What is Chain Length? Sizing Guide & Calculator
Chain length is the total length of your bike chain measured in inches or number of links. Learn how chain length affects shifting, tension, and drivetrain performance.
Quick Answer
Chain Length — is the total length of your bicycle chain, typically measured in number of links (ranging from 104-120 for most bikes) or inches. Correct chain length ensures smooth shifting, proper tension, and prevents derailleur damage—too short risks breaking your derailleur, while too long causes poor shifting and chain slap.
What is Chain Length?
Chain length refers to how long your bike chain needs to be to properly connect your chainring to your cassette while allowing the rear derailleur to manage slack across all gear combinations.
Key measurements:
- Links: Standard unit (104-120 links typical)
- Inches: Total length in inches
- Link pitch: 0.5 inches (12.7mm) per link
Why Chain Length Matters
| Issue | Cause | Consequence |
|---|---|---|
| Chain too short | Can't reach big-big gear combo | Derailleur damage, broken hanger |
| Chain too long | Excess slack | Chain slap, poor shifting, dropped chains |
| Correct length | Proper tension in all gears | Smooth shifting, quiet drivetrain |
The Chain Length Formula
The standard formula for calculating chain length:
L = 2 × C + (F + R) / 4 + 1
Where:
- L = Chain length in inches
- C = Chainstay length in inches
- F = Largest front chainring teeth
- R = Largest rear sprocket teeth
To convert to links: divide by 0.5 and round up to the nearest even number.
Typical Chain Lengths by Bike Type
| Bike Type | Typical Links |
|---|---|
| Road bike (2x, 11-28) | 106-110 |
| Road bike (2x, 11-32) | 108-112 |
| Gravel bike (1x, 10-42) | 110-114 |
| MTB hardtail (1x, 10-51) | 112-116 |
| MTB full suspension | 116-122 |
| Single speed/fixie | 92-100 |
How to Check Your Chain Length
Big-Big Test (Too Short?)
- Shift to largest chainring + largest rear cog
- Check derailleur cage isn't fully extended
- If derailleur is maxed out = chain too short
Small-Small Test (Too Long?)
- Shift to smallest chainring + smallest rear cog
- Check chain isn't touching derailleur cage
- If chain is slack or touching = chain too long
Standard Chain Lengths (New Chains)
| Brand | Road | MTB |
|---|---|---|
| Shimano | 116 links | 126 links |
| SRAM | 114 links | 126 links |
| KMC | 116-118 links | 126 links |
Most new chains must be shortened to fit your specific bike.
Calculate Your Chain Length
Use our Bicycle Chain Length Calculator for instant, accurate results based on your specific bike geometry and gearing.