Bike Gear Calculator
Gear ratios, gear inches, rollout and speed at cadence for every gear.
About this tool
Enter your chainring and cassette tooth counts, choose a wheel size and tyre width, and set your cadence. The table shows every combination as speed in km/h or mph, gear inches, development in metres or gear ratio, plus the overall gear range and the wheel's estimated diameter and circumference.
How bike gearing is calculated
A gear ratio is the chainring's teeth divided by the rear cog's teeth. A 50-tooth ring with an 11-tooth cog is 4.55, so the back wheel turns 4.55 times for every turn of the pedals. Gear inches multiply the ratio by the wheel diameter in inches, a convention from the penny-farthing era that lets you compare gears across different wheel sizes. Development, also called rollout or metres of development, is the distance the bike travels per pedal revolution: the ratio times the wheel's circumference. Speed is development ร cadence. On a 700c wheel with 28 mm tyres, about 678 mm across, 50 ร 11 gives about 121 gear inches and 9.7 m per pedal stroke, which is about 52 km/h at 90 rpm. A 34 ร 28 climbing gear gives about 32 gear inches and 14 km/h at the same cadence. The range figure, highest ratio รท lowest, shows how wide the gearing is; a 50/34 with 11โ28 cassette gives about 374%. Honest limits: the diameter is estimated from the ETRTO rim size plus twice the tyre width, so measured rollout can differ by a percent or two, and speed ignores wind, gradient and drivetrain friction. The speed, distance and time calculator and the pace calculator plan rides and runs.
Frequently asked questions
What is a good gear ratio for climbing?
A 1:1 ratio or lower, such as 34 ร 34, makes steep climbs easier; gravel and mountain bikes go lower still.
What are gear inches?
The gear ratio multiplied by the wheel diameter in inches; a higher number means a harder, faster gear.
How fast can I go in my top gear?
Multiply development by cadence: 50 ร 11 on a 700 ร 28c wheel at 90 rpm is about 52 km/h.
Is my data saved?
No. The calculation runs in your browser and nothing is stored or sent.