The Importance of a Proper Bike Fit November 29, 2006
Topics: Fitness, Cycling

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We often use the phrase, "it fits like a glove" but that phrase doesn't usually apply to bicycles. According to a recent study in the Sports Medicine Journal, 85 percent of cyclists experience some form of pain in the knees, neck or shoulders, wrist and hands, buttocks or the back. How can the bicycle, an 200-year-old invention that has retained the same basic diamond-shaped design for the last 100 years, still cause humans so much pain?

"People should get a bike fitted to their individual needs to optimize comfort, performance and safety," says cycling coach Jerry Gerlich of Castle Hill Specialized Fitness.

The answer lies in the fit. " Whether you're a recreational or elite cyclist, if you don't fit the bike to the body you'll end up fitting your body to the bike. You can develop discomfort and compromised performance at the least. An inefficient and uncomfortable position could also lead to permanent injuries and crashes. People should get a bike fitted to their individual needs to optimize comfort, performance and safety," says cycling coach Jerry Gerlich of Castle Hill Specialized Fitness. "A properly fitting bicycle is easier and more predictable to operate."

Bicycles come in various sizes based on thousands of possibilities because manufacturers combine framing tubes of differing lengths with several sizes of wheels. Mainstream bicycle manufacturers create bicycles based on average human body sizes, much like clothing manufacturers do. However, one size does not fit all.

The standard bike shape also is not so standard anymore. Odd-shaped tubes that sometimes slope with various front and back ends make for error when trying to set a standard formula for fitting a bike to an individual user.

Many people have purchased a bike by its general size, color, price or brand. They may try it on by standing over the top tube to see if their feet touch the ground, thinking that is good enough for proper fit. Others purchase a bike based on measuring their inseam and using a formula to select a bike frame. This measurement does basically the same thing as the stand-over test. For the bike actually to fit a person propertly, it is necessary to take many more measurements and make adjustments to the frame, handlebars, pedals and brakes to suit the individual rider.

"Ergonomics is the study of how humans and objects interact safely and efficiently. Some may argue that painless interaction between humans and objects is also a criteria. Shoulder width, foot and leg length, torso and arm length are measurement factors that affect how a bike fits. Flexibility, leg length discrepencies and core strength also need to be assessed.

"The typical client I see at Castle Hill is a rider looking to optimize comfort and performance," emphasizes Gerlich. "Most riders go with the frame-fitting position provided when first purchasing a bike. As we age, we can develop over- or underuse issues and add new aches and pains thata can be attributed to riding. In the last twenty years, engineers and designers have created bicycle saddles that go a long way at relieving pain, by inserting gel into the seat or cutting a groove down the middle of the seat to relieve pressure on the perineal area."

The bicycle and the body make contact at three points; the gluteous maximus (buttocks) with the seat, the hands with the handlebars and the feet with the pedals. Determining the frame's geometry and how all of the components interact with your body's dimensions combined with knowledge about how you want to use the bike is the job of the professional bike fitter. People who are serious about comfort and performance are always looking for the optimal riding position," says Gerlich.

At the bike fitter's disposal are various tools to record a cyclist's measurements, analyze them and recommend geometry (adjustments) to optimize the bike's comfort and performance for the individual. While a quick bike fit can be done in a few minutes, it will only provide you with information to purchase a bike that generally works for you. In order to get the most performance out of the bike or to feel the most comfort, a performance test should be conducted. By asking many questions about your riding style, taking measurements of your body and plotting other variables such as age, gender and physical condition, the bike fitter can make you go faster or create more power, can make you more comfortable, or make you more efficient.

After arm lengths, inseams, feet, torso and shoulders have been measured, two fitting options are available. The computer will take your body's dimensions and based on thousands of other cyclists in the database, the geometry for a bike will be produced. This geometry is the recommended setup for your bike, either to purchase or to change settings on an existing bike. The bike fitter can also take the recommended geometry and use it as a guide for a later test.

imageA second, more complicated, approach,transfers your bike's existing geometry to a virtual reality bike, such as a Velotron, that is connected to a computer. By riding the Velotron for a specific time and RPM, power output and pedalling efficiency can be observed and recorded. The bike fitter tweaks the cycling simulator - making changes in such things as the saddle, the cleats on the cycling shoes, the handlebar position - then runs the test again. The bike fitter may consult the computer's recommendation on geometry or new positioning will be made based on experience. This procedure is run again and again until the optimum positions are found for the handlebars, seat and pedals.

"Our fitting process takes about two hours," says Gerlich. "Several measurements are taken to insure accuracy. We then experiment with small adjustments on theVelotron simulator to find a position that provides comfort and performance."

He cautions that a recreational rider should achieve a certain amount of fitness before looking to bike adjustments for pain relief. "Initial pain in the buttocks, neck, shoulder and lower back can be expected for a neophyte rider," says Gerlich. "However, once the rider has developed enough strength and endurance to cover about 15 miles without exhaustion, the pain should not endure."

Pain can develop from improper riding position, poor posture and poor technique in relation to accelerating and steering the bicycle. Most riders can expect general soreness, especially after a vigorous ride with an abundance of climbing. It should be siilar to general soreness after a weight training session using good form.

A professional bike fitting consultation can cost more than a hundred dollars, so it's not for neighborhood riders. But for serious enthusiasts, it can make a real difference. Another benefit is that once you know the geometry, you can transfer the correct position to another bicycle. So if you travel and choose not to take your own bike with you, take the measurements instead. That way, no matter where you are riding or what bike you're on, you'll reduce the pain and enjoy the ride more.

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