I've done it several times, onces on an old mountain bike, once on a rented road bike, once on a borrowed road bike. The first few hours are slow--lots of stop and go in Brooklyn--and the last twenty are the hilliest, as I said, in the Bronx. There are lots of stops and this is lots of food and overall it is great fun. And by the way, for those who aren't sure about a century, there are clearly marked ways to do fewer miles. There are people out there on every kind of bicycle. See you there.