All you wanted know but were afraid to ask...
November 20, 2008
Ouch, My Knee! Is There a Bike Fitter in the House?
By CHRISTOPHER PERCY COLLIER
TAD JACOBS loved cycling. The 44-year-old arborist from northern California used to ride two to three times a week to stay in shape. But while pedaling, he suffered muscle soreness in his lower back and joint stiffness in his shoulders. At home, the discomfort worsened.
Then he booked an appointment with Paul Kundrat, a specialist in biodynamics at the Endurance Performance Training Center in Mill Valley, Calif.
During a two-hour session, Mr. Jacobs saw computer-generated data related to his problem. Lasers made precise three-dimensional measurements of his body. Range-of-motion tests were performed. Adjustments were made, and Mr. Jacobs’s pain dissipated.
Six months after the appointment, he was riding 200 miles a week, more than twice his previous distance. “It was amazing,” Mr. Jacobs said. “I haven’t iced my knees since.”
Mr. Kundrat did not use intensive physical therapy, trigger-point massage or faith healing. Nor was the treatment based around hypnosis, acupuncture or heavy doses of pain medication. All it took to stem Mr. Jacobs’s discomfort was a series of measured tweaks to his bike.
For recreational cyclists, this procedure, called a bike fitting, used to be a relatively informal, even minor, affair. After choosing a brand and a model, a buyer would then straddle a few different bike frame sizes, raise or lower the seat of the best fitting one, and be done with it as a clerk looked on.
But in the last decade a far more involved fitting process previously reserved for professional cyclists has mushroomed into a mainstream offering found at scores of bikes shops and training centers around the country.
During a professional bike fitting, the adjustments made are so minute that they are typically measured by the millimeter. The process, which mixes a knowledge of cycling biodynamics with bike mechanics, is touted for its ability to increase comfort, offer enhanced pedaling efficiency and lower the risk of repetitive-use injury. It is not cheap: a two-hour appointment costs $150 to $400.
“It’s not a cure-all,” Mr. Kundrat said, “but you’d be hard-pressed to find someone who, after doing it, thought it wasn’t worth the money.”
The technology put to work in a bike fitting is often an attention-grabber. Lasers, cameras, data readouts and computer imagery that can be manipulated to be seen from multiple views add a certain sizzle to a process that was previously, more often than not, an eyeball estimation.
A system called Retül, for instance, uses three-dimensional motion-capture technology. Eight light-emitting diodes are placed at various key points on a cyclist’s body. When the cyclist gets on the bike and pedals, they flash every 2.1 milliseconds reportedly to deliver 29 full sets of body data" to a central computer. And yet, according to the very best bike fitters in business, it is the experience level of the technician, not the technology or the cost of the service, that most accurately determines fitting quality.
“We like to say that you can give a monkey a machine gun, but that doesn’t mean he’ll know how to use it,” said Sean Madsen, a biomechanist at the Boulder Center for Sports Medicine in Colorado, which is considered to be among the best fitters in the country.
Colin O’Brien, the owner of Cronometro, a custom bike shop in Madison, Wis., that charges $240 to $290 for its biodynamic bike fit, said: “There are probably about 12 to 15 bike fitters in North America that have elevated the bike-fitting process to an art form. Then there are the between 50 to 100 that offer upper grade fittings, and thousands more who have gone through the bike fit classes offered by Specialized and Serotta,” the bike makers.
Hot foot. Tingling toes. Hand numbness. Lower-back soreness. Hamstring discomfort. The alleviation of those types of pain complaints, all common among cyclists, is the usual justification offered for the time and money spent on this type of fitting. To the trained eye of a bike fitter, there are certain clearly recognizable alterations that can be made to eliminate pain that, as Mr. O’Brien said, “you shouldn’t be feeling.”
Knee pain in the patella is often alleviated by moving the seat forward or backward. Neck discomfort can be resolved by moving up the handlebars. Lower-back pain is sometimes lessened by marginally lowering the seat. The significance of these seemingly inconsequential alterations, Mr. O’Brien said, becomes clear when one is reminded that, over the course of a two-hour ride, a cyclist will make about 10,000 pedal revolutions. The pain and discomfort may be dull at the outset, but it can gradually intensify.
“We think the key to a good fit is balance,” said Aaron Hillebrand, a bike fitter with Signature Cycles, a New York City company that reports doing 10 to 20 fits a week from January to August at the cost of $375. “We make sure your body is fully supported skeletally.”
About 75 percent of the cyclists fitted, Mr. O’Brien said, book appointments because of pain or discomfort. The rest, he said, are seeking greater speed and efficiency.
Jeff Gelt, the owner of the Central Wheel bike shop in Farmington, Conn., sought a professional bike fit before a multiday cycling trip to the French Alps.
“At speeds of 50 miles per hour, my bike felt unstable,” he said.
Over the course of his two-hour fitting, a technician properly identified the cause of his high-speed wobble (an elevated center of gravity) and made the proper adjustment (a slight lowering of the seat).
After the fit, Mr. Gelt also found he could go measurably faster while riding at the same level of exertion. “I was so impressed I hired a specialist to do this in our shop,” he said.
For Mr. Kundrat, the fitting starts with a series of body measurements. He begins at the foot and works his way up. He uses a device resembling a large protractor to take angular measurements at the knee and a laser to take others. He asks his riders not only to bring their bikes, which are locked into an elevated stand but also to bring all the gear they would usually wear. Sometimes, he said, neck pain is reduced by simply removing the visor on a rider’s bike helmet, or by wearing different eyewear.
Mr. Kundrat will change bike seats, handlebars or bike stems if necessary. He may swap out one component on a client’s bike for a better fitting one. He also makes the series of minute adjustments that are specific to the rider’s particular body and shape after watching him or her ride — something the Retül system does electronically in other fitting environments — such as raising the seat; pushing the handlebars forward; being sure that the bike cleats are properly positioned. If one leg is shorter than the other (it is rare to find a human body that is completely symmetrical) he will add a shim.
THE session ends with a stroke analysis. As the cyclist pedals, a bar chart of the power output shows up on a computer screen with every colored band an indication of a 15-degree increment of the rotation. For beginning riders, more power is usually employed during the downward pushes on the pedal, which shows up as a wave on the bar chart. Instead, an even distribution of power throughout the rotation is desired.
“You should be pulling back, pulling up, and then kicking that pedal over,” Mr. Kundrat said.
All of the bars should be the same height. Though the changes may not be visibly noticeable at the end of fitting, cyclists often immediately feel the difference. Nagging pain that previously worsened over the course of a ride can suddenly cease to exist.