A Common Sense Guide to Bicycles

How to Measure a Classic Road Bike

The classic style road bike frame is most commonly found on road, racing, touring, and commuting bikes. The top tube is parallel to the road, giving the frame more stability and support. The frame size is determined by measuring the length of the seat tube, in centimeters. The instructions below explain how to measure a classic road bike.

Classic road bike

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.

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.

Frame Diagram

Classic road bike frame with seat tube measurement highlighted

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.