This is something I've been wondering about, except the other way around. In my mind what makes a bike a commuter is that it has a rack and fenders and slightly wider tires. So my question is would such a bike be acceptable to bring to group rides or do centuries? Currently I only have a mountain bike, but I want to get a road bike, actually probably a touring or cyclocross bike for added durability, and equip it for commuting. But if I want to go on group rides do I really need to start thinking about n+2 right now? Or should I take the rack and fenders off and switch to skinnier tires for road riding? Or should I just leave them on and show up for group rides as is?

Does anyone else ride group rides with their commuting bike?