CalculatorsStack and Reach Ratio Calculator

Stack and Reach Ratio Calculator

Stack over reach is the quickest way to see if a frame wants your hands low. The ratio ignores stem and spacers, so it compares frames rather than a finished bike.

Inputs

Stack (in)Reach (in)

Results

Stack / reach: 1.49
Position code: 3

How the number is made

Ratio = stack ÷ reach. Codes use a strict lower bound: below 1.35 is 1 (race), from 1.35 up to but not including 1.45 is 2, from 1.45 up to but not including 1.55 is 3 (endurance), and 1.55 or higher is 4 (upright).

Spacers and stem angle move the bars without changing this frame ratio.

Position code. 1 race, 2 fast endurance, 3 endurance, 4 upright.

Frame versus finished bike

Add the stem calculator after this one. A −17° stem drops the bars; it does not rewrite the frame ratio printed on the geometry chart.

Related calculators

Stem Length and Angle Calculator
Turns frame reach into where the hands actually land.
Bike Frame Size Calculator
Pick the centimetre size before you compare two geometry charts.

Questions

What is a normal endurance ratio?

About 1.45 to 1.55. Race bikes often sit at 1.30–1.40 before the slammed stem.

Can a long stem fix a short reach?

A little. Ten millimetres of stem is not fifteen millimetres of frame reach plus a taller stack.

Does 1.45 count as endurance?

Yes. 1.45 starts the endurance band and 1.55 starts upright. A ratio of 1.449 is still the fast-endurance band.

Related gear

Digital angle finder
Confirm the real head-tube angle if you are comparing a flip chip later.
$20–$40

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.

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