Hybrid Bikes: they are a good compromise between performance, comfort and sturdiness. Good for the city and bike touring, rather light weight and narrow tires, many gears to go anywhere.
21 speed: perfect to go everywhere including going up very steep hills. There are 3 front chain rings and 7 rear gears. - Derailleur: Shimano Tourney SIS
Tires 700 x 35c: medium width tires with small thread, for comfort on asphalt and occasional off-road.