Well, that happens to be my dilemma, i only own a flip flop track bike, and im not sure i would want to ride that the full 145 miles either despite the acclaimed flat course. It seems like a better idea just to rent a geared road bike, since i don't own one myself. Anyways, my decision is not yet written in stone, so i could still go either way, but can ask why would not recommend renting for a century? My plan was to rent the bike for 24 hrs at the bike shop the day before, and dial it in on my ride back home to brooklyn and further tune it at prospect park throughout the night. Then wake up, and ride into manhattan, make my last adjustments, and stick it out for century ride, aftwerwards drive back to NYC, and return the bike within 24 hrs. I feel its a good alternative considering my choices, i really wanna ride this event, so i ask, how bad can it really be?