Here's the trip report on EveryTrail. 10.0 miles. 1.25 hours.
I rode up 8th Ave, cross town on 20th, joined the East River bike trail at Stuyvesant Point, went under the Williamsburg, Manhattan and Brooklyn Bridges, South Street Seaport, round the Battery, up the Hudson and across the Village.
The pedestrians are the worst in Battery Park City, sometimes blocking the whole super-wide path with dogs and baby carriages, not moving. The best bike trail is just north of there, betw the top of Battery Park and 46th St. It's a straight shoot the whole way.
Today the leg pain and tiredness are gone, endorphins flowing make me happy!