Proper Bike Fit for Triathletes
April.03 by Dan Empfield
(www.slowtwitch.com)

This series of articles is the first major overhaul of my writings on this subject in over a decade. I've embroidered around the edges and spruced up my grammar, but as I write this, in the shadow of the Second Gulf War, it must be acknowledged that most of what resides in this section has remained unchanged since shortly after the First Gulf War. I thought it worth a revamp.

Why now? Because every few weeks I host between seven and ten bike shop professionals and triathlon coaches and I teach them how to fit their customers to their bikes for use in triathlons. That's caused me to have to take a very hard look at what I do. While nothing has dramatically changed in my approach, the way I teach it has changed, and is changing. As a result, the way I present it to my readers can and ought to change as well.

THE BASICS OF BIKE FIT
WHICH GEOMETRY STYLE IS RIGHT FOR YOU?
WHY MUST SEAT ANGLES MATCH FRONT END CONFIGS?
CLEAT MOUNT
DETERMINING WHICH POSITION IS BEST
A NEW FORMULA FOR SLACKER-ANGLED ARMREST DROP?
HOW TRI-SPECIFIC GEOMETRIES MUST BE RIDDEN
HOW DO YOU CHOOSE A BIKE AND H'BARS?

THE BASICS OF BIKE FIT

The steps to achieving a good bike fit are few and easy. First, you must decide which style of geometry is for you. Against the backdrop of some immutable rules that apply to every position you choose, you're free to ride however you want. You can ride with a seat angle of 74 degrees or with 81 degrees. There is no necessarily perfect or special, or even tri-specific geometry to which you ought to aspire.

Each of the three riders represented at right are in a position that is appropriate for triathlon racing. One immutable rule is that the range of motion in which your thigh musculature operates ought to be biomechancially sound. We might roughly refer to a "hip angle" that is formed by using the bony protrusion of your hip (greater trochanter) as the apex, and with that angle's lines being: 1) one that run from the hip to the foot, and, 2) from the hip to the bony protrusion of the collarbone.

That hip-to-the-foot line is a little tough to nail down. Ought it to be from the hip to the bottom bracket? Or to the maleolus (bony protrusion of the ankle)? Or to the pedal axle? If so, where? At the bottom of the pedal stroke? With the crank in line with the seat angle (or relative seat angle)? If it's the hip angle you're measuring, why measure the angle in its most obtuse configuration? Why not at its most acute, when your foot is at the top of the pedal stroke?

All these are valid observations, but it doesn't much matter. If the proper bike fit is in fact proper, it doesn't matter where you measure, but each of these lines formed by the proximal point (hip) and the terminus at the line's distal point (ankle, BB, pedal axle, whatever) is going to change depending on which distal point you choose. I personally favor the pedal axle at the bottom of the pedal stroke, and my definition of "bottom" (for the purposes of measuring this angle) is not at 6 o'clock, but at the point where the axle is in line with the seat angle.

The preferred angle is 90-95 degrees, and while I don't like angles more acute than that, I don't mind a more obtuse angle, up to a point. I can in some cases live with 100 degrees. I have a problem living with an angle greater than that. As long as this is your hip angle, however, it doesn't matter to me whether you're riding at 71 degrees or 81 degrees of seat angle. Realize, however, that as you rock yourself back in the saddle you're rocking yourself up in front, that is, your back will not be as flat and you will probably be punching a larger hole in the wind as you propel yourself forward.

Why would one want to be less aerodynamic? Comfort, plain and simple. Rotating one's body complex forward means you're no longer sitting on that padded place God provided for you. You're now resting on the saddle in places God did not intend in his infinite wisdom for you to rest. Perhaps the Grand Design did not contemplate triathlons.

When one rocks all the way back—the Green Rider—this is a road race position, and a proper road bike fit is easy to achieve. By “road bike” I’m talking about the Trek Lance Armstrong rides on those days in France when the whole pack starts together. No aero bars on that bike.

If you’re a triathlete, however, you no doubt feel compelled to have triathlon bars on your bike. You shouldn't. Not necessarily, at least. There is nothing wrong with riding—even while racing in a triathlon—on a road race bike with road bars, STI or Ergopower shifting, and no aero bars whatsoever. In fact, if you're new to the sport, that's probably the best choice you could make, especially if you're brand new to STI-style shifting and clipless pedals, and if you've never before ridden with tri bars. All that is hard to learn in one fell swoop.

Besides, in another month, or two, or six, you can bring your bike into the shop and have aero bars retrofitted onto this bike. This is easy, it's just a pair of clip-ons, and it takes 5 minutes to add them. If you add full aero bars, however, you may find that that perfect road bike fit doesn’t work anymore now that you’ve laid your body down on the apparatus that essentially turns your bike into a front recumbent.

The keys to a good fit while on aero bars are few, and easy to grasp. There is now a second angle with which to be concerned, and as is the case with the hip angle above, this second angle is not an angle on a bike—but one formed by your body. Remember that line running from your hip to your shoulder? Now imagine a line from your shoulder to your elbow. This “shoulder angle” formed between your torso and upper arm also ought to be 90 degrees. Achieve this angle and you’ll be comfortable.

(A NOTE ON MEASURING ANGLES: Finding the proper point on your shoulder can make these angles tough to measure, and the points differ depending upon which angle I'm measuring. I find that when measuring the hip angle the line ought to pass from the greater trochanter through the shoulder, and through the collarbone which, while in the aero position, will be in front of the shoulder. But when you're figuring your shoulder angle, the line representing the upper arm ought to pass through the centerline of the arm midway from front to back. The intersection of these two lines represents the apex of the shoulder angle being measured.)

The problem with sticking full tri bars on your “perfectly fit” road race bike is that the bike is too long for these bars or, if you prefer, the clip-ons are too long for the bike. You’ll notice that your shoulder angle is greater than 90 degrees. You’re too stretched out. The solution? Don’t get full aero bars. Buy a shorter bar made just for a road bike position. There are several out there. Cinelli makes two, the Spinaci and the Corna. Profile Design makes a very popular model called the Jammer, and a souped-up version called the Jammer GT.

The good thing about these bars is that they’ll allow you to achieve that 90-degree shoulder angle without changing the fit and set-up on your road bike. The negative is that the armrests aren’t hitting you under your elbows, but under your forearms, almost under your wrists. That is not optimal for a lot of people.

Enter the “tri bike.” This is a bike built around the proposition that you’re starting with a full aero bar, and the geometry of the bike is built around the use of the bar. This bike has a very different geometry than a road race bike, but the “rules” mentioned above still hold. How is that so?

Imagine a picture of a hill climbing specialist riding seated up Mont Ventoux. Stick a straight pin in his bike’s bottom bracket, and rotate the picture forward. His rider position won’t change, if you’re considering the “body angles” spoken of above. If you’re very good with a pair of scissors, cut out just the rider, separating him from his bike. Now rotate him forward around the same axis, leaving his bike in place (as in the photo below-left). You’ll notice his trunk moves forward relative to the bike’s bottom bracket. His back gets flatter. He’s assuming an “aero position.” The only thing we need to do is to place an aero bar underneath his elbows. And this is what a tri bike is—steeper seat angle, lower front end, and a shorter chainstay so as to draw the rear wheel back under the rider’s weight, so that the bike handles appropriately.

How much should you rotate this rider forward? It’s up to you. You can ride with a 73-degree seat angle, typical of a road race bike, more or less. Or you can ride at 80 degrees, common in a full-blown tri bike offering a very aero position. Anywhere in between—anywhere along this continuum—is fine. The steeper your seat angle, the lower your bars can go, that is, the flatter your back can be.

"Why can't I ride my road race bike in a road position AND have full aero bars AND ride with the armrests under my elbows?" you might ask. You can. But then you're likely to have a shoulder angle much greater than 90 degrees, and you'll be uncomfortable. In other words, you can't have it all, so you'll have to pick which features you want, and which you'll choose to live without.

WHICH GEOMETRY STYLE IS RIGHT FOR YOU?

In the beginning of my remarks I wrote, "You must decide which style of geometry is for you." How do you decide that? When a person comes to me for a bike fit, I ask a variety of questions, such as:

• Do you have only one skinny-tired bike, or will you own both a road race bike and a tri-specific-geometry bike?
• Are you intending to road race on this bike, or commute, or do centuries and group rides with road riders?
• Do you intend to spend a lot of time in the aero position, or only be there very occasionally?
• How important is speed to you? (This is not a rhetorical question, there are plenty of people for whom the finish time is not especially relevant).

I will also attempt to ascertain how athletic this person is, and how high the effort level is likely to be during the bike leg of the race. I'll consider the person's morphology—someone who is carrying a lot of extra weight is going to have that weight coming down on the saddle and whatever place on one's anatomy is in contact with the saddle.

Something must be understood about a full-blown aero position. It is most comfortably ridden while under a fair amount of power and effort. Riding an exceptionally easy (perhaps recovery) ride is less pleasing in the aero position than on a road race bike. The easy solution is to have two bikes, which I do. But not everybody does, or at least they don't while still new to the sport. But that does not lessen the realities of which position is best for which style of riding.

Having an an aggressive, aero position for riding to Starbucks for coffee is like commuting to work in the city using a Ferrari. Sports cars are nice, but a Caddy is perhaps better for stop-and-go traffic. How often, and for how long at a stretch, will you be riding with effort in the aero position? That answer to that question will determine where along the continuum from shallow to steep you ought to be.

For this reason, I usually recommend a road race bike as one's first entre into tri-bike ownership. This bike is easy to ride, and the position is accessible to just about anyone. It's a better bike on which to learn click-shifting, clipless pedals, and the beginnings of riding in the aero position. It's a better bike for corning and descending. It may end up being the only style of bike you'll ever own for triathlon. And if you do migrate to a tri-specific bike, you'll still use your road bike for group rides, recovery rides, early season riding, and so forth.

Having said that, there is one other option. Consider the "pink" rider at right. That might be what we could term a "multisport" position, and is just a bit of the way forward in the continuum. One could achieve that position by retrofitting a road bike with short aero bars and moving a few centimeters forward, or by having a slacker-than-usual tri-specific bike. For that person who is looking to spend not too much money and who wants a bike built just for the "multisport" position, however, this category of multisport bike is gaining in popularity, and the Cervelo One, at just under \$1000, is probably the best of the current lot.

The one thing to remember is that shallower-angled road and "multisport" bikes are best ridden with road bars and road-style shifters and brake levers. Choose a handlebar set-up which is appropriate for that point along the aero continuum with which you’re comfortable. Will you be riding in a road race position, at 72 to 75 degrees of seat angle? Choose road race (drop) bars with STI-style shifting and clip-ons. Are you going to be on a steep seat angled rocket? Choose pursuit bars and bar-end shifting.

WHY MUST SEAT ANGLES MATCH FRONT END CONFIGS?

I'm not very patient with bicycle manufacturing companies. They ought to know how to build bikes correctly, and you'd think that if they were going to spend a million dollars or more on a line of bikes for triathletes, they'd take the time to get it right. Unfortunately, it's common to have no one in these companies who actually ride tri bikes; neither do these companies' product managers seek valuable information or guidance during the design the process. If anything, they ask their dealers what they want. This is often the blind leading the blind.

As a result of a process like this, in recent years you've had Cannondale making a tri-geometry bike outfitted with road bars and shorty clip-ons (a no-no) and Giant making a road geometry bike outfitted with pursuit bars, full clip-ons and bar-end shifting. In point of fact, both these companies made one frame, and outfitted their cheap model with road bars, STI and shorty clip-ons, and outfitted the expensive model with the full tri set up. The difference between these companies' approaches is that C'dale chose a steep seat angled tri geometry for the frame behind both these front ends, and Giant chose a road geometry frame.

In the case of C'dale, the proper bike was its expensive model. Since this frame was a full tri geometry frame (78-degrees of seat angle), it ought to ONLY have been outfitted with pursuit/full clip-on/bar-end shifting. It never should've put road bars and a shorty clip-on on this frame (which is what it did with its entry-level model). Thankfully, this sort of mis-spec is in Cannondale's past and it now makes its tri bikes with quite a bit of forethought.

Giant's situation is current, and its approach is the opposite. Its cheaper bike, the TCR Aero II, is a road bike outfitted with road race bars/STI shifting/shorty clip-on. That's a front end that matches the bike's geometry. It's a good bike. But its expensive bike is the TCR Aero I, and it's got a full tri front end. I don't agree with this sort of spec. Happily, it's more or less fixable. Outfit this bike with a forward seat post or an M2Racer Power Module and the bike becomes more usable.

Let's say you were sitting at the dinner table and you were served a hot dog, a baked potato, mustard and sour cream. Those of you who'd put mustard in the baked potato and dip your hot dog into the sour cream ought to put a pursuit bar on your road race bike. For the rest of you, the moral of the story is this: There is nothing wrong with shallow angles, steep angles, road bars with STI, or pursuit bars with bar-end shifting; just make sure you put a front-end on your bike that is compatible with the style of bike you're riding.

The simple way to view it is this: If you're going to ride a traditional geometry, ride the bars that traditionally go with it (road race bars). You contact the bike in three places—where the bike meets your hands, your butt, and your pedals. These three places must be properly spatially related to each other, and they must allow the body to form the two 90-degree angles mentioned in the sections above.

There is a reason that full tri bars don't make sense on a shallow-angled tri bike, and it is related to your shoulder angle. When you're on a properly-fit road bike, and you're riding in a road configuration—73 degrees of seat angle, road bars, STI, etc.—and when your hands are on the hoods, you have something close to that magic 90-degree angle (when you're low and really going hard, with your forearms parallel to the ground). When you put a full tri bar on your bike, the clip-on's extensions reach considerably further forward than the forward protrusion of the hoods. If you extend all the way, and your hands grab the extensions' ends, your shoulder angle is much greater than 90 degrees. You're too stretched out. In order to achieve that 90-degree angle, you'll have to have a shorter clip-on—either a very short size of a full clip-on, or a model of "shorty" clip-on with shorter extensions by design.

Enter the pursuit bar. The idea is to re-create the position formerly inhabited by your hoods, i.e., before you lowered your road race bars to make yourself more aerodynamic. The irony is, people are fain to give up their road bars because they covet their hoods position. But when you lower your bars, you may keep your hoods, but you lose your favored hoods position (and you entirely lose your drops position). The only way to maintain your hoods position is to dump the hoods, and the bars on which they're mounted, and go to a flat pursuit bar. Then you'll regain (something close to) your hoods position.

I'm often asked about the utility of having STI shifters on a pursuit bar. I don't like this, because of the technical way a forward tri position ought to be ridden. I'll write about this in more detail in a future installment, but for now I'll reiterate that this is a position which must be ridden at a high cadence—no lagging, or mashing. The need to shift often is paramount, and having the shifters where your hands are is critical.

There are three ways to determine saddle height. Method Three is the subjective method—adjust it until it feels right. This is really the ultimate eventual way. After you utilize objective methods One and Two, you'll always come 'round to Method Three. But you shouldn't start there and besides, your ability to correctly apply Method Three depends upon whether you're body aware and untuitive, and some people are just body-deaf (or whatever the body-awareness-analog is to "tone-deaf").

This leads us back to the objective methods. Method One is to use a multiplier of one's inseam. Stand on the ground, straight-legged, and place a book up into your crotch, about where you figure the saddle will rest. measure this distance to the ground. Multiply this by .885. Some people use .883. Personally, I don't like this method, because of the imprecision of where the crotch actually is; and where to measure to on the saddle's top. I also think that for steep seat-angled tri bike riding the saddle ought to be slightly higher than for road riding. This remains, however, the predominant way to measure saddle height.

Method Two is to consider the knee angle when the pedal is in its lowest position. But first there are a few things I need to make clear. There are two places on the foot to which you're going to measure. When you're determining the location of the bottom of the pedal stroke, this is measured to the pedal axle, and while the differences are minute, and for the purposes of measuring knee angle, I don't like to consider 6 O'Clock the bottom of the pedal stroke. I rather prefer it to be that point where the crank arm is parallel to the line drawn up to the greater trochanter (i.e., more or less parallel to the seat post). If you consider the red line in the adjacent diagram, this is the position in which the knee angle ought to be measured.

But once your leg is in this extended position, you'll now start measuring to a different area. When determining knee angle you're measuring to the maleolus.

Using the bony protrusion of the outside of the knee as the angle's apex, draw a line to the greater trochanter (bony protrusion of the hip) and to the maleolus (bony protrusion of the ankle). The angle formed ought to be either 145-150 degrees, or 150-155 degrees, depending on whom you talk to. For road riding, I think 150 degrees sounds pretty good. For tri bike riding I like it closer to 153-155 degrees. Perhaps increasing the angle one degree might be roughly equivalent to increasing the saddle height by one millimeter, though it's going to differ depending on the height of the rider.

The tricky parts of calculating saddle height by Method Two are: 1) you really need a second person to do this; and 2) your pedaling technique is going to effect this—if the aspect of your ankle is not correct during the pedal stroke it can cause your seat height measure to be off. If, for example, you're pedaling too much with a "toes down" aspect—if you have to stretch to reach your pedals—you might think your seat height is correct by virtue of your knee ankle when in actuality your seat would be too high.

On the other hand, the nice thing about this method is that it takes into consideration the height of your cycling shoe, pedal and cleat, where you sit on the saddle, any shims that correct for leg length discrepancy, and your crank length. It also takes into consideration any influence exerted by your pedaling technique. So I guess I like this method better.

What do I mean by "influence exerted by your pedaling technique?" I tend to ride with a fair amount of "heel drop." I also seem to read that heel drop, or lack thereof, is a matter of personal preference. Fair enough. But whatever your preference, it's going to make a difference in your saddle height. If my heel is dropped more than yours at the bottom of the pedal stroke my saddle needs to be slightly lower in order to maintain this 150-155 degree knee bend.

What influences heel drop? Your power application throughout the pedal stroke, your desire to utilize your calf muscles—a somewhat insignificant muscle group in pedaling, but of some utility—and your cleat mount (the more forward your cleat, the more you can recruit your calf muscles).

DETERMINING WHICH POSITION IS BEST

Now we get to the meat of it. This is the most difficult part, and if you're a bike fitter it's the part requiring the most skill, in my view. I don't mean the act of executing a proper tri bike fit on, say, Tim DeBoom or Peter Reid. That's easy. That takes 20 minutes, or ought to. The skill comes in determining whether a subject ought to be positioned like Peter Reid, or on a road race bike with STI and shorty clip-ons, or somewhere in the middle. And if it's in the middle, where in the middle?

T
he hard part is figuring out just how aggressive one's position ought to be and can be. The devil of it is, you can be positioned at 74 degrees of seat angle, 76 degrees, 78 degrees, and at 80 degrees, and in each of those positions you might feel great. If you are positioned too shallow, might you've gone faster if you were positioned more steeply? If you're set up steeply, what will you feel like after three hours in the saddle? I believe the art and science of tri bike fitting ought to be light on the art and heavy on the science—but if there's a place for art, this is it.

The goal is to get you as close to 80 degrees of seat angle as possible. The reasons for this are two. There is the lower metabolic cost associated with riding further forward, as demonstrated by those in the scientific community (and which we've written about elsewhere). By "lower metabilic cost" I mean less recruitment of fast twitch fibers during the pedal stroke, leading to a lower rate of glycogen consumption at a given power output (fast twitch fibers consume glycogen at a rate 50 percent greater than do slow twitch fibers). I admit that it takes a short leap to come to the conclusion at which I've arrived—a tieing together of studies to make a point. My full explanation will be found by following the link above.

Then there is the aerodynamic benefit associated with being able to ride lower in front, which is linked with riding forward (it's hard to ride low if you don't move forward). This requires another leap of faith. It's my assumption that by having one's handlebars lower rather than higher that the result will be a position exhibiting better aerodynamics. Surprisingly, even this is not universally agreed upon. But we'll assume this as axiomatic, and for those who don't believe that lower in front almost always means a lower coefficient of drag, we'll just have to agree to disagree.

Though a lower front end might mean lower drag, it doesn't necessarily mean a lower finish time. There are four mitigators, and each of these mitigators serves to cause one to sit further back than 80 degrees. The major one is comfort. If you can't maintain the position comfortably for the duration of your race, what good is it? In this case it's better to be more rearward. This will mean you'll also be a little higher in front. You'll sacrifice a little bit of aerodynamics. So be it. You'll be better off in the long run (pun intended).

The second mitigator is the "M-factor" and "M" is for Mystery. Yes, Peter Reid, Cameron Brown and Tim DeBoom ride quite steeply. But Cameron Widoff doesn't. Yes, Craig Walton rides steeply—very steep, if you consider not just his bike set up, but where he rides on top of the saddle—yet his countryman Chris McCormack doesn't. Natascha Badmann and Paula Newby-Fraser ride steeply, but Heather Gollnick doesn't. While three-fourths of the world's best triathletes ride steeply, 20-25 percent don't. Why? Is it because they don't know any better, or because they just haven't been set up in a correct steep position?

I don't think this gives them enough credit. I rather suspect it has something to do with levers and musculature. I don't believe riding with a steeper seat angle gives you more power at the same heart rate (a claim I've seen), but I do believe it gives you equivalent power and heart rates while spreading the work around to both anterior and posterior thigh musculature during the pedal stroke. Let me use an analogy...

Imagine a company with too few workers and a lot of work to perform. Some of their employees have to work overtime, and the company must pay time-and-a-half. If they hire a few more employees, the work gets spread around, and the company doesn't have to pay overtime. Let's say, however, that it's the best, strongest workers who're getting overtime pay. Do you hire more workers or pay overtime to the strongest workers you've got? This is the dilemma. Most triathletes find that more employees is the better solution, and as a result everyone on the job has more energy for happy hour after the evening whistle ("happy hour" being the "run" in my metaphor). For some athletes, though, I think evening the work throughout the thigh muscles isn't playing to their strengths. I don't entirely know why.

The third and fourth mitigators have nothing to do with anyone reading this, but I'll mention them anyway, because the subject comes up. There are two reasons Lance Armstrong doesn't ride with a steep seat angle. The first one is, he'll get kicked out of the Tour de France if he does. The rules won't allow it. If your racing was governed by these rules, believe me, you would know it. Only bike racers fall under these rules, and even then not one percent of the bike races in the U.S. are subject to UCI rules. But even if the rules did allow Lance to ride more forward in the time trial, I don't know that he would. There is a risk associated with changing one's riding style for one or two days sandwiched in between the 20-odd days of a grand tour. I suspect that's a risk some grand tour riders are unwilling to take. Keep two other things in mind when using Lance's riding position as a model. First, he's not running off the bike. Second, in his "former life" he did win two national triathlon championships on bikes I provided him—both 80-degree seat angled bikes.

Contemplate the diagrams above, and realize that anywhere along the continuum from 74 degrees to 82 degrees of seat angle are fine. However, there are rules you must obey. First, those two 90-degree angles written of above must be preserved. Second, the more rearward you are the more appropriate are road bars, STI, and a shorter clip-on. The more forward you are, the more pursuit bars and bar-end shifting start to make sense.

Where ought you to be along this continuum? All things equal, the younger, leaner, fitter and lither you are, the more forward you'll want to ride. Also, the shorter the race the more you'll probably want to be forward. If you ride with lesser effort, if you carry more weight, if you're older, if you race a longer distance, and if you're more of a mesomorph (strong, muscly-type) the more you're likely to tend toward a position back from 80 degrees.

Where you eventually ought to end up depends on your subconscious tendencies while riding. Do you always seem to be scooting forward in the saddle? Are you sure it isn't because you're too stretched out, and you're subconsciously trying to "achieve" that 90-degree angle between your upper arm and torso? If you're riding on the saddle's nose in spite of having a proper cockpit distance, you're probably positioned too shallow. Are you always pushing yourself back in the saddle? Are you sure it's not because your saddle's nose is tilting down (a bad idea, by the way), causing you to have to push yourself back because you're sliding forward? If you're almost always sitting on the rear of a level saddle, perhaps you're too far forward. Are you frequently out of the aero position? Again, you're probably too low in front and too far forward—while it's a position that might feel good for short spurts, if you can't maintain it for the duration of the ride, you're just too aggressively set up.

A NEW FORMULA FOR SLACKER-ANGLED ARMREST DROP?

I have a formula for armrest drop, and it is this:

This formula causes a lot of hand wringing, because people just read it and try to conform to it, without following the "rules" that are associated with it. But first, I'll explain it.

Distance "C" is what we're looking for, and it is the distance in height (in a vertical plane) between the saddle and the armrests. If you were to drop a line from the top of the saddle to the ground, and measure it, and then do the same with the armrests, the difference between these two numbers would be the difference in height between the saddle and the armrests. The easiest way to measure it, I think, is to lay one end of a carpenter's level on the saddle, and angle the level over one of the armrests. With the bubble in the middle of the level (i.e., with the level parallel to the ground), measure from the bottom of the level to the top of the armrest with a ruler.

The assumption is that we've already got the seat height established, via the guidelines in a chapter above. We've also got the "cockpit distance" more or less established, that is, the distance from the nose of the saddle to the ends of the clip-ons, because that distance is whatever it needs to be in order for our upper arm and torso to achieve a 90-degree angle. You've then raised/lowered your bars so that your "hip angle" achieves a 90-degree angle, or perhaps 95-degrees, and by virtue of that we don't really even need a formula for armrest drop, because the drop is whatever it needs to be in order to achieve the proper hip angle, right? So, why do we even have a formula for armrest drop?

Only as a double-check. If, after you've positioned yourself properly, you plug your saddle height into the formula and you get a number WAY off from the range indicated by the formula, then you've got to ask yourself why. Perhaps there is a perfectly appropriate answer. Either way, that's what the formula's for—it's just a double-check.

But there are rules and assumptions:

• This formula assumes that you're a very fit, well-trained athlete in mid-season form.

• This formula applies to a position all the way forward along the continuum, which for me means something in the order of 80 degrees of relative seat angle. If you're positioned at 76 degrees and you try to apply the formula above, you might find that the position is too aggressive and—guess what?—you'd be right. You don't have a steep enough angle to justify a drop of that degree.

Here's how it would work, and I'll use myself as an example—I'll present the formula again below for reference.

I ride with about 79cm of seat height (distance "D" in the formula above). That quantity, squared, times .005, equals 31.2. Subtract 79 X .2 (which totals 15.8) and you get 15.4. Subtract 1.5 and that equals 13.9 (we'll call it 14)—and realize all these calcs are in cms. The fudge factor is 1.5cm in either direction, so my armrest drop could range anywhere from 12.5cm to 15.5cm. It is in fact about 13.5cm.

I admit, however, to having a more aggressive seat angle than most (I ride with 80°). What about those who'd like to ride at perhaps 78°, or 76°? What ought their drop be? While I'm not convinced of the utility of this, I'm working with a coefficient-based adaptation of the formula above, where ".2" above increases by 075 for each degree shallower than 80° you'd ride. So, if you rode at 79° the product would be (.2075D), and if you rode at 78° it would be (.215D). Here's the calc for someone riding at 77°:

In this case, if I were to use myself as an example (and if I haven't made a mistake) the drop for me at 77° of seat angle would be about 12cm, and the range would then be 10.5cm to 13.5cm. In other words, if I slackened my seat angle by 3°, I'd probably have to raise my bars about 2cm, more or less. You can see why this would be the case. If I don't raise my bars when I slacken my seat angle, my hip angle will become too acute.

Perhaps adding this whistle to my formula will prove efficacious, though it's too early to tell. I hope, at least, that you see the point, which is that you can't take any of these features—seat angle, armrest drop, clip-on length, base bar type—and consider them in a vacuum. They all must make sense as a construct. I hear, every now and then from retailers, that my formula represents a front-end drop that is too low for the bulk of their customers. Maybe it's because the rest of the fit is bad. Or maybe it's because it's being applied to customers who're being set up at 76 degrees of seat angle. If one takes into consideration the limitations of this formula in its raw form, then perhaps it appears less formidable.

HOW TRI-SPECIFIC GEOMETRIES MUST BE RIDDEN

This topic is not specific to tri bike fit, strictly speaking, but it deserves mention. If your retailer sent you and your mate out the door on a tandem, he'd be well advised to give you a tip or two if you were tandem virgins. Likewise, it ought to be pointed out that your riding experience on a tri-specific bike is not going to be 100 percent positive if you don't take advantage of the strengths of this bike.

By "this bike" realize what I'm going to present below assumes that you're on a tri-geometry bike, riding with a seat angle of 77 degrees to 81 degrees. The shallower you are—76, 75, 74-degrees—the less this section refers to you. In fact, if you're riding below 75 degrees of seat angle it doesn't refer to you at all.

There are just three things to remember, and these points ought to govern your tri-geometry riding.

This is a position which optimizes the use of lay-down, tri-specific handlebars. Any time you're in the aero position, you're on a better bike than a road race bike. Whenever you're out of this position, you'd have been better off on a road race bike. Therefore, you better like your position, and be prepared to be in it almost all the time.

Imagine skating around an ice rink. What is your intent? To skate quickly, and perhaps race? A nice, long pair of speed skates is made for the purpose. But what if you want to just knock around with the guys occasionally? Jump into a hockey game now and then? Do a few pirouettes? Or just tool around at an easy clip? Clack skates aren't made for that purpose, and you'll find them unwieldy. Likewise, a steep tri-geometry bike isn't made for much else other than going hard at it while in the aero position. Consider this before you adopt this position.

Because of this, there are certain positions that make sense and others that don't. Besides being in the aero position, there is also an intermediate position that I sometimes adopt, something not unlike the "multisport" position described above. I call it a "choke up" position, and it's adopted by moving very slightly rearward on the saddle, choking up a few inches on the extensions, and sitting slightly up. While in this position you'll be able to generate a bit more peak power, and you might benefit from getting out of the full aero position now and then.

Riding entirely out of the saddle is also a usable position, and riding in the pursuit position is fine for descending and cornering. What I often see, but do not at all like, is a sitting-up position with the hands on the armrest pads while seated climbing. The hip angle is now too obtuse, and this is a low-cadence, low-power position. Better to climb either in the aero position, perhaps in the choke-up position, or out of the saddle. Never sitting entirely up.

This style of riding trades high-torque riding for even-powered riding. You won't be able to generate the sort of peak torque in the aero position that you will while in the road position. Your overall power will be the same, but your ability to mash a low cadence, or to accelerate, will be compromised. Therefore, it is imperitive to keep one's cadence up, probably in the 90-100rpm range. It's quite acceptable to climb while in the aero position. You'll be surprised how fast you can climb, although you might not think you're climbing fast unless you're comparing yourself to others of equivalent ability, or your own previous times recorded up a fixed ascent. But you will be able to climb fast. This assumes, though, that you really do keep your cadence up, and this is a discipline that is hard to learn.

If you think about this, a couple of equipment changes appear rational. First, if it's so important to keep your cadence up, it's important to keep your shifters close to your hands. Therefore, bar-end shifting is a very good idea for steep-geometry riding. Secondly, make sure you've got the appropriate gears at your disposal. I'm usually riding 53X39 and 12-27 on my 700c-wheeled bike. On a hilly course I've been in my 39-27, spinning up a hill in the aero position, next to a person climbing out of the saddle in his big chain ring. If that gentleman outruns me it won't be because he was a wiser tactical rider.

"Why?" you might ask, "is it preferable to trade in a high-torque position (riding a 73-degree seat angle bike) for a low-torque position?" Because you don't want to recruit fast-twitch fibers during the bike ride. You don't want to use muscles that burn glycogen at a higher rate. This issue is what separates road riders from triathletes. This is why triathlon is its own sport, and why you can't necessarily emulate what you see in the grand tours, even the grand tour time trials. If you don't have to run off the bike you don't have to worry about the metabolic cost of your bike ride. If you're reading this, it's likely that running is in your future.

This position is most comfortably ridden under effort. The more you're rotated forward and low in front, the more you're riding on points on your trunk that don't have much padding. When you're riding in this position under very low effort, the weight is transfered off the pedals and onto the saddle. Therefore—though it sounds counter-intuitive—the lesser your effort level while in the aero position, the less comfortable your crotch. This doesn't mean you can't ride your tri bike during easy, recovery rides. It just means it's not optimized for that. If you have a road race bike, this is usually a better choice for recovery riding.

Don't take this to mean that a steep-geometry position is unusable for all kinds of riding. It's usable, just not optimal, for all kinds of riding. Likewise, road bikes aren't optimal for all kinds of riding, but they're often used in triathlons anyway. It's just a question of what sort of riding is most important to you, and then adopting not only the most appropriate bike position, but the tactical and technical riding styles that dovetail with that position. When I hear, "I tried a steep-angled bike but I found I just couldn't generate enough power," I find that in most cases it was because the rider didn't understand how steep geometry bikes need to be ridden. He rode his tri bike around town at 70rpms. Of course he couldn't generate enough power.

HOW DO YOU CHOOSE A BIKE AND HANDLEBARS?

If you were in the market for bike for road racing, things would be simpler. Most road bikes are built inside fairly narrow parameters. There is almost no road bike in your size that you can't easily make fit.

Not so in triathlon, where a wide variety of options exist. There are "tri bikes" with 74-degree seat angles, and with 80-degree angles. At 6'2" in height a tri bike in "my size" might have a 60cm top tube or a 54cm top tube. Certain bikes styled as tri bikes are in fact nothing more than road bikes marketed to triathletes. How does one go about choosing? There are some guidelines that might help.

You can make any bike fit. I'm reminded of an Arnold Swarzenneger movie in which he had to rip out the seat of a small car he was "borrowing" in order to fit inside it. Better if he just had to adjust the seat back a bit. The trick is to find the bike that takes the least amount of jury-rigging to make fit.

Your first duty is to figure out which position is going to work for you—where along the continuum (spoken above) you'll need to be. There's nothing wrong with being all the way back, i.e., to ride in a road race position. You'll have a difficult time riding comfortably with a full tri bar, however. Better to get a shortie bar.

At this point I shall digress slightly, and gently scold many of you who'll read this. As I write this I'm fresh back from the Wildflower Triathlon, where I had the opportunity to ride past perhaps a couple of hundred athletes. These are good athletes. You don't enter the half-Ironman version of this race unless you're reasonably fit. There were four things I noticed: that a great number were on traditional road bikes in a road configuration; that the overwhelming majority were riding with road bars and clip-ons; that most had full tri bars (not shorty bars); and that a good half of all the riders were out of the aero position and on their hoods, even though riding on the flat roads.

The greatest number of athletes I encountered were riding on the "backstretch" of this course, the straight section from mile-20 to mile-35. This entire stretch was ridden into a headwind. There was every reason to be in the aero position and no reason not to be. Why were so many riders not where they ought to have been?

My view is that after 30 or so miles of hard riding it was just no longer possible to sustain an uncomfortable aero position. Riders couldn't take it any longer.

Yet it's these same riders who complain that they, "ride a road bike because it's to uncomfortable to ride a tri bike for 56 miles." Notwithstanding that I, with my 80-degree tri bike, was out of the aero position for perhaps 20 seconds during the entire ride, I'll stipulate to that point. Maybe a road bike was a better bet for all those people. But heavens, it can't be right if you're not able to spend 25 or 30 miles in the aero position without abandoning it, right?

To that end, I'll share a letter I recently received from a reader, who writes the following:

"If you have time I have a question for you. I just read your update to the Tri Bike Fit. I seemed to understand the bike fit article better than when I read your original article. I'm riding a Litespeed Saber. I had what I believed was a professional fit to my bike. It cost a professional amount, \$200, but I'm not sure of the benefit to me as a triathlete. The fitter, [I'll omit the name, it was a well-known tri bike fit professional], had my seat as far back as possible on an already set-back Easton Carbon seat post. His rationale was that the plumb line from behind my knee cap was too far forward of the pedal spindle when at the 3 and 9 o'clock positions. His goal for my knee angle was 140 - 145 degrees. With his setup I could not ride in the aero position more than a few minutes. I was uncomfortable. I kept sitting up and riding on the bullhorns. This totally negated the benefit of my tri bike. I moved the seat forward after a couple of weeks and can ride in the aero position as long as the terrain allows. After reading your article, I move my seat forward to be in line with my seat tube and raised the seat to achieve 153 degrees in my knee angle. Now finally to my question. Do you concern yourself with knee position over the pedal spindle? If so, do you use center mass of the knee joint, behind the knee cap, or the front of the knee cap?

"Thanks for your time and the updated article. It has provided more useful info than the fitting I received."

This person could've used a laid-back position, but not with the full aero bar at its full extension, as the bike was originally spec'd. At least, if you're going to choose a road bike and road position, choose an aero bar that allows you to maintain that 90-degree shoulder angle. My favorite has been the Profile Design Jammer GT, but there are others, such as a couple of designs shown here by Deda Elementi (I'd shorten the bar above quite a bit more than the photo suggests, and I may or may not even use the armrests—I might just wrap the tops with a couple of rolls of bar tape). I don't think the perfect aero position bar for road position riding has yet been invented, but there are some that make a decent attempt—examples would be these by Deda, the Profile Design bars, and Cinelli's Spinaci and Spinacissimi.

Should you desire a steeper-angled bike, you can either choose a bike that is already sufficiently steep, or a shallower one might work if it's also long in the cockpit. I, for example, like my bikes steep, like 80 or 81 degrees. I also like them low in front, and short in the cockpit, like 55cm or 56cm of top tube (my road race bikes have 60cm of top tube). I can make a 76- or 77-degree bike work, however, if it's got 58cm or 59cm of top tube. Certain QR and Felt bikes are good for me in this respect. By the time I move the saddle forward (by any number of means) the bike is both steep and short enough for my liking.

This assumes, though, that the front end is low enough. It's hard for me to get my bars low enough on a 700c-wheeled bike if the head tube is longer than 13cm or 14cm. I can live with a 15cm head tube if its got an integrated headset, because now there is 15mm to 20mm worth of headset "stack" that I don't have to worry about, because the headset paraphernalia is inside the head tube.

So what do I do if I want to ride an Aegis Trident in my size, which has 17.5cm of head tube and a non-integrated headset? It's hard to get my bars low enough, and I'm pretty well stuck unless I also decide to ride with a lower-profile aero bar. I can ride a Trident quite nicely if I've got a HED aerobar or a VisionTech—assuming I'm not using any armrest riser kits, or Vision's plush aftermarket armrests that raise the elbow position quite high above the centerline of the base bar.

Conversely, if you're thinking of retrofitting your existing bike with one of these slick aftermarket bars, consider what aerobar you're currenty riding. A Profile Aerolite has armrests that sit about 7cm above the centerline of the pursuit bar, and other Profile bars, and Syntace bars, have about 6cm of rise. The HED aero bar's pads sit 2.5cm above the pursuit bar's centerline. So, if you take off your Profile Aerolite and replace it with the HED, your arms are going to be sitting 3.5cm lower to the ground (all other things equal). You'll need a new stem, or something, if you want to achieve your previous position.

This might seem complicated, but it's not. It's just stuff you need to keep track of. With road race riding, there are a lot of road bars out there, but from a positioning perspective a bar's a bar. With tri bars, as with tri bikes, there are wide variations in position across every axis. When you're considering a bike, where along the continuum is your desired position? Make sure the bike, and the aero bars, allow you to achieve the 90-degree angles written of above while in this position.