<Dd> the number of usable gear ratios is 22; </Dd> <Dd> the number of distinct gear ratios is typically 16 to 18 . </Dd> <P> The combination of 3 chainrings and an 8 - sprocket cogset does not result in 24 usable gear ratios . Instead it provides 3 overlapping ranges of 7, 8, and 7 gear ratios . The outer ranges only have 7 ratios rather than 8 because the extreme combinations (largest chainring to largest rear sprocket, smallest chainring to smallest rear sprocket) result in a very diagonal chain alignment which is inefficient and causes excessive chain wear . Due to the overlap, there will usually be some duplicates or near - duplicates, so that there might only be 16 or 18 distinct gear ratios . It may not be feasible to use these distinct ratios in strict low - high sequence anyway due to the complicated shifting patterns involved (e.g. simultaneous double or triple shift on the rear derailleur and a single shift on the front derailleur). In the worst case there could be only 10 distinct gear ratios, if the percentage step between chainrings is the same as the percentage step between sprockets . However, if the most popular ratio is duplicated then it may be feasible to extend the life of the gear set by using different versions of this popular ratio . </P> <P> The gearing range indicates the difference between bottom gear and top gear, and provides some measure of the range of conditions (high speed versus steep hills) with which the gears can cope; the strength, experience, and fitness level of the cyclist are also significant . A range of 300% or 3: 1 means that for the same pedalling speed a cyclist could travel 3 times as fast in top gear as in bottom gear (assuming sufficient strength, etc .). Conversely, for the same pedalling effort, a cyclist could climb a much steeper hill in bottom gear than in top gear . </P>

What are the different speeds on a bike