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CyclingDetermine the Length of Your Bike Chain Based on Chainring and Sprocket Sizes
Bicycle Chain Length Calculator
Calculate the length of your bike chain based on the chainring and sprocket sizes.
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About the Bicycle Chain Length Calculator
Learn more about the calculator and its creator
Jonas
I'm a software developer and bike enthusiast from Germany. I created this chain length calculator to help cyclists find the perfect chain length for their bike because I couldn't find a good one when I started cycling and bought the wrong chain length one too many times.
How to Use the Bike Chain Length Calculator
This chain length calculator helps determine the correct chain length for your bike. Whether you're replacing an old chain with a new chain or checking your current chain length, this tool provides accurate measurements. Using a chain tool and checking against the original chain can help ensure proper installation.
The Formula to Calculate Chain Length
The chain length calculator uses the following formula to determine the chain length:
L = 2 * C + (F + R) / 4 + 1
Where:
L = Chain length (in inches)
C = Chainstay length (in inches)
F = Number of teeth on the largest front chainring
R = Number of teeth on the largest rear sprocket
Understanding Chain Components
A bicycle chain consists of inner plates and outer plates connected by two rivets. The master link (also called a quick link) joins the chain ends together. Each link measures approximately one inch in length, and the total chain consists of multiple inner and outer plates working together.
Additional Considerations for Chain Length
- Check chain wear using a chain tool
- Account for both front derailleur and rear derailleur clearance
- Consider the largest rear cog and front chainring combination
- Measure the distance between sprockets
- Check if you need extra length for rear wheel movement
- Verify the correct length using a rigorous equation
Input Parameters
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1
Chainstay Length
The distance from the center of the bottom bracket to the center of the rear axle.
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2
Largest Front Chainring
The number of teeth on the largest chainring at the front.
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3
Largest Rear Sprocket
The number of teeth on the largest sprocket on the rear cassette.
Calculation Process of the Chain Length Calculator
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1
Apply Formula
The calculator takes the input values and applies them to the formula.
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2
Unit Conversion
If the chainstay length is provided in millimeters, it's converted to inches (1 inch = 25.4 mm).
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3
Calculate Chain Length
The result (L) gives the chain length in inches.
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4
Calculate Number of Chain Links
The number of chain links is calculated by dividing the chain length by 0.5 (as each link is typically 0.5 inches long).
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5
Round Up
The number of links is rounded up to the nearest even number to ensure a complete chain.
Output
The calculator provides two main outputs:
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1
Total Correct Chain Length
The estimated length of the chain in inches or centimeters.
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2
Number of Chain Links
The recommended number of chain links for your new chain, rounded to an even number.
Important Notes
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1
Estimate Only
This calculation provides an estimate and should be used as a starting point.
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2
Manufacturer Guidelines
Always refer to your bicycle manufacturer's guidelines for the most accurate chain length.
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3
Additional Factors
Consider factors like suspension design and specific drivetrain requirements when determining the final chain length.
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4
Err on the Side of Longer
It's generally better to err on the side of a slightly longer chain, as it can be shortened if necessary.
Use this calculator as a helpful tool in determining your bike's chain length and chain links, but always double-check with professional resources or a bike mechanic for the best results.