A bike that is properly fitted to you can often make the difference between having an enjoyable biking experience and a nightmarish memory.
The right size bike for your body will enhance the transfer of power from your body to the wheels as well as help with your comfort, health, and endurance. Let's start with the basics. Our discussion will center on fitting road bikes. Other bike types, such mountain bikes have different sizing criteria and are not discussed here.
Frame Size
In general we're talking about height and length of the bike frame, which equates to a comfortable clearance over the top tube, as well as a comfortable weight distribution between your hands and seat when leaning over top tube and holding onto the handlebars.
Top Tube Clearance — Put on your biking shoes and while standing on a level surface, straddle your bike. Make sure that when flat footed that your crotch comfortably clears the top tube of your bike — or the bike you are considering purchasing. If you don't have enough clearance, then the size of the bike's frame may be too big for you. If you tower over the top tube, then the frame size is probably too small.
Top Tube Length — Next, have a friend hold the bike while you sit on the saddle, putting your hands on the handlebars. Try different positions of your hands on the handlebars. The weight you place on your hands when holding the handlebars ought to be around 60% of your body weight. The other 40% should be on your saddle.
If you find that more weight is focused on your hands, then the frame may be too long causing you to reach too far. Adjusting the height of the handlebars can also affect this weight distribution so keep that in mind. Older riders with back problems may want to adjust their handlebars to a higher position — which may create more wind drag from a more erect body position. Younger, or more physically fit riders may prefer a more aerodynamic body position for greater speed. The tradeoffs of aerodynamics may come in the form of less comfort. You decide what works best for your needs.
Saddle Height — The optimum height for efficient power transfer from leg to wheels is such that when the downward pedal is at the bottom of its stroke your leg is just shy of full extension when seated squarely. This means just a very slight bend in the knee when when the pedal is at its lowest point. You don't want to hyperextend your leg, which will cause unnecessary knee pain and waste energy.
Saddle Position — Most bicycle saddles have a fore and aft adjustment capability. A good rule of thumb is to position your saddle so that when you're seated in a riding position, the knee of the extended leg is directly above the center of the pedal being extended. If you were to hang a string with a small weight attached to the bottom end of it from the middle of your knee on the extended leg, it would ideally line up with the center of the pedal. Loosen the seat mounting nuts and slide the seat forward or backwards as needed. You can also adjust the saddle to tilt forward or backward, according to your personal preference. Some people prefer a forward tilting saddle to focus the weight on the "sit bones". Others prefer positioning the saddle completely level for more even distribution across the sit bones and the crotch. Bodies are different and personal preference is the rule.
0 Comments