I had the opportunity of riding the Birdy City for a day and not sure whether to get the Touring or the World (Comfort).

I have the following questions:
  • The World is cheaper but seems to use an older frame. Anybody knows if that makes a difference?
  • After a whole day riding, my back was fine but my butt wasn't, as the original saddle is not comfy enough. Is there an alternative?
  • Are there additional recommended equipments besides mudguards and a rear rack? The rear rack can take up to 15kg/33lbs but I don't intend to bring that much anyway.

Thank you.