Cycling Gear Inches Calculator
Choose your tyre size, then enter your chainring and sprocket teeth. You get a table of gear inches, development in metres and speed for every gear.
Worked examples
The highest gear on a road bike
700 x 25c, 50 teeth front, 11 teeth rear
119.9 gear inches, 9.57 m per pedal turn
At 90 turns a minute that is about 51.7 km/h.
The lowest gear
700 x 25c, 34 teeth front, 28 teeth rear
32.0 gear inches
A gear for steep climbs.
About Cycling Gear Inches Calculator
Gear inches is a long established way to compare the gearing of bicycles. It is the diameter of the driven wheel in inches, multiplied by the number of teeth on the chainring and divided by the number on the rear sprocket. A bigger figure means a harder gear that takes you further with each turn of the pedals, and a small figure means an easy gear for climbing. It lets you compare bikes with different wheels and cassettes fairly.
This calculator builds a table of every gear on your bike from the chainring and sprocket sizes you enter. It also shows the development, which is the distance travelled in metres for each pedal turn, and the speed at the cadence you choose. Pick your tyre size from the list or enter your own roll-out. The range from the lowest to the highest gear tells you how wide your gearing is.
How to use Cycling Gear Inches Calculator
- Choose your tyre size, or enter your own roll-out in millimetres.
- Type your chainring sizes and your sprocket sizes, separated by commas.
- Set the cadence in turns a minute that you pedal at.
- Read the gear inches table, the metres per pedal turn and the speed for each gear.
Common uses
- Choosing a cassette for hilly rides
- Comparing a road bike with a hybrid or a touring bike
- Working out the top speed of a fixed gear
- Deciding between a compact and standard chainset
Frequently asked questions
How are gear inches calculated?
Wheel diameter in inches, multiplied by the chainring teeth and divided by the sprocket teeth. A 27 inch wheel with 42 teeth at the front and 17 at the back is 66.7 gear inches.
What is development?
The distance the bike travels for one full turn of the cranks, in metres. It is the roll-out multiplied by the chainring and divided by the sprocket. It gives the same ranking as gear inches in more modern units.
What cadence should I use?
Many riders settle between 80 and 100 turns a minute on the road. Use your own average to find the speeds you reach in each gear.
How do I measure my roll-out?
Put a mark on the tyre and on the floor, roll the bike forwards in a straight line for one complete turn of the wheel with you on it, and measure the distance in millimetres.
What are typical gear inches for a road bike?
A 700 x 25c wheel with a 50 tooth chainring and an 11 tooth sprocket is about 119.9 gear inches. A 34 tooth ring with a 28 tooth sprocket is about 32.0.