Gear ratio tells how many times the rear wheel rotates for each full crank revolution. Multiplying that ratio by the rolling wheel diameter in inches yields gear inches, a common way to compare drivetrains. With cadence and wheel circumference, the calculator estimates how fast you would travel on smooth, level ground before real-world losses.

Tips

• Measure or look up tire ETRTO rolling diameter when possible.
• For multi-speed cassettes, run the calculator per cog you care about.
• Use cadence you can sustain on flat terrain for realistic pacing estimates.

Sources & References