Your Drivetrain

How to Use This

1. Pick a preset that matches your current bike, or type in your exact specs.
2. The chart shows speed at four cadence levels for every gear combination. Toggle cadence chips to focus on your preferred RPM range.
3. Check the gradient section to see which climbs each gear can handle.
4. Use the swap simulator to test a single component change, like going from an 11-30 to an 11-34 cassette.
5. Save multiple bike profiles and compare them side by side to see the real impact of a drivetrain change.

Common Mistakes

• Looking at only the biggest and smallest gears. The middle gears matter most for everyday riding and gaps between adjacent gears affect how smooth your shifts feel.
• Ignoring wheel size. A 650b wheel with the same cassette gives you about 7 percent lower gearing than 700c. The tool accounts for this automatically.
• Comparing gear ratios instead of speed at cadence. A 10 percent higher ratio does not always mean 10 percent more speed if you cannot maintain the same cadence in that gear.
• Forgetting that chainline and front-shift quality get worse when you pair very large and very small chainrings. The math might work but the mechanical reality can be noisy and unreliable.

What the Numbers Mean

Gear inches tell you the effective wheel diameter of each gear. Higher values cover more ground per pedal stroke but need more force. A road bike in its tallest gear sits around 112 gear inches. A gravel bike in its lowest gear might be around 27.

Speed at cadence shows how fast you travel at a given pedaling rate. If you lose the plot above 90 RPM, focus on the 60 and 80 RPM bars. If you spin fast naturally, look at the 90 and 100 RPM bars to see where your setup has gaps.

Gradient estimates assume a 75 kg total system weight on dry pavement. Add 10 kg for bags and the max gradient drops by roughly one percentage point. Loose or wet surfaces reduce it further.