how the bicycle fits your body

Why Good Fit Matters

SECOND TO YOUR ATHLETIC CONDITION, HOW THE BICYCLE fits your body is the most important aspect of riding. You’ll be spending a minimum of an hour in the saddle for many rides on a road bike—and the number one reason people don’t meet their cycling goals is because they’ll find this time increasingly painful. Some will end up abandoning the sport completely, while others may think they just need to “suck it up.” Other than during the initial break-in period on your booty (usually 2 to 4 weeks depending on how often you’re putting rubber to the road), there is no reason to put up with pain caused by the way the bike interacts with your body. Most of the time you’re riding, your bike should disappear beneath you.
Bikes come in different sizes, which are intended as a guide. Brand to brand, the same size bikes change slightly in length and geometries, which is why test-riding to find the best brand for you is so important. Even a bike that’s the right size may need to be adjusted to your body to properly fit for the most efficient and comfortable riding. Since all bodies—including their limitations and history of injuries—are different, it stands to reason that fit will vary quite a bit from rider to rider.
A bike that fits properly can mean the difference between a pain-free ride or possible long-term problems in your knees, neck, back, shoulders, elbows, wrists, hands, feet, or hips. That is a huge potential for injury when the main reasons you’re riding to begin with are to feel healthier, enjoy the outdoors, and gain a little freedom from the doldrums of everyday life.
When thinking about fit, it’s also important to consider what type of riding you hope to do. Bikes built for touring have the rider in a very upright position. There is a more aerodynamic position for recreational and fitness riders, and the position is lower still for racing. You may want to race, but your body’s restrictions (such as a bad back or tight hamstrings) might call for a style that puts you in a more upright position. Be mentally flexible when it comes to where your body is most comfortable on a bike—it may not be what you envisioned, but it will keep you rolling longer.

Bike Fit 101 

The two most important aspects of bike fit are seat height and reach. When you’re shopping for a bike and sit on it for the first time, these are the two indicators that the size is correct. Above is a rough idea of how a bike should properly fit.
The seat should be high enough that you have a very slight bend in your knee when your foot is at the very bottom of the pedal stroke. This gives you the most power with the least chance of injury.
Your reach should be so that your arms and torso make a 45-degree angle over the bike. Too long and it will be hard to reach the handlebars; too short and your knees will be too close to your arms and your back will arch.