BIKESTEM.FIT

This is a road bike stem calculator that can also help translate measurements between a frame and a fitting.

If you have frame and fit numbers, enter them below and adjust the sliders to see if a workable configuration is available. You want the sum of the frame and the stem to be as close as possible to HX and HY. Or you can just use the sliders as a simple stem calculator.

To save your work, simply bookmark the page.

Current setup

Stem & spacers

Spacer stackMeasure the complete stack along the steerer from the top of the head tube to the stem clamp: the headset top cover plus every spacer. You can add or remove spacers. Follow the frame and fork makers’ limits; carbon steerers are commonly limited to roughly 40 mm.
Stem length
Printed stem angleUse the angle printed on the stem. The up or flipped control tells the calculator how the stem is installed; the diagram shows its resulting angle from horizontal.
Head tube angle
Orientation

Installed angle: Level with the ground

Cockpit position

From the head tube top

Cockpit position: height +38 mm; reach +88 mm.

+38mm height
+88mm reach

Height and reach are measured from the top of the head tube to the handlebar center.

Stem and spacer geometryA fixed-scale side view from the top of the head tube to the handlebar center. One SVG unit equals one millimetre. The current setup is blue.head tube top0°
Head tubeCurrent setup

Your frame

Frame geometry

Your fit target

Handlebar center

HY and HX are measured from the bottom bracket to the center of the handlebars. This article is a good explanation of why these measurements matter.

Reverse solve

Matching setups

Add frame stack, frame reach, HY, and HX to see matching setups.

Your setup is saved in the page address, so bookmarking or sharing the page preserves it. Questions or bugs? Email rswerve@gmail.com or open an issue on GitHub.