A Common Sense Guide to Bicycles

How to Measure a Compact Road Bike

Compact road bike frames have become more common today, especially among urban, city and commuter style road bikes. The downward sloping top tube provides more leg clearance, making it easier to find a bike that fits. The frame size is determined by the length of the seat tube, in centimeters. The instructions below explain how to measure a compact road bike.

Compact road bike

Compact 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.

Frame Diagram

Compact 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.