Bike Fitting

By: 
Eli Post

Cycling comfort depends on a bike that fits right and efficiently delivers power to the pedals. Many of you have likely had a bike fit at some point, and hopefully learned that your bike must fit well if you are to ride comfortably. An improper bike fit can cause serious discomfort.

Bicycle fitting has traditionally involved various measuring devices and "rules of thumb" such as pedaling is most efficient when you ride with the balls of your feet on the pedals.  As technology has worked its way into bike fitting, the common wisdom has been refined.

Several computer-based systems use infrared LED's (light-emitting diodes) placed on the body in specific skeletal locations. As you pedal with your bike mounted on a trainer, readings capture body motion which the computer processes and uses to generate a report. The bike fitter analyzes and evaluates the data and determines whether there is a need to make adjustments to your bike. The computer-generated photo shows the author being fitted at Grace Bicycles in Holliston, MA.

Several software systems have been designed for bike fitting, but we can't recommend one over the other nor do we suggest one bike shop over another. Each rider will have to determine whether the extra cost is justified. In some cases the eye of a skilled fitter is perfectly adequate and a computer based fitting turns out to be a “glorified ruler" and not a productive use of time and money. In other situations, however, the additional data generated by the computer-based system could make a considerable difference. My own experience might serve as an illustration.

I had a tendency to rotate slightly in the saddle, which caused it to rub and bruise my leg. After about 25 miles on the bike, the discomfort made additional riding difficult. I tried conventional fitting, physical therapy, and more saddles than I will admit to owning.  Finally, when none of these worked, I went the route of a computer-based fitting.  The data showed that one leg was forward of the other as I rode, suggesting a slight leg length discrepancy. A shim placed on the shoe of the shorter leg cured the rotation issue eliminating the pain which had plagued me for months. So I am a believer, but again this process is not for all. I also understand that many who are not in pain, but desire to maximize their performance are also fans.

My example shows the value of a bike fit after a bike has been purchased and ridden for a while.  Bike fits are also used to help select a bike that will work for a rider and/or to build custom bikes, and also to fit the saddle position and stem length to a bicycle that has already purchased.


As I tried to resolve my own pain issue, I found that the old adage applied: to a man with a hammer everything looks like a nail. Often the advice you receive depends on whom you ask. If, for example, you have lower-back pain when you cycle, the bike fitter might suggest that you raise the handlebars, the physical therapist might suggest some stretches and exercises, the family doctor could tell you to lose several pounds, and your significant other might just say “suck it up, cupcake." And you know what?  They could all be right. In fact, sometimes it isn't even clear whether the problem is the bike or the body, but if your bike does not fit, you will eventually hurt, and at that point cycling will no longer be fun.  "Fitting" is becoming more prevalent and is likely to add to the comfort and enjoyment of the bike riding experience.

This article is an update from one that was published in August 2011.

Comments

Joe Parslow's picture

Back "in the day" when I was a runner (late 70's) I developed knee pain problems. As it turned out I had one leg 1/4 inch shorter than the other and the many miles accrued in training for a marathon make this a big problem. One which would never manifest in a lifetime of not running. A 1/8 inch shim in the shoe of the shorter leg solved the problem. Who knew!
Joe Parslow's picture

Back "in the day" when I was a runner (late 70's) I developed knee pain problems. As it turned out I had one leg 1/4 inch shorter than the other and the many miles accrued in training for a marathon make this a big problem. One which would never manifest in a lifetime of not running. A 1/8 inch shim in the shoe of the shorter leg solved the problem. Who knew!