I wrote previously about the benefits of a professional bike fit and my approach to fitting. Now, I have been fitting for about three and a half months. I think I learn something new with each bike fitting about bikes, riders, and the interaction between the two. I am more perceptive when I see bicyclists on the road as well, analyzing their pedal stroke and fit. Through all of this experience, I have noticed several commonalities.
Cleat position is frequently off, causing the application of force from the rider to the bike to be compromised. The pedal spindle must be coupled with the base of the first metatarsal to allow for the proper application of force.
The saddle is too low, more often than not. This can cause two major problems. First, this can cause anterior knee pain in the short term and knee damage in the long term, hypothetically. Second, decreased power production will result as well. In both cases the knee is bent too far, causing more compression forces in the first case. In the second case, the quadriceps are too far shortened and the glutes too far lengthened to be efficient.
The saddle is not level, sometimes by oversight, sometimes for comfort. Usually, if it is the latter, then something else is wrong and needs to be addressed. This could be the saddle itself or its position or the overall position.
I have had to inform a few cyclists that they have the wrong crank length--usually too long, which can be frustrating and costly. While a variety of crank sizes exist, most off the shelf bikes are assembled with the three most common lengths. The manufacturers are trying to fit the largest spectrum with each frame size but, of course, they cannot match everyone's size. Through my fitting process, when this occurs, the correct position can be achieved with the pedal down, but not with the pedal up. This causes the same challenges as when the saddle is too low.
Handlebar width, when wrong, is usually too narrow. This can affect the ability to control the bike. It may also cause discomfort in the neck, shoulders, and mid back.
Often, the handlebar is not level as well. Just like with the saddle, sometimes this is by oversight. If not, it likely means something else is wrong.
The biggest challenge to achieving a good fit is the potential for high cost. I do not mean just for the cost of the service, which can be significant, but the cost of new parts: handlebar, stem, seat post, crank set, etc. Unfortunately, a good fit frequently costs a fair amount of money beyond the initial cost of the bike. However, if a cyclist is going to ride thousands of miles and spend days in the saddle over a span of years, shouldn't fit be a priority? For the reasons of safety, comfort, performance, and value? Is it not worth the cost and effort to get it right? My answer should be obvious. Of course, the decision is up to each individual cyclist.