City Bikes: They are designed for comfort and daily commuting, to go to work, to school, to go shopping, etc.. Compromise between performance, comfort and sturdiness. Often loaded with useful accessories increasing the weight.
12 speed: good to go just about everywhere except very steep hills. The range of different ratios are more than enough for most people. There are 2 front chain rings and 6 rear gears. - Derailleur:
Tires 26 x 1.75: medium width tires with small thread, for comfort on asphalt and occasional off-road.