# BIKE GEOMETRY CALCULATOR

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Compare the geometry of multiple bikes or see the effects of tweaking your bike’s geometry. Modifications include changing fork travel or offset, mixing wheel sizes, installing an angleset or reach adjust headset, changing chainstay length, or installing a different lower headset cup.

The fields near the bottom allow for additional inputs and calculated measurements for optional bike fit comparison, including cockpit dimensions and Rider Area Distance (RAD) calculations.

Note that manufacturers usually round their measurements so the wheelbase, effective top tube, etc. calculated here are shown with decimal places not shown on the official geometry table. Manufacturer geometry tables are known to be wrong or misleading, and this calculator uses tried-and-true trigonometry and linear algebra, so if you notice the calculated values in this calculator are drastically different than the published numbers, there’s a good chance you’re seeing an error in the manufacturer’s data.

This calculator is a combination of the previous two main geometry calculators used on the site.

Click here for a figure demonstrating the geometry measurements included in this calculator. Read this blog post for tips on entering mullet (mixed wheel) bikes into the original geometry column. View the FAQ for more detailed information on how the calculator works.

Check out the Tire Diameter Estimator for some good starting values for use in the calculator.

The calculations rerun each time you update a cell. To keep things running a bit faster, calculations will not update while you are typing. Click outside of the cell to complete your entry.

This page looks best on desktop computers. Request desktop mode if using a portable device.