There is a whole thread about "Century Bikes".

http://www.bikeforums.net/long-dista...bicycle-s.html

I'll have to update it soon, as I just hit another Century ride on a different bike

What is pretty obvious about browsing the thread is that there is no single style of century bike. Oddly enough, not everyone is riding a Roubaix.

There are a few Hybrids, MTBs, Fat bikes, and Flat bar bikes mixed in.

For the OP, it is probably not your Trek XO that is holding you back from completing a Century ride. You really just need to do time on the bike. Whatever bike you use. Do some 50 mile rides. 60 mile rides... etc. Then the Century ride will be just another ride

Of the bikes I'm currently riding, I think the only one I haven't done a century ride on is my cargo bike, and that has done at least a half century ride.

Perhaps the most important thing about bike choice is reliability. You need a bike to get you to the end. Even so, a well prepared rider should be able to deal with different issues that crop up. Most of my century rides are solo rides, and on my last two trips (4 century+ rides), I've broken one spoke and had a blowout (with tire damage). The issues slowed me down, but weren't enough to stop me.