I've only done one century so far, so by definition it was on the wrongest bike. I passed and was passed by a lot of people and I believe mine was the only one I saw that was more than 20 years old (mine was a little over 40 yo at the time) and I was definitely the only one on the course with a full set of fenders, a rear rack, and a pannier. I got a lot of perplexed looks (and a couple compliments) at the rest stops.

But it's a bike designed for long days in the saddle. I finished tired but comfortable, and in style, so it was also the rightest bike.