How to Measure a Hardtail Mountain Bike Frame

Hardtail mountain bikes have front suspension only, which makes them a favorite among trail beginners and mountain bikers shopping on a budget.

Many hardtail bikes are used for serious trail riding, so knowing how to measure a hardtail mountain bike frame and choose the right fit is important for comfort, safety, and performance.

On this page, you’ll find a handy interactive online calculator that streamlines this process and teaches you everything you need to know about hardtail bike frame measuring.

Follow the simple steps below!

How to Measure a Hardtail Mountain Bike Frame?

Hardtail mountain bikes are measured based on the seat tube length, the same as most other types of bikes. The measurements are shown in inches, but some manufacturers also use size classes from XS to XXL.

You can follow the measuring instructions below to determine your bike’s seat tube length and then simply choose it from the drop-down menu of our online calculator.

You’ll then be shown a printable rider height and leg length size chart for that frame size, which you can use to determine the best possible fit in seconds!

Frame Diagram

Measuring Instructions

Identify the top of the seat tube, where the seat clamp holds the seat post.
Identify the center of the bottom bracket (it's the axle that holds the crank arms together).
Measure the distance between the two points (C-T) - this is the length of the seat tube.
Record your measurement in both centimeters (cm) and inches (to the nearest half-inch).
Select your bike size from the drop-down on the right to see a rider height chart.

Hardtail Mountain Bike

Rider Charts

Once you know your bike's frame size, select it from the drop-down to see how tall riders should be to use this bike.

Notes

Center to Top (C-T) - This is the length of the seat tube, measured from the center of bottom bracket to top of the seat tube.

Metric (cm) - Road bikes are measured in centimeters.

Frequently Asked Questions

1. How do you measure a hardtail frame?

Hardtail mountain bike frames are measured based on the seat tube length. The seat tube is measured from the center of the pedal crank axle to the top of the seat tube, where the seat post enters the frame. This measurement is shown in inches, but some manufacturers also use size classes from XS to XXL.

2. What size is a 27.5 bike frame?

The number "27.5" refers to the wheel diameter and has nothing to do with frame size measurements, such as seat tube length and top tube length. This is a common misconception many people have, but wheel diameter should not be used to determine the mountain bike frame size and fit, unless it's a kids' bike.

3. What size hardtail mountain bike for my height?

To determine the right size hardtail mountain bike for your height, you should first measure your height and, optionally, also measure your inseam length. Then find a mountain bike size chart or an online calculator and compare your measurements with the available frame sizes expressed in inches or size classes from XS to XXL.

4. Is it better to have a MTB that is too big or too small?

If you are in-between two mountain bike frame sizes and you need to choose between a smaller or a bigger size, it's always better to choose a slightly smaller frame. This is because it is much easier to adjust the fit of a slightly too small bike than that of a slightly too large bike.