I always love it when someone turns this into a "straight edge", organic only, single speed dude vs. roadie snob thing.

On the group rides I go to, of which there are three, there are widely ranging levels of bikes and ability levels. $10k to 1980's 10 speeds. Only thing that matters is that you go fast, and keep it rubber side down.

Oh, and your friend would have to be turning 140rpm to avoid getting dropped for most of a group ride around here, FYI.