Frame size

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 (C.T.). The instruction below explain how to measure a classic road bike. 




The frame size is the height of a bicycle. We want to make sure you pick the frame size that’s best for you to make sure you have the smoothest and safest ride possible. Don’t know where to start? We’re here to help.

  • 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.
  • 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.
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