The Ultimate Bike Gear Calculator
Professional-grade physics tools for cyclists, mechanics, and frame builders. Optimize your drivetrain with precision.
Quick Master Calculator
Why Trust BikeCalc?
Built on engineering standards, verified by mechanics, and free forever.
Verified Algorithms
Our calculators use standard formulas from Sheldon Brown and engineering mechanics. We strictly adhere to ISO 5775 tire standards for circumference data.
Universal Compatibility
Whether you ride a 1x12 MTB, a vintage road bike, or a track fixie, our tools cover all wheel sizes (20" to 29") and drivetrain configurations.
Educational Focus
We don't just give numbers; we explain the 'Why'. Our goal is to help you understand gear mechanics to make better upgrade decisions.
Specialized Tools
Bike Gear Ratio Calculator
Calculate gear ratios for any setup.
Gear Inches Calculator
Compare gearing across wheel sizes.
Cadence to Speed
RPM to MPH/KMH conversion.
Fixed Gear & Skid Patches
Optimize skid patches for fixies.
Chain Length Calculator
Calculate required chain links.
Wheel Circumference
ISO/ETRTO to circumference.
Gear Ratio Charts
Interactive gearing tables.
MTB Gear Ratio
Optimized for Mountain Bikes.
Road Bike Gear Ratio
Optimized for Road Cycling.
Single Speed Calculator
Simple ratio tool for SS bikes.
Key Concepts Demystified
Understanding these terms is the key to choosing the right cassette, crankset, or tires for your riding style.
Gear Ratio
The mechanical advantage of your drivetrain. Calculated as Chainring ÷ Cog. A ratio of 3.0 means your rear wheel spins 3 times for every 1 pedal stroke. Higher is harder/faster; lower is easier/slower.
Gear Inches
A normalized value that factors in Wheel Size. Essential for comparing road bikes (700c) against MTBs (29"). It represents the diameter of the drive wheel if you were riding a direct-drive penny-farthing.
Development (Rollout)
The actual distance traveled in meters (or feet) for one complete revolution of the crank. This is the most "real world" metric for how much ground you cover per pedal stroke.
Skid Patches
Crucial for fixed gear riders. It's the number of unique points on your rear tire that will contact the ground when you skid. More patches = longer lasting tires. Always avoid 1-patch ratios!
Why Use Our Calculator?
Whether you are a competitive cyclist, a fixed-gear enthusiast, or a mechanic, understanding the physics of your bicycle's drivetrain is crucial for performance. Generic spreadsheets are hard to read on mobile devices, and basic math often ignores the nuance of wheel circumference standards (ISO 5775).
BikeCalc solves this by providing instant, visual, and accurate tools. We help you plan your next cassette upgrade, determine the right chain length for a new build to avoid snapping a derailleur, or simply satisfy your curiosity about how fast you can go at 120 RPM.
For the Mechanics
Building a mullet drivetrain (Road shifters + MTB derailleur)? Use the Chain Length Calculator to ensure your chain is long enough for the 52t cog but short enough to maintain tension.
For the Racers
Optimizing for a Time Trial? Use the Gear Chart to find a cassette with 1-tooth jumps in your target speed zone, keeping your cadence perfectly steady.