Bicycle Gear Ratio & Speed Calculator
Enter your chainring and cassette teeth counts, pick your wheel size, and drag the cadence slider to see your speed for every gear combination - sorted slowest to fastest. Nothing uploaded.
Chainrings
Cadence
Speed unit
Learn more: gear ratios, cadence, and drivetrain planning
Understanding gear ratio and the chainring-to-sprocket relationship
Gear ratio is how many times the rear wheel turns per pedal stroke. Calculate it by dividing the chainring teeth by the rear sprocket teeth. For example, a 50-tooth chainring with an 11-tooth sprocket gives 50 / 11 = 4.55 ratio, meaning the wheel turns 4.55 revolutions per pedal. Higher ratios are harder to pedal but faster on flat terrain. Lower ratios are easier to pedal but slower - essential for climbing steep grades. Road bikes typically have ratios from 2.8 (bailout gear) to 5.5 (top sprinting gear).
How cadence affects your speed
Cadence is how fast you pedal, measured in revolutions per minute (rpm). Most cyclists cruise at 80-100 rpm. The equation is: Speed = Gear Ratio x Wheel Circumference x Cadence. With a 700c wheel (2105 mm circumference), a 3.0 ratio, and 90 rpm cadence: 3.0 x 2.105m x 90 x 60 = about 34 km/h. Increasing cadence by 10 rpm increases speed by about 3.8 km/h in that gear. The calculator shows how speed changes as you drag the cadence slider, so you can see what speeds are realistic for your pedaling style.
Gear range and drivetrain choice for climbing vs flat terrain
Gear range (top speed divided by lowest speed at the same cadence) determines how many different speeds you can access. A range of 4x to 5x is typical for road bikes. For hilly terrain, a wider range is better. A compact double (50/34 chainrings) with an 11-34 cassette gives a range of about 4.5x and a very low bailout gear for steep climbs. A standard double (53/39) with 11-28 gives only 3.8x, making climbing harder on steep grades. Mountain bikes and gravel bikes often use 1x drivetrains (single chainring) with wide cassettes (11-52) for maximum range despite more chain drops between gears.
Wheel size effect on speed and cadence
Larger wheels have bigger circumferences, so they cover more ground per rotation. A 700c road wheel (2105 mm) is much larger than a 26-inch mountain bike wheel (1620 mm). At the same gear ratio and cadence, the 700c wheel goes faster. The calculator handles all common sizes: 700c, 650c, 29er (760 mm), 27.5", and 26". Choose your exact wheel size including tire width if you know it, since tire diameter affects speed by 1-2 km/h.
FAQ
What is gear ratio on a bicycle?
Gear ratio is the number of rear wheel revolutions per pedal stroke. It is calculated by dividing the chainring teeth count by the rear sprocket teeth count. A 50-tooth chainring with an 11-tooth sprocket gives a ratio of 4.5 - meaning the wheel turns 4.5 times per pedal stroke.
How do I calculate my bike speed from cadence?
Speed = gear ratio x wheel circumference x cadence. For example, with a gear ratio of 3.0, a 700c wheel (2105mm circumference), and a cadence of 90rpm: 3.0 x 2.105m x 90 x 60 = 34.1 km/h. The calculator does this for every gear combination simultaneously.
What is a good gear range ratio for a road bike?
Most road bikes have a gear range ratio (top speed / lowest speed at the same cadence) of around 4x to 5x. A wider range is better for hilly terrain. A compact double chainring (50/34) with an 11-28 cassette gives a range ratio of around 4.5x.