How to Measure a Road Bike Frame

Whether you’re riding a road bike to join a local cycling group, do a casual weekend ride, or test your limits in a race, your road bike’s frame size is key for a positive riding experience.

Knowing how to measure a road bike frame will ensure you feel comfortable and pain-free, and maximize your performance potential.

If you’re not sure how to do that, follow our step-by-step guide below and our online calculator will tell you all you need to know in seconds.

How to Measure a Classic Road Bike Frame?

Classic road bikes are measured by the length of the seat tube, and the measurement is expressed in centimeters, not in inches.

While the seat tube is the most important metric, you should also consider the top tube length, especially if you are between two sizes.

Our calculator below lets you choose your seat tube length from the drop-down menu and then shows you a detailed size chart with the recommended rider height and inseam length for that size.

If you’re not sure how to measure your classic road bike’s seat tube, you can start by following the instructions below.

Frame Diagram


Measuring Instructions

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


Classic Road 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.


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.


More on eBicycles:

Measure Road Bike Frames - (Classic | Compact | Mixte)

Measure Mountain Bike Frames - (Rigid | FS | Hardtail)

BMX Bikes - (Freestyle | Racing)

Kids Bikes - (Balance | 12 | 16 | 20 | 24)