In my city the buses do have bike racks, and people use them pretty frequently for road / town bikes. A cross country or downhill bike doesn't fit on the rack

In my city the buses do have bike racks, and people use them pretty frequently for road / town bikes. A cross country or downhill bike doesn't fit on the rack though. Longer wheelbases, wider tires and wider handlebars make it very difficult or impossible to rack or bring inside (if the driver even allows it, usually not the case unless the bus is very empty). The trains here have front wheel hooks, dedicated spots and more space, which is better. The size of XC and DH bikes still makes it a hassle though, and obviously you're limited to spots near the train stops.