Chain Length Calculator
Calculate the perfect bicycle chain length for optimal drivetrain performance
Calculate Chain Length
Distance from bottom bracket center to rear axle center
Count or check stamped number on largest chainring
Count or check stamped number on largest cassette cog
Standard bicycle chains use 1/2" (0.5") pitch
Simple method recommended for your chain stay length
Chain Length Results
Formula Comparison:
Installation Tips:
- • Always round up the number of links when cutting chain
- • Ensure you have a compatible master/quick link
- • Break chain so both ends terminate in inner plates
- • Account for master link in your total link count
- • Test shifting through all gears after installation
Chain Compatibility by Speed
Example Calculations
Road Bike
Chain Stay: 16.5"
Front: 50T (compact double)
Rear: 28T (11-28 cassette)
Result: ~52.75" / 106 links
Method: Simple formula
Mountain Bike
Chain Stay: 17.2"
Front: 32T (1x drivetrain)
Rear: 50T (11-50 cassette)
Result: ~55" / 110 links
Method: Simple formula
BMX Bike
Chain Stay: 13.5"
Front: 25T
Rear: 9T
Result: ~35.5" / 72 links
Method: Rigorous formula
Key Chain Components
Chain Stay
Distance from bottom bracket to rear axle
Chainring
Front gear attached to cranks
Cassette/Cog
Rear gears on wheel hub
Chain Links
Individual chain segments (standard 1/2" pitch)
Measurement Tips
Chain Stay Length:
Measure from center of bottom bracket to center of rear axle. Use a ruler or measuring tape.
Counting Teeth:
Count all teeth on largest chainring and largest rear cog. Often stamped on components.
Chain Installation:
Always test shift through all gears after installing new chain to ensure proper length.
Understanding Bicycle Chain Length
Why Chain Length Matters
- •Performance: Correct length ensures smooth shifting and efficient power transfer
- •Component Life: Prevents excessive wear on derailleur and drivetrain parts
- •Safety: Prevents chain dropping off or breaking under load
- •Full Gear Range: Allows access to all gear combinations
Chain Length Consequences
Too Short:
Excessive tension, limited shifting, component damage
Too Long:
Chain slap, dropping off gears, poor shifting
Formula Selection Guide
Simple Formula
Best for chain stays ≥ 15 inches and standard setups:
L = 2 x C + F/4 + R/4 + 1
Rigorous Formula
More accurate for short chain stays < 15 inches:
L = 2 x √(C² + (0.0796 x (F-R))²) + (F+R)/4
Installation Notes
- • Most chains use standard 1/2" pitch between rivets
- • Always round up when calculating number of links
- • Consider master link in total link count
- • Test all gear combinations after installation