Your height: 5'8" to 6'0" (172 to 183cm) approximatly (?).
Frame size = 21.75in/55cm
Comments:
Mountain Bikes: they are sturdy and designed to go everywhere including off-road. Good for rough riding. In general heavy and with deep thread tires slow on paved roads. Not good city bikes unless narrower and slick tires are installed.
18 speed: perfect to go everywhere including going up very steep hills. There are 3 front chain rings and 6 rear gears. - Derailleur: Shimano Tourney
Tires 26 x 1.95: wide tires, deep thread, all terrain.