Gear ratios, development & speed range from chainring and cog limits
| Gear | Ratio | Development | Speed @ 90 RPM |
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Founder & CEO, Toolraxy
Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.
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Type the tooth count of your smallest front chainring into the Min field.
Enter the tooth count of your largest chainring into the Max field, leave both identical if you run a single ring.
Set the smallest rear cog you own in the Cog Min box.
Fill in the largest cassette cog in the Cog Max box.
Measure your wheel diameter with the tire fitted and enter it in millimeters, or tap one of the preset buttons.
Choose a reference cadence that reflects how you actually ride.
Read the total gear range in the headline, then scan the tiles for lowest and highest ratio, development and speed.
Check the key gear table for the spread across climbing, cruising and sprinting combinations.
Gear range is the ratio of your hardest gear to your easiest gear, and it is the single number that tells you how versatile a drivetrain is. Everything else on this page is derived from two endpoints, the smallest chainring paired with the largest cog, and the largest chainring paired with the smallest cog.
Formula: Lowest ratio = smallest chainring ÷ largest cog Formula: Highest ratio = largest chainring ÷ smallest cog Formula: Development (m/rev) = ratio × wheel circumference Formula: Speed (km/h) = cadence × development × 60 ÷ 1000 Formula: Gear range = highest ratio ÷ lowest ratio
The tool normalizes whatever you enter. If you type 50 into the Min box and 34 into the Max box, it quietly reorders them, so the lowest ratio is always built from the smaller ring and the highest from the larger one. Validation is limited but firm: chainring and cog values must be positive numbers, wheel diameter must be greater than zero, and a cadence outside the 20–200 RPM window is discarded and replaced with 90 RPM rather than producing a nonsensical speed. There is no cross-check that your chainring is physically larger than your cog, and no maximum range ceiling, a wide touring triple will calculate just as cleanly as a tight crit setup.
One number deserves a caveat. The “total combinations” tile multiplies the tooth span of your chainrings by the tooth span of your cogs, assuming every tooth count in between exists on your bike. A 34–50 chainring range with an 11–32 cassette reports 17 × 22 = 374 combinations. That is a measure of theoretical spread, not the number of gears you can actually shift into.
A touring bike with a 26/36/48 triple up front, an 11–36 cassette, 700×35c tires, and a rider who spins 85 RPM on the flats. What does that drivetrain give them?
Wheel circumference: π × 692 mm ÷ 1000 = 2.174 m
Lowest ratio: 26 ÷ 36 = 0.72 : 1
Highest ratio: 48 ÷ 11 = 4.36 : 1
Total gear range: 4.36 ÷ 0.72 = 6.04×
Lowest development: 0.72 × 2.174 = 1.57 m per revolution
Highest development: 4.36 × 2.174 = 9.49 m per revolution
Speed window at 85 RPM: 8.0 km/h at the bottom, 48.4 km/h at the top
Read that as a range of roughly 6 to 1. The easiest gear lets this rider crawl up a loaded climb at walking pace while turning a comfortable cadence, and the hardest gear still pushes past 48 km/h on a descent. That spread is what separates a touring setup from a road compact, which typically lands nearer 4×.
Divide your largest chainring by your smallest cog, then divide your smallest chainring by your largest cog, then divide the first answer by the second. A 48/11 top gear and a 26/36 bottom gear gives 4.36 and 0.72, so the range is 4.36 ÷ 0.72 ≈ 6.0×.
Road riders generally sit between 3.5× and 4.5×, gravel riders between 4.5× and 5×, and mountain bikers above 5×. There is no universally best figure, a wider range buys climbing ability at the cost of larger jumps between gears.
It has 22 physical combinations, but most riders use 16 to 18 of them. The extreme cross-chain pairings are avoided to reduce wear and drivetrain noise. The combinations tile on this page measures tooth-count spread rather than counting usable gears.
Development is the distance your bike travels for one full crank revolution, in meters. It matters because it folds wheel size into the comparison, letting you judge a 29-inch MTB wheel and a 700c road wheel on the same scale. It equals gear ratio multiplied by wheel circumference.
No. A wider range almost always means larger steps between adjacent gears, which makes it harder to hold a steady cadence on flat roads. Riders who spend most of their time on gentle terrain often prefer a narrower, tighter cassette over a wide one they rarely use.
Use the cadence you naturally settle into on a normal ride, not a target you aspire to. Commuters often sit near 70–80 RPM, road riders near 85–95 RPM, and MTB riders near 75–85 RPM. Entering an aspirational cadence inflates every speed figure the calculator returns.
Because “700c” describes a rim standard, not an actual measurement, a 700×23c wheel and a 700×40c wheel differ by roughly 34 mm in diameter. Entering the true diameter with the tire fitted is the only way to get accurate development and speed figures.
Yes. Enter the same tooth count in both chainring fields and the same tooth count in both cog fields. The range will read as 1.00×, and the tiles will show the single ratio, development and speed that your one gear produces.
Only the ratio between your smallest and largest chainring matters. Swapping a 50/34 for a 52/36 leaves the range almost unchanged, because both ends scale together, but every ratio inside that range shifts upward, making the whole bike harder to pedal.
The chain will either run slack in the small-small combinations or the derailleur cage will be over-extended in large-large. Add up the difference between your largest and smallest chainring plus the difference between your largest and smallest cog, and compare that total against your rear derailleur’s rated capacity.
The arithmetic is exact for the inputs given. Real-world accuracy depends on your wheel diameter measurement and on whether your tooth counts are correct. Measuring rolling circumference rather than relying on a nominal tire size brings the development and speed figures within a percent or two of reality.
A triple usually wins on raw spread. A 48/36/26 triple with an 11–36 cassette reaches roughly 6.0×, while even a 10–51 MTB cassette with a single ring tops out near 5.1×. The trade-off is weight, complexity and a longer chain.
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