Gear Inch Calculator

Enter the number of teeth on the front ring, rear cog, and the diameter of the wheel into the calculator to determine the gear inch.

Gear Inch Formula

The following is the gear inch formula:

GI = TFR / TRC * D

  • Where GI is the gear inch
  • TFR is the number of teeth in the front ring
  • TRC is the number of teeth in the rear cog
  • D is the diameter of the wheels (inches)

Gear Inch Definition

A gear inch is defined as the ratio of the teeth in the front ring divided by the rear cog times the diameter of the wheel.

What do gear inches mean?

Gear inches are a way of describing the mechanical advantage of different gear settings on a bike. The higher the gear inch the greater the mechanical advantage provided from the petals to the wheels.

How do gear inches work?

Gear inches work by the difference in teeth of two different cogs in a bike system. The greater the different between the two cogs the greater the gear inch and the more advantage gained by the biker.

What is a good gear inch?

A good gear inch depends on the biking conditions. For down hill conditions you may want a lower gear inch so that you can petal a optimal speed, and vise verse for climbing a hill.

How to calculate gear inches?

  1. First, determine the number of teeth in the front cog. Measure or count the total number of teeth in the front cog. For this example, we will say this is 10.
  2. Next, determine the number of teeth in the rear cog. For this example we will say this is 5.
  3. Next, determine the diameter of the wheel. We will assume a 35″ tire.
  4. Finally, calculate the number of gear inches using the formula above. So, (10/5)*35 = 70 gear inches.
gear inch calculator
gear inch formula