushing Traffic Sewer back to Manhattan Bridge. Sure, it's dark, but very light traffic, well lit, and large stretches where I can open up and either hit all the green lights or blow the red lights with a little close attention.