| The effect |
| Introduction: What are gear inches? |
Gear inch is an archaic measurement that dates back to the days of
the high wheel bicycle. It was designed to measure the high wheel diameter
needed in order to travel a given distance with one revolution of the
cranks. In Europe, it is common to give the development (=distance in meters) which is traveled by one revolution of the crank. In the diagrams below, you find both meters and gear inches. |
 Gear range: 307% |
3-speed hub + speed-drive The blue bars show the development
(in meters) resp. the inch gears of a 3-speed bike. The red bars show the additional 3 speeds, if speed-drive is engaged. A gear range of 307%. (Example: 27 tooth chainring, 18 tooth rear cog, 700C rear wheel) |
 Gear range: 370% |
5-speed hub + speed-drive
The blue bars show the development (in meters) resp. the inch gears of a 5-speed bike. The red bars show the additional 5 speeds, if speed-drive is engaged. A gear range of 370%. (Example: 27 tooth chainring, 18 tooth rear cog, 700C rear wheel) |
 Gear range : 403% |
7-speed hub SRAM Spectro 7 + speed-drive
The blue bars show the development (in meters) resp. the inch gears of a 7-speed bike, equipped with SRAM Spectro 7-speed rear hub. The red bars show the additional 7speeds, if speed-drive is engaged. A gear range of 504%. (Example: 36 tooth chainring, 18 tooth rear cog, 700C rear wheel) |
 Gear range: 486% |
Comparison: 24 speed derailleur system.
(Example: triple chainrings 42/32/22, cassette 28/24/21/18/16/14/12/11, rear wheel 26") Several gears (see black columns) are provided in two- or threefold. |