How to Choose the Size of a Road Bicycle

Finding a great-fitting bicycle is challenging. Bike frame sizes and geometries vary between manufacturers, and finding the right frame to fit your body is essential for enjoyable rides. Take your time when shopping for a new bike, and test-ride any frames that catch your eye. Look for these indications of road bike fit.

Things You'll Need

• Measuring tape

Instructions

1. Find the right frame size with your inseam length. Measure your inseam while wearing Lycra cycling shorts to best simulate a riding position. A frame should be about 2/3 the length of your inseam, measured along the seat tube from the bottom bracket to seat post. Because manufacturers vary in the ways they measure their frames, take your inseam measurement to your bicycle shop and ask a salesperson to help you find a frame that fits you.

2. Adjust seat height so that your legs bend about 30 degrees when your feet are at the lowest part of the pedal revolutions. If you have trouble dialing in a good height, or if you must use an extremely long or short seat post, try a different frame size.

3. Position the seat to achieve neutral knee position--your knee should be directly above the pedal axis when the crank arm is forward and parallel to the ground. Move the seat forward or backward to adjust knee angle. Check seat height again, since large changes here may affect knee angle. If you have significant problems finding the right seat position, try switching to another frame.

4. Check that the bike's handlebars are about the width of your shoulders, and that they do not force you to lean too far forward or to crunch up your torso. Changing the stem length may allow a better riding position, but only small adjustments should be needed. The front wheel axis should be almost directly below your face when riding in an aggressive position. Once again, a wrong frame size may cause problems with riding position.

5. Test-ride the bike and make sure you feel comfortable. Ride in both neutral and aggressive positions. Try both sprinting and spinning easily. Listen to your body--if the bike feels wrong, go back to the shop for adjustments or a different size.

Tips & Warnings

• Always be aware of your body on the bike. You should not feel cramped or stretched out, and your legs should feel natural on the pedals. The right frame may be outfitted with wrong components. Try different handlebars, cranks, crank arms and saddles. Ask your salesperson questions, and let him or her know how you feel on the bike.

Resources

• Colorado Cyclist's introduction to bike fit
• Tips for purchasing a road bike