How to use this bike gears calculator
This calculator helps you compare bike gearing in practical terms: how hard each gear feels, how far the bike travels per pedal turn, and your estimated speed at a chosen cadence. Enter your chainring teeth, cassette teeth, wheel diameter, and cadence, then click Calculate Gears.
- Front chainring teeth: one or more values like 50,34 for a compact road crank.
- Rear cassette teeth: values like 11,12,13,15,17,19,21,24,28.
- Wheel diameter: common values are around 27–29 inches depending on setup.
- Cadence: most riders cruise between 75 and 95 RPM.
What the numbers mean
1) Gear ratio
Gear ratio is front teeth ÷ rear teeth. A larger ratio means a harder gear and more speed per pedal stroke. A smaller ratio is easier for climbing and staying comfortable on long rides.
2) Gear inches
Gear inches convert ratio into an old but useful standard: ratio × wheel diameter. It gives a quick feel for how “big” or “small” a gear is. Higher gear inches favor speed. Lower gear inches favor torque and control.
3) Development (meters per crank revolution)
Development tells you how many meters your bike moves forward with one full turn of the cranks. It is ideal for comparing setups across wheel sizes because it translates gearing into real road distance.
4) Speed at cadence
Speed depends on both your selected gear and cadence. The same gear can feel very different at 70 RPM vs. 95 RPM. This calculator estimates speed in both km/h and mph so you can match gearing to your training and terrain.
Choosing the right gearing for your riding style
Road riding
Road riders often use 50/34 or 52/36 chainrings with 11-28, 11-30, or 11-34 cassettes. If your routes are hilly or your rides are long, slightly easier low gears can improve consistency and reduce fatigue.
Gravel and mixed terrain
Gravel typically rewards wider cassette ranges. A 1x drivetrain with a 40T chainring and 10-44 cassette gives strong versatility. If you spin out too early on descents, increase chainring size; if climbs are brutal, reduce chainring size or add larger rear cogs.
Mountain biking
MTB setups prioritize climbing and control. Typical combinations include 30T or 32T front with 10-51 rear. Focus on getting low enough gearing to keep traction and cadence on steep technical trails.
Practical tips before changing components
- Check derailleur capacity and max cassette size before buying parts.
- Compare your current lowest gear to the one you plan to install.
- Use cadence-based speed to estimate race pace and training intervals.
- Don’t chase top-end speed if your local terrain demands climbing gears.
- Small changes (like 2 teeth on the chainring) can have a noticeable effect.
Common gearing mistakes this calculator helps avoid
Many riders choose components based on what friends run or what came stock on the bike. The better approach is matching gears to your fitness, terrain, and preferred cadence. This tool makes that process objective. Instead of guessing, you can compare exact ratios, speed ranges, and climbing gears before spending money.
Use it whenever you are planning a cassette swap, chainring size change, or a new bike build. A few minutes of calculation now can save months of discomfort later.