How to Measure a Road Bike Frame

Road bikes are a great option for biking when high-end speed is your goal. Because of the design, these types of bikes tend to be a little less comfortable to ride than mountain or hybrid bikes. In order to make them as comfortable as possible you need to find the right size bike for you. A bike that does not properly fit the rider can lead to an uncomfortable riding position, inefficient pedaling and possible injury. If you know what size bike you need, the next step is to find the right bike.

Things You'll Need

  • Tape measure
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Instructions

    • 1

      Begin by looking on the bike frame itself for any indication of what the frame size may be. Some bike manufacturers place this on the frame, so to save yourself some time measuring the frame check for the size first. If the frame size is not on the bike, you will need to measure.

    • 2

      Stand the road bike up; lean it against a wall or use the kick-stand if the bike comes with one. Road bikes are not measured front to back, nor are they measured from the ground up, so the amount the bike is leaning is unimportant.

    • 3

      Locate the center hub. The hub is the small wheel in the middle of the bike, which the pedals are attached to. In the center, there will be a bolt that runs through the middle that attaches the two pedal cranks to the hub. This is called the crankshaft.

    • 4

      Place the end of the tape measure in the middle of the crankshaft. There are two options for finding the correct frame size. The first is to measure the distance from the crankshaft to where the seat post meets the seat tube. The second, and more common, method is to measure the seat tube to the middle of the top tube, which is the top part of the frame and runs horizontal to the ground. There will be a post that runs straight up from the crankshaft to the seat called the seat tube. Measure this post to the point where it meets the seat post. This measurement is the frame size of your road bike. The most common method of measurement with road bikes is in centimeters, but inches also can be used. To determine the centimeter frame size multiply the number of inches that you measured from the crankshaft to the middle of the top tub by 2.54.