When I used to commute on my Brompton, I found that it was also a bit of a red rag to a bull. If I was behind someone on a road bike, and eventually got fed up with the speed, so decided to overtake, I'd often find that ten seconds later the road bike would hammer past me. Of course, on most occasions, twenty seconds after that he'd be exhausted and slow dramatically, at which point I'd go past again, and see the last of him (Note, the use of "he" and "him" was deliberate, I don't think I've ever had a woman do this sort of thing, it's always a bloke).