Mountain bikes and ten-speed bicycles operate on a similar shifting apparatus, although there are basic differences based on the specific uses of each type of bike. Mountain bikes travel on off-road trails, which influences their gear ratio designs, making them lower-geared to handle varying rough terrain. Ten-speed road bikes travel on the road, where higher speeds are common. Consequently, gear ratios must be higher to shift smoothly at faster speeds.
Mountain bikes run one, two, or most commonly, three front chain rings. The smallest ring typically has 22 teeth, the middle ring has 32 teeth and the largest ring usually has 42 teeth. The sizes of the three chain rings create smooth shifting from ring to ring for riding on continually varying terrain.
Ten speeds are capable of running up to three chain front rings, although they often use two (referred to as a double). The large front chain ring commonly has 53 teeth and the smaller ring typically has 39 teeth, although both rings range in size by several teeth. Shifting between front chain rings is not as smooth as mountain bikes, due to the large disparity between the two sizes of front chain rings.
The most common rear cassette on a mountain bike has nine rear sprockets, which range in size by teeth. The smallest rear sprockets have 11 or 12 teeth, and the largest have 28 to 34 teeth. The wide range of rear sprockets affords you a larger variety of gear ratios when traveling.
Cassettes on ten speeds have ten rear sprockets. The smallest sprocket has 11 teeth and the largest sprocket ranges from 23 teeth to 28 teeth. Road bike cassettes are more compact in size because their sprockets have less variation in size when compared to those of mountain bikes.
Gear ratios of mountain bikes operate best at lower speeds than ten speed bikes, because the front rings have fewer teeth. The overall gear ratio of a mountain bike provides you with smoother riding experience on varying low speed terrain, such as trails.
The larger range of gear ratios on ten speed bicycles delivers the widest gear range of the two bike styles. Front chain rings on ten speed bicycles are larger, although the rear cassettes have less variation in sprocket sizes to assist with smooth shifting at higher speeds.