Bicycle frame size is an important consideration when purchasing a new bicycle. The frame size has an effect on your comfort when sitting, reaching forward for the handlebars, mounting the bicycle and extending your legs to pump the peddles. A poor frame size selection may not only result in discomfort when riding, but could also cause injury. You can use two different calculations to determine the correct bicycle frame size for your body.
Step 1
Measure your inseam with measuring tape from your groin to the floor when not wearing footwear, according to GroupTrails.com. Convert the number in inches to centimeters by multiplying the result by 2.54.
Step 2
Determine your seat tube length, which determines the height of the bicycle frame, by multiplying your inseam in centimeters by 0.67, according to ColoradoCyclist.com. For example, if your inseam is 75 cm, the formula is 75 x 0.67. The answer, and your right seat tube length bicycle frame size, is 50.25 cm.
Step 3
Find the top tube length, which is the tube running from the seat to the handlebar tube, by multiplying your inseam in centimeters by 0.65. Using the previous example, the formula is 75 x 0.65. The answer, and your right top tube length bicycle frame size, is 48.75 cm.
Step 4
Measure for a mountain bike by following Step 2 and subtracting 10 cm to 12 cm from the result. Test the size of the mountain bike out before purchasing as this is an approximate size for your inseam.
Tips and Warnings
- The sizing methods described in Steps 2 and 3 are independent methods for determining a bicycle frame size. Choose one or the other when determining your frame size. Test your bike before making a purchase to ensure the frame size is comfortable.
Things You'll Need
- Measuring tape
- Calculator
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