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.

Image Tad Jacobs. Credit... Heidi Schumann for The New York Times

“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.