Great question. And here's the great answer: Nothing will shave more time off your bike split than an aero, comfortable position. There was a great article on Cervelo's site about bicycle aerodynamics. The quick summary is that for a 40k race, an aero position (ideally a horizontal torso) can save you 6 minutes, while aero wheels might save 1-2 minutes and an aero frame 1 minute (note that these are not all additive - read this article if you want to know more). Clearly, a good aero fit is the most cost-effective way to speed up your bike split.

Now, you probably had some type of bike fit at the local bike shop when you bought your bike. If you ride a road bike in a standard road position, obtaining a halfway decent fit is relatively straight forward. Measure inseam, set seat height, drop a plumb line from the knee to pedal spindle, check reach. Or, maybe you did a fit kit or another system where knee angle was measured. This will all work generally fine for a road position, and this is all most bike shops know how to do. If you have not been fit by an aero fit specialist, you are probably set up wrong, maybe grossly so. Also note that just because someone has the latest "Laser-fit-o-rama 2000" fit tool, it doesn't mean they have the slightest clue about bike fit. (see my article here for more on this) All I have to do is look around at a group ride or in the transition area of any tri, and I see alot of awful setups.

The simple fact is this: aero position is a whole different enchilada. There is a lot more to it than slapping a pair of aerobars on your road bike. Ideally you want a fairly horizontal torso which requires a lower front end. Many people equate such a position with PAIN, and for good reason - an aero position will be as uncomforatble as heck unless done properly. It really is possible to be aero, comfortable, and powerful, but you must adjust everything: seat height, seat angle, front end height, reach, etc. We don't believe it is possible to just eyeball your position and achieve fit nirvana. It must be measured accurately, and we don't think that static measures using goniometers and similar devices tell the whole story.

• Aero-specific fit. We know how to fit aero. Many "fit systems" fail to distinguish between road and aero fitting - big mistake!



• We are NOT certified by anybody. Why? Because we developed our OWN system through many years of testing and study that has proven itself among pros and elite amateurs time and time again. Yet it works great for beginners too.



• We use dynamic analysis of you pedaling under load, as opposed to static measurement which may not accurately depict your position.



• We use software to plot your angles while you are working, instead of measuring angles with a device while you are stopped. Angle measuring devices are prone to error, and again they are unable to take measurements while you are moving.



• We can fit you on your own bike - you don't have to translate measurements from a fit bike, a process than can also lead to errors unless done with great care. However, fit bike fittings certainly have some advantages - they are great for finding a "perfect" position without being limited by a particular bike. If you have a bike that is wrong for you, or you are looking to move from an entry level ride to that dream-machine, a fit bike session will take the guesswork out of the process. Our own revolutionary new PATENTED fit bike has been in use in our Lab for almost 3 years now, and we continue to add to its capabilities. Because our fitbike can change all your fit parameters while you are pedaling under load, you can immediately feel the effect of changes, and we can immediately see (and analyze with motion analysis and Spin Scan) what the changes do to your body and pedal stroke. We can repeatedly take all your fit parameters back and forth until we zero in on that perfect fit. Then we use our proprietary calculators to give you a list of frames that will work well for you.



• You don't have to make an appointment and spend 2-3 hrs at a shop. Just video yourself, we do the rest.



• Or, if you prefer a more comprehensive fit session where we take care of all mechanical work, visit us in Rhode Island!



• If you're considering a new bike, talk to us first! We are about fit first and UNBIASED advice - just ask anyone who has used our pre-buy services. We can tell you what specific frames and sizes will work for you, and discuss the pros and cons of just about anything out there. Yes we do now sell bikes - Kestrels - but we will ALWAYS provide you with a list of ALL bikes that could work for you, and we will NEVER recommend a bike that is wrong for you just to make a sale. We have very little floor inventory so we have no incentive to try to squeeze you onto whatever bike we are trying to get rid of!

Let's look at a very simple measurement: seat height.

• If you use a formula, where do you measure to on the saddle? Does your saddle compress or sag when you sit on it? How much? What happens to this formula when you are in an aero position, does it still hold?



• If you use a goniometer, is the measured knee angle really accurate? Are you sure your foot angle is the same as it is when you are pedaling under load? If not, your knee angle could be off.



• If you are measured on a fit bike, are you sure that the height measurement has been transferred accurately to your bike? Is it the same saddle?

All these problems are solved through our method of fitting you on your actual bike while you are pedaling under load.

Now let's get into the nitty-gritty. How low should your aerobars be? Where do you measure from? How far away from your saddle should they be? Do you need a different stem? Saddle? Seatpost? Frame? (Maybe). What is your optimal effective seat angle? Where do you measure this angle? What seat tube angle should your bike have? Can you use a road bike?

The way to answer all these questions is by looking at your body angles. And in our opinion, this doesn't mean looking at them in a "posed", static position on a fit bike. I have seen situations again and again where a person looks fine standing still, but as soon as they have to apply force to the pedals for any amount of time, their position changes radically. Their back arches, they slide forward or back on their saddles, they point their toes, etc. Again, you need to be evaluated under load. Only then do your true biomechanics reveal themselves.

• Sitting too far back relative to bottom bracket (slack seat angle), resulting in an acute hip angle. This typically leads to lower back pain, tired/cramping quads, and lack of power. This in our opinion is one of the biggest error out there. Many frames are simply not built with a steep enough seat angle. Look at many of the top pros in the Hawaii Ironman (See our video and pictures on the home page). They are sitting on the noses of their saddles, and I guarantee it is not because that is the most comfortable way to sit for four and a half hours! They are getting themselves forward enough to open their hip angle for optimal power. Look at TT Champion David Zabriske some time. Sure, he is riding shorter events and doesn't have to run afterwards. But his position is a thing of aero beauty even if it is extreme. He has his saddle set at 78 degrees, but he sits at approximately 85 degrees, almost directly above the bottom bracket. I have measured his angles and they are right in the center of the ranges we look for, even though he has more handlebar drop than just about anybody. The secret is his 85 degree virtual seat angle.



• Aerobars too far away from saddle (reach too long), putting your arms and torso in a weak position, again leading to lack of power and lower back issues. This also causes shoulder/neck pain/tension/fatigue. It can even make you LESS aero due to back-humping (see the sample video). This is very common for women.



• Saddle too low or high, leading to knee issues, lack of power, and comfort (crotch) issues.



• Aerobars too high (not enough drop), typically because the rider is uncomfortable when they are lowered. This is frequently because the bars are lowered without adjusting seating position.

If any of this makes sense, consider getting fit. If it doesn't, let us know why!

copyright 2009 TTBikeFit LLC