I agree, something A-bike-ish shouldn't be a problem. I bring my Razor A5 scooter (adult size, 8" wheels) on our buses all the time, and no one has complained. Of course it all depends on how crowded the bus is. If half the seats are empty you could probably bring a bike like my Swift on. If, OTOH, it's like some of our buses at rush hour where you have 20 people standing in the aisle, no one is going to be happy about sharing space with that lumpy, pointy thing.