Davis Wheelworks Fit Philosophy

Our fitting philosophy has changed considerably through the years. With an educational background in scientific research, decisions are data driven. This type of decision making naturally carried over heavily in to my fit philosophy. The first inclination in fitting was to define key biometrics that could be applied to any athlete. This does a number of things: 1) gives clear, definitive boundaries to “fit” a client into with regards to body position, and 2) makes it easier to teach others how to fit clients. When purely data driven, fit decisions become easy. But are they the correct decisions?

I always hated hearing the comment that “fitting was an art.” From a research background, this comment was almost offensive to me. At the time, I did not think that anything other than an objective analytical approach to fit was valid. So what is different now? Now I see fit, and the role of a good fitter, being extremely multi-faceted. I wrote one time the following about how I feel about fitting: Part analytical Newtonian science, part interpretive Jungian psychology, part Jedi pre-cognition. I still feel this to be true. That last part, the Jedi pre-cognition, is my way of describing the “artistic” part of fit without actually using the word.

The change in my philosophy came about ironically through the application of scientific principles. What is one the most important components of any research? Controls. Without strong, well thought out and defined controls, no significant inferences can be drawn from the resultant data. An engineer colleague of mine from Cervelo, Damon Rinard, once told me when we were having a discussion about a specific study and I was arguing that the controls were weak, something to the effect of, “Well, I guess we throw our hands up and stop conducting new research.” Caught off guard, I found Damon later and told him that this is not at all the outcome I was looking for – in fact, being very scientifically minded I was actually looking for ways to yield higher quality data that could be assimilated into biomechanical assessment. Damon looked at me dryly and simply told me this is the same thing he tells Gerard Vroomen, Phil White and the Cervélo engineers when they tend to make the same argument towards him. “Do we just stop researching? Stop trying to improve?”

Damon’s point was clear – and it caused an intrinsic change in my thought towards fit. The athlete/bicycle system is a turbulent, uncontrolled system. The controls that we apply to any study will inherently be limited and relatively weak. We have to compare results of different studies to attempt to find trends, perhaps not definitive, numerical guidelines.

What I have done for years while fitting, without necessarily recognizing it myself for a long period of time, was to develop a workflow for assessment. A rider must at first be comfortable in the fitting situation – not physically, but socially comfortable with what is going on, what is being asked. If a decent repoire is not developed between the fitter and the client, it will be difficult to make the appropriate assessment. A rider must be comfortable enough to not realize and pay attention to the motions they are making on the bike during a fit. A fitter doesn’t want a client trying to “impress” them, they need the rider doing what they normally do on the bike. The repetitive physical motions, movements, shifting – this tells me more about the athlete’s comfort level than if I straight ask them the question. Nobody wants to announce they have an inordinate amount of uncomfortable pressure in their taint (except perhaps Dave Z), but you can derive this, and drag the truth out of people by watching movements and asking the right questions. Once the barriers to a comfortable, efficient fit are broken down, significant progress is made.

I’ve tried coming up with a written workflow, attempting to have it act as a guide for fitting. “You see this happen, ask this question. Get response A, move to step 2. Get response B, move to step 5.” But, it has been difficult to reproduce. How do you know what to look for, what to focus on first, what questions to ask? This, I suppose, it where the “art” comes into play – because I have a very difficult time describing how to do it otherwise.

Comparisons – Other Fit Systems & Techniques

There are numerous methodologies or systems currently used for fitting techniques. Some of them use a “dynamic” fit – ie, take measurements in real time while a rider is pedaling. Is this better than taking all measurements while a rider is static? In all probability it more simulates what a rider is actually doing on the road. The best example of this system is the Retül technology. Retül uses eight LED markers on a rider to be able to define motion and geometry while pedaling. Although not on the road, it is the closet thing we have to a true dynamic fit. The measurements themselves are incredibly accurate. The problem I have is that random error is still an issue – The LED markers can be placed in slightly different positions by either the same fitter or definitely by different fitters. The LED’s being over musculature changes how they move. I really want to like Retül, however have had a hard time convincing myself because of these inherent issues. However, when applying the logic I mentioned before – remember the “I guess we just stop researching” comment – I think Retül can be a valuable asset if used correctly. From the simple standpoint of data tracking, I think Retül offers a significant advantage.

FIST is the fitting methodology pioneered by Dan Empfield, of Slowtwitch and Quintana Roof fame. Dan came with a set of rules and measurements we can apply to any rider to determine what position they should be on the bike. The methodology here is much like going to the optometrist. We have a specific fit jig, called an EXIT Cycle, on which we can move specific positions of the bike while the rider is pedaling under power. Much like the optometrist, the rider is presented with choices – “ One, or two. Which is better? One, or two?” As such, one can define a riders position in this fashion. FIST postulates that a rider will self select a position that falls into a narrow range of pre-defined angles. Therefore, even without the fit jig, one can uses these pre-defined ranges as a starting point from which to begin a fit.

My feeling is that regardless of fit system or methodology, a fitter needs to be incorporate extenuating circumstances into defining the clients position. Not every rider will fall into a specific, numerically defined range. Paying attention to rider movement, looking at contact point wear patterns, getting the client comfortable in the fit environment, asking the right questions – these are all critical factors that affect the outcome of the fit process. The particular fit system or methodology employed offer great starting platforms, especially when teaching a novice fitter. It gives them tools and guidelines to follow – the rest simply comes with experience.