You'll want to follow the articles in succession, starting with Intro to the F.I.S.T. Method:
1. F.I.S.T. axioms <-- You are here
2. F.I.S.T. protocol
3. Measuring conventions
4. Seat height
5. Cockpit length
6. Hip angle
7. Armrest drop
8. Tools of the trade
9. Your bike's "waistline"
10. Translating fit specs to bike specs
This article is part of a series of article on tri bike fit. Before reading this one, you should've read our introductory article. Nothing we've written in that article is especially groundbreaking or controversial. Rest assured, there is plenty to follow to which certain folks will take exception. And because of this, it's only fair to lay out a few axioms upon which this system is based, so that readers understand the foundation atop which this bike fit system is built. It's only fair we produce these axioms here, because if you don't accept them as truisms you'll probably have a problem with the system built on these axioms. Here they are:
1. MOST PRO TRIATHLETES RIDE ALIKE. Pro triathletes started riding in positions exhibiting bike fit characteristics common one to another, and did so within two years of the introduction of aero bars (in 1987). Furthermore, most good pros ride the same way today as the best pros did in 1990. What do Mark Allen, Paula Newby-Fraser, Scott Tinley, Jürgen Zäck, Wolfgang Dittrich, and Pauli Kiuru all have in common? They were all stars 12 and 15 years ago, and they shared very similar tri bike fit characteristics. What do Normann Stadler, Torbjorn Sindballe, Faris Al Sultan, Peter Reid, Tim DeBoom, Heather Fuhr, Lori Bowden and Natascha Badmann all have in common? They are today's stars, and they not only share bike fit characteristics one to another, they are positioned in ways quite similar to those pros of an earlier generation. These similar characteristics are measurable, identifiable, and we'll identify and quantify them below.
2. FIT, TRIM AGE GROUP ATHLETES CAN EASILY ADOPT THE SAME POSITION AS THOSE RIDDEN BY PROS. What keeps you from the pro podium in the Hawaiian Ironman is not your inflexibility. It's not that you lack the "taint of steel," and that you can't take the pain of your peritoneum on the saddle nose the way Mark Allen could. What keeps you from the podium is that you cannot absorb 400 calories per hour during a race, like Mark Allen could. You heart doesn't have the stroke volume of Spencer Smith's heart. You can't burn the same amount of oxygen per kilogram of body weight per minute as can Peter Reid. In other words, you might not have a pro "motor," but you do have a pro "chassis," and there is no reason why you can't ride in a pro position. Most fit, trim golfers have the physical ability to swing the club like Tiger Woods, and tennis players can hit ground strokes like Venus Williams. Maybe not as hard, or as accurately, but if they don't exhibit the same basic technique it is not because they're physically disqualified from doing so. It's a myth to think triathletes can't ride their bikes in an appropriate fashion.
3. BODIES ARE SMART, AND CAN BE TRUSTED. Riding a bike in the aero position is an elemental exercise. There are few fine points of technique involved. A rider in his best position enjoys what one might call a "nexus of strength": optimized leverage combined with major thigh muscles firing in concert. By happy circumstance, the important elements of tri bike fit—those exhibited by most of the best pros throughout the past 15 years—are freely identified and selected by most of those given the opportunity to find their optimized position. In other words, your body will not betray you.
4. THE OPTIMIZED TRI POSITION REQUIRES MODERATE ATHLETICISM. While an optimized aero position is not difficult to achieve, it requires elements of athleticism in excess of that required for a road race position. While nearly everyone can ride a road race bike in a position not so different from those ridden by professional road racers a smaller percentage, perhaps half to two-thirds of those of those competing in triathlons, can adopt an optimized tri position. This might seem an axiom at cross-purposes with #2 above. Please note, though, the qualifiers, "fit" and "trim."
The axioms above allow us to build a bike fit system.