Fixed Gear Ratio Calculator
Use this calculator to estimate your fixed gear setup performance: ratio, gear inches, rollout (development), speed at cadence, and skid patches.
What Is a Fixed Gear Ratio?
On a fixed gear bike, your gear ratio is determined by one front chainring and one rear cog. The formula is simple: gear ratio = chainring teeth / rear cog teeth. Since fixed gear bikes have no freewheel and no derailleur, this one number has a huge impact on your ride feel.
A higher ratio (for example, 50/15) gives more speed per pedal revolution but requires more force, especially for starts and climbs. A lower ratio (for example, 46/18) is easier to spin and better for hilly routes or stop-and-go city riding.
How to Use This Calculator
1) Enter your drivetrain sizes
Input your front chainring and rear cog tooth counts. These are printed on most components.
2) Add wheel diameter
Wheel diameter affects rollout and speed. A common estimate for a 700c road wheel with typical tires is around 26.8–27.3 inches. If you know your exact measured wheel diameter, use that for better precision.
3) Set cadence
Cadence is your pedal revolutions per minute. Typical ranges:
- Easy spin: 70–85 rpm
- Steady endurance: 85–95 rpm
- Fast effort: 95–110+ rpm
What the Results Mean
Gear Ratio
The baseline mechanical advantage. Bigger number = harder gear.
Gear Inches
A traditional way to compare gearing across bike types. It combines wheel size and ratio, making it useful for quick setup comparisons.
Development (Rollout)
How far your bike travels per full crank revolution (in meters). Great for understanding real-world distance covered each pedal stroke.
Estimated Speed
Speed is calculated from development × cadence. It helps you evaluate whether a ratio is practical for your route and preferred pedaling style.
Skid Patches
Fixed gear riders often care about skid patches because they affect rear tire wear. More skid patches generally spread wear more evenly and can extend tire life.
Choosing the Right Fixed Gear Ratio
- Urban commuting: aim for a moderate ratio that handles traffic starts comfortably.
- Flat and fast roads: a slightly higher ratio can improve cruising speed.
- Hilly areas: choose a lower ratio to avoid grinding and knee strain.
- Beginner riders: start easier, then move up after a few weeks of adaptation.
Common Setup Ranges (General Guidance)
- 46/17 to 48/17: versatile, manageable for many riders
- 48/16 to 49/16: sportier street setup
- 50/15 and up: stronger legs, flatter routes, higher cadence control needed
Practical Tips Before You Finalize a Ratio
- Test your ratio on your actual route, not just on paper.
- Prioritize comfort at intersections and climbs.
- Watch knee feedback—persistent discomfort usually means gearing is too tall.
- If you skid frequently, consider setups with more skid patches.
Frequently Asked Questions
Is a higher ratio always better?
No. Faster potential speed comes with harder starts and more fatigue. The best ratio is route- and rider-specific.
What cadence should I target on fixed gear?
Many riders are efficient around 85–100 rpm on flats. New riders may prefer slightly lower cadence at first.
Can this calculator replace a real-world test ride?
It gives strong estimates, but real roads, wind, tire pressure, and your fitness still matter. Use it as a decision tool, then validate outdoors.