CalculatorsOptimal Chain Length Calculator

Optimal Chain Length Calculator

A new chain is sized on the big-big combination, then you never ride big-big. This uses the standard link formula and rounds up to an even number so a quick link can close it.

Inputs

Chainstay (in)Largest chainringLargest cog

Results

Chain links: 110

How the number is made

The inch equation is L = 2 × chainstay-in-inches + largest ring ÷ 4 + largest cog ÷ 4 + 1. Pitch is half an inch, so links = 2 × (chainstay mm ÷ 12.7) + (ring + cog) ÷ 2 + take-up. Take-up is 2 links, or 4 links when the largest cog is 42 T or bigger (Park Tool’s extra slack for a long-cage clutch). Round up to the next even number so a quick link can close.

This bypasses the derailleur, the same way you size on the stand. Full-suspension growth can lengthen the stay at sag. Do not cut until the chain wraps the big ring and big cog by hand. An odd count cannot close on a master link.

Related calculators

Derailleur Capacity Calculator
Length says the chain fits; capacity says the cage can take up the slack.
Bicycle Gear Ratio Calculator
Big-big is for sizing, not a gear you should pedal.

Questions

Why an even number?

A master link joins inner to outer. An odd count leaves two outers or two inners facing each other.

Do I wrap big-big to check?

Yes. The formula gets you close. Wrap big ring and big cog with the derailleur out of the path, then keep the take-up (two links, or four if the cog is 42 T or bigger) before you cut.

When does the chain gain two extra links?

The usual take-up is two links. A largest cog of 42 teeth or more adds two further links, the allowance for a dedicated 1x.

Related gear

Chain tool and quick link
Cut to the even count, then close with a speed-matched quick link.
$20–$50

Disclaimer — no professional advice, no liability

These calculators are simplified estimates for education. They are not a bike fit, a structural inspection, or a torque specification that overrides the number printed on a part. Confirm chain length, spoke length, tire fit and bolt torque on the bicycle before you ride.

These calculators, pages and any related content are provided “as is” and “as available”, solely for general educational and informational purposes. They are simplified mathematical estimates, not a professional bike fit, a structural inspection, a manufacturer torque specification or a training, nutrition or medical plan.

Results can be wrong, incomplete or inapplicable to your frame, wheels, tires, drivetrain or suspension. You must independently verify every figure, assume all risk, and confirm chain length before you cut, spoke length before you lace, tire and rim compatibility before you inflate, and the torque printed on the part before you tighten it.

To the fullest extent permitted by applicable law, the site operator, authors, contributors and affiliates disclaim all warranties, express or implied, and accept no liability for any direct, indirect, incidental, special, consequential or punitive damages, or for property damage, injury, death, business interruption or financial loss, arising out of or related to the use of, or reliance on, these tools or their outputs.

Some jurisdictions do not allow certain warranty exclusions or liability limitations, including for personal injury. In those places, our responsibility is limited to the maximum extent permitted by law. If you do not agree, do not use this site.