As much as I hate to feel like I'm missing out on the NYC bike events, I think I'm going to skip this one. Last year I:

--waited for over 90 minutes for the ride to start. And I got there pretty early.
--basically walked the bike to Central Park
--waited another 90 minutes to get on the SI ferry at the end

Some parts of it were fun, like crossing the Verazzano, but overall it wasn't worth the agonizing time spent waiting and the frustratingly slow pace. I would only do this ride if you're new to cycling and/or you're doing it with family/friends.

As for the original question, I did it with a road bike, no problem.