Hallmarks of a good tri bike fitter
12.10.04 by Dan Empfield

When I used to be the big cheese at a popular triathlon product manufacturer we did a few things that the other companies didn’t. We took our show on the road, literally, and the Quintana Roo Traveling Road Show was always a well-attended event, wherever in America we landed. We’d bring in aerodynamic experts, nutritional gurus, but the line for bike fitting was always long. We’d set a half-dozen fit bikes up in a row, and people would stand in line waiting as if for the only six massage tables at the finish line of the Hawaiian Ironman.

I may be dumb, but I'm no fool. It occurred to me then and it occurs to me now that the biggest problem facing triathletes is how they are positioned atop their bikes, and there is now no shortage of people charging anything from $50 to $500 to professionally execute your bike fit.

Some—well, many—of these professional bike fitters are truly horrible. Even some that charge near the top end of the spectrum. No, there is no foolproof way to know who does it with knowledge and talent, and who does it badly. But there are some good earmarks upon which you can rely. There are a dozen, perhaps fifteen, parameters that separate the varsity from the jayvees. In my opinion, the best tri bike fitters have the following qualities. One word in advance: When I write the word HE I mean male or female. There are several really good female tri bike fitters out there that I can vouch for personally, added to the number of good ones of which I'm not yet aware.


Yes, I run a sort of school for hands-on bike shop owners and their managers, teaching them how to fit a triathlete to his or her bike. Does the label "F.I.S.T. Certified" mean you're going to have a competent person executing your tri bike fit? Maybe, maybe not. Practice makes perfect, and if your prospective tri bike fitter doesn't perform at least 25 full-blown fits a year on triathletes I would think twice. Best is someone whose regular duties include tri bike fits—somebody who is a tri bike fitter first, or second, or third, and not a tri bike fitter only upon pain of death, when there is no way to get around it.


There are tri bike fitters who do not entirely agree with me but who have thought things through, and you can easily tell this when you ask him some tough questions and then listen for the answer. Read what's on these Slowtwitch pages concerning tri bike fit, and then ask your prospective fit specialist some probing questions. Whether or not this person comes up with the same answer I would is less material than whether he knows the subject matter.


There is, of course, the letters after your name. If someone holds a master's degree in exercise physiology, that's meaningful. Probably even more so are the other professional designations, like F.I.S.T. Certified, Serotta bike fit school graduate, someone who has been through the curriculum offered by New England Cycling Academy, and even someone who has been through the Barnett School for bike mechanics. Such designations mean both the subject matter has been imparted, and that the person takes this seriously enough to have invested financially in the process.


It's hard to execute a good bike fit without a good fit bike, or "adjustable position simulator" if you prefer. Not impossible, but harder. Better yet is a fit simulator with a computerized load generator, like one made by Computrainer. Not all adjustable positioners are good for triathlon. The one made by Bikefitting, for example, has a couple of problems associated with it, at least when I'm the fitter. The seat angle is changed by rotating the seat tube around the bottom bracket. This works nicely for road cyclists, because it keeps the seat height constant. However, saddle tilt is much more critical for triathletes, and when you have that saddle tilted appropriately you don't want to have to change the tilt every time you change the seat angle. Easier to readjust the saddle height than the saddle tilt. I do have a Bikefitting bike, and I have a completely horizontal fore/aft seat angle simulator (illustrated above) added on, and this fixes the problem (I had Ves Mandaric of Yaqui make this for me; anybody out there doing bike fits for triathlon on a Bikefitting unit, give him a call if you'd like him to build you one). But, the Bikefitting bike also has a problem with its front end—it's hard to adjust it low enough for triathlon. So, I've had to make adjustments to that too, and it's now one of three fit bikes I own that work well for triathlon bike fits (the stock Bikefitting bike is great for road bike fits, these adjustments of which I write make it—for me—a more appropriate simulator for tri). Whatever the methodology used by your prospective fitter, it should just be apparent to you that his investment in tools means tri bike fit is a primary element of his business.


In my opinion, the best fitters are also avid users. It's hard to understand what a triathlete goes through if you haven't spent a lot of hours riding bikes in the aero position. There were a lot of things I came up with as a bike maker back, say, fifteen years ago: the use of pursuit bars as base bars; the need for flat pursuit bars (in the days before low-profile armrests); plug-in brake levers; bar-end shifting; steep seat angles; and on and on. These were obvious necessities, and were all first seen (to the best of my recollection) on QR's bikes. But they weren't strokes of genius. They were obvious and intuitive needs, and ended up on QR's bikes because I was just about the only bike manufacturer who was also an avid, reasonably high-level, triathlete. Still today there are few bike companies of any size whose principals actually regularly ride bikes with aero bars. That's why there are quite a few ill-spec'd and ill-designed bikes for sale. Those making the bikes aren't riding them. Likewise, if your tri bike fit specialist doesn't have some significant history of riding tri bikes, there are intuitive things he just won't know. It's a more important part of his or her education as a bike fitter than any other school or class one might attend.


When Syntace moved its distribution from Southern California to the Midwest during the past year it wanted to clear out its warehouse prior to moving east. I took the opportunity to pick up about 40 or 50 Megaforce stems (my personal favorite stem) in every size offered. Now, I don't even do bike fits anymore. Yet, it's just a weird anal thing for me, I always have multiples of sizes of every stem, base bar, aero bar, different saddles, seat posts in various configurations (set back, straight, forward, in various lengths), and seat pads. If I have all this stuff and I don't even do bike fits, it's certainly necessary for someone who does do this for a living. If such a person doesn't have available every conceivable option—stems in various pitches from 5cm to 13.5cm in 10mm or 15mm increments, for example—the question I'd ask is, "Why not?"


There is a school of thought in the industry that certain well-respected bike fit specialists espouse. Included in this movement is a set of doctrines that include two surprising assertions: that there is no scientific basis for the utility of steep seat angles, and that there is no proven basis for the use of aero tubes in bikes (and, one assumes, the use of aero equipment at all) below 30 mph. When I say this is surprising it’s because the people I know who espouse this idea tend to be agreeable to the use of science to support a set of views.

Perhaps not so surprising (because the world is full of proponents of one thing or another that use science selectively to endorse a preconceived point of view), these views appear at face value to stand in front of and atop an economic underpinning. If one hears that science is "inconclusive" on the subject of global warming, overfishing, or the incidence of side effects associated with a certain drug, you might occasionally notice that such a find of scientifically generated ambivalence appears coupled with an economic expediency. And, it turns out that those who espouse the views on round tubes often only sell bikes made by manufacturers that make substantially round-tubed bikes.

Maybe this is a coincidence. If so, it’s a curious and convenient one. When one considers the fact that as of this writing every, not most—or many, or some, or almost every—but 100-percent (to my knowledge) of all scientific studies published in respected peer reviewed journals speak to the efficacy of steep seat angles over shallow, then it is hard to justify the assertion that no scientific evidence exists for this. One might assert that all these studies are flawed, but it seems to me there must be some PhD out there somewhere who can come up with a bit of legitimately generated evidence to support a contrary view.

As to frame aerodynamics, I am the first to concede that features associated with wind cheating must stand in order behind more important elements of frame design. Certainly a decade ago many of the "aero" frames and tubesets were not aero, and were little better, no better, or even worse than round-tubed bikes. But time marches on. Early aero tubes were sometimes so flexible in the lateral plane that getting out of the saddle meant rear tires rubbing on chainstays, left then right, then left and right. It used to be that the minor diameter of aero down tubes were as wide as 45mm, and aspect ratios were much less than 3:1. Certainly it's only fairly recently that truly aerodynamic frames have reached down in price to the point where the average person has a shot at affording one. Finally, it’s also quite recent that such well-conceived frames have been made in geometries appropriate for truly good aero positions. Consider how "roadies" like Ivan Basso and Bobby Julich look on their Cervelo P3 time trial bikes. Even the average triathlete can see that these positions are outstanding, where the same athletes a year or two ago rode positions more apparently awkward. The bikes fit these riders like gloves, because the bikes sit appropriately displaced underneath the riders. Not only Cervelos are made like this, but today’s riders who have QRs, Litespeeds, Felts, and who might ride an Elite, a Guru, a Kestrel, a Kuota, or any number of makes have nice-fitting bikes that contain legitimately aero features.

Bikes must first do what bikes do. When an aero frame ceases to properly display an aversion to lateral flex, speed wobble, proper handling and geometry, when you can’t route the cables, or the cables don’t easily glide, when a frame is not substantially strong and safe, when it can’t accept water bottles or other necessary peripherals (even if such items are only used during training), when the frame is not straight and true, if there is a huge weight penalty, then aero tubes are more trouble than they’re worth. However, I've seen the results of a lot of wind tunnel tests. I've physically been at tunnels, and seen the numbers on these scales at various wind speeds. When a frame plus its fork weighs less than five pounds, and it’s acceptably stiff and straight and true, when it can be easily assembled and maintained, and the mechanical and ergonomic features are there, when the frame is geometrically appropriate, then one puts his reputation at risk when concocting a novel theory of aerodynamics that has no basis in demonstrable fact whatsoever.

When such a paradigm exists in the world of religion—people who, as a movement, espouse a sort of truth that omits or disregards or explains away every element of established and agreed-upon fact—it's considered a cult. In my view, it's best to beware of cults wherever they appear, even in the world of professional bike fitting.


Specifically this relates to products that are tri-bike-fit specific. Should you decide to consider a custom bike, for example, the aero bars you select will have a huge impact on the geometry of the bike. Deciding on a VisionTech or Hed aero bar means your armrests will sit several centimeters lower than if you choose a Syntace aero bar. This means your custom bike would need a head tube several centimeters greater in length. Likewise, there are really big differences in the geometries of various tri bikes. Saddles vary widely as to their utility for aero position riding. Your bike fit pro will need to be up on all this. More than once I've seen custom bikes built with very tall head tubes only because the rider (I suspect) was not given a choice of good saddles to try, and ended up spending many thousands on a custom bike that alleviated saddle pain by raising the subject so high in front as to keep his or her nether regions from contacting the saddle. Instead of a $6000 bike, however, perhaps a $120 saddle would've fixed the problem. "Will you talk to me about elevation differences between the different aero bars when I come for a bike fit?" you might ask. If your prospective bike fit professional doesn't know what you are talking about, well, maybe you should pass this opportunity by.


There is still no bulletproof way to calculate a triathlete's points in space and quickly, precisely determine what frame geometry is needed. This is because tri bikes have the aero bar atop the base bar, and this adds exponential problems. That said, the truly professional tri bike fitter will be able to explain to you a scheme for accurately taking "points in space" (points where your saddle and aero bars must be in relation to the bottom bracket) and translating them to points on a bike, and thence deduce the needed geometry for a frame.


It might seem funny that I'm writing this. That's because my own views of tri bike fit are either misunderstood or (sez the paranoid devil sitting on my shoulder) purposely misrepresented. If anyone says to you, "Steep is bad for triathletes," or, conversely, "Shallow is bad for triathletes," I'd consider steering clear. There are reasons why so many athletes are found riding all over the map as regards seat angles and configurations. Part of the reason is that they don't know where on the bike to ride. But part of the reason is that there is a wide range of acceptable positions, and one's degree of athleticism, goals, morphology and pocketbook will determine the appropriate set-up. The key element isn't rider flexibility, it's bike fitter flexibility.


This is a tough one, I know, because this alone excludes a lot of prospective bike fitters from consideration. If I was to ask all the road product managers of all the bike companies today what "trail" is, probably half would be able to easily answer the question. If those designing your bikes don't know the answer, how likely is it your tri bike fitter will know? Especially if his background is in life sciences, not bicycle engineering? Yet, I'm sorry, but I think the basic knowledge of how a frame functions is pretty important. Knowledge of a bike's front/center, chainstay, wheelbase, bottom bracket drop, head angle, fork offset, in other words everything that matters when you want to make a well-fitting bike also a nice-handling bike, is necessary. This is especially true if you're having this person design you a custom bike. "No, such knowledge is not necessary," one might argue. "The bike fitter generates the fit parameters, the bike manufacturer decides on the geometry." Assuming the bike company understands the dynamic of how a tri bike ought to handle is a big leap of faith. I'd rather go to a fitter who truly understands the process from start to finish, and can explain it to you in terms you can understand and that make sense.

These are probably not the only skills your typical first-class tri bike fit specialist will have. But they are the mandatory ones if what you want is a crackerjack expert. How many such people exist in North America? I don't know. Not as many as would be nice. So, choose wisely. You don't need to be a knowledgable, wise bike fitter, but you do need to be knowledgable and wise when choosing one.