Sunday, April 27, 2008

Aero Bars

I have wondered what the deal with aero bars is for some time. All serious triathletes use them. But why?

Aerodynamics, I've been told. Well, ok. So why don't the guys who do Tour de France use them? You know, the pro cyclists? Surely if being aerodynamic made that much of a difference in speed then everyone would be using them. Surely.

So why do triathletes use them? And why do tri bikes have flat tubes and road bikes round ones? The standard answer is always 'aerodynamics.' They are called 'aero' bars, after all. But that can't be all there is to it. Again, if it were that great, the pro cyclists would be using it, too.

Also, I know pro cyclists spend a lot of time and money making sure their aerodynamic position is perfect. Remember that "Chasing Lance" series on the Discovery Channel? They showed him in a wind tunnel with an aero helmet changing his body position ever so slightly, making sure he was as aerodynamic as he could possibly be. He wasn't using aero bars.

And why does our local cycle club discourage the use of tri bikes in their group rides? That I found truly baffling. Was it just road bike purist snobbery? What could the big deal about dropping down into aero position possibly be?

There was something there. Something I was missing. Some reason why triathletes use tri bikes, and very expensive ones at that, and cyclists ride (also very expensive) road bikes. But what?

The answers to these questions has taken me a surprisingly long time to find. Months of googling, talking to cyclists and triathletes, reading articles, and bike shopping. Just in case you've pondered the same questions yourself, I bring you the answers that I've found at last.

And let me point out that a whole lot of triathletes don't know what I'm about to expound upon here. "Aerodynamics" is the extent of the reasoning behind why they ride a tri bike. That and because everyone else does. So let me 'splain, to those of you who care and don't already know this:

First of all, it's not just that a tri-bike has aero bars. The entire geometry of the bike is different. On a road bike your position is flat. On a tri-bike, the frame is shaped such that you ride with your butt up and your shoulders low. You rest your forearms on those aero bars and really get low. The reason for this is not aerodynamics. It is so that you use different muscles in your legs. Instead of pushing down on your pedals, you are actually pushing back somewhat. You're using more butt muscle and different parts of your quads and hamstrings. Those are now different than the parts of the muscles used in running.

It is also an aerodynamic position. This makes you somewhat faster. So why don't pro cyclists ride this type of bike? Turns out they do. For time trials. In situations where they are riding alone and nothing but speed matters, they ride an aero bike.

Why don't they ride them in a peloton? Because a tri bike is not as maneuverable as a road bike. A tri-bike is super-stiff and does not respond as quickly as a road bike. In the tight quarters of a peloton, you need to be able to react to the guys around you instantly. Riding a tri-bike in a situation like that means you are likely to cause a wreck. No wonder cyclists don't want to ride with a guy who is on one.

But in a triathlon, where drafting is not legal, quick responsiveness is not as important as speed.

A tri-bike is also more uncomfortable than a road bike. It's not a bike that you're going to ride for over a hundred miles, day after day. It's hard on the neck and shoulders especially. If you're not going to jump off of it and run afterwards, you don't want or need to put yourself through that kind of suffering.

You'd think that clipping an aero bar onto a road bike would be the best of both worlds, but it's not. Clips-on allow you to get a more aerodynamic position, yes, which is nice for downhill and windy situations. They allow you to rest your arms and upper body a bit, too. If you buy the right clip-ons you can get adjustable pads that you can move to be right under your shoulders, so that's a good thing. But clip-ons don't change your bike's geometry and thus don't do anything to benefit your run. Clip-ons could make you a little more comfortable on portions of the bike ride, but they won't make you a faster runner.

I read an article somewhere (sorry, no link. Forgot where) that said the aero-bike geometry with aerobars is an invention that changed the sport of triathlon on par with sports discoveries like the Fosbury Flop changed high-jumping and putting the skis into a V-shape changed ski jumping. That's huge. Huge.

But it's not that a tri-bike with aero bars makes your bike time that much faster. It'll be a bit faster. Maybe a mph or two. The real time saving will be gained on the run. You use different parts of the leg muscles in biking and running now, so your running muscles are fresher. You won't have to spend the first two miles or so working through aches and cramps as your legs adjust from biking to running. Instead, you'll run right off the bike. You will run closer to your fresh running pace throughout, not your 'OMG I just rode for hours and my legs are tired' pace. So your overall finish time will be faster when you use an aero-bike, mainly thanks to a faster run time.

Basta rides a road bike. He bought it about a year and a half ago, when we first got the idea that we wanted to become cyclists. It's a Specialized Roubaix. A good, entry-level bike. It retails for around $1300. He's ridden a lot of miles on it, he's very fond of that bike, and he's made good gains in his biking skills with it. He did Oceanside on it.

But now that he's a triathlete, he's completed a Half Ironman, and he has his sights set on a Full, he needs a proper triathlon bike. Now that I understand the benefits, I know he absolutely needs one. He wanted to hold off until his Full, but I want him to get one for his upcoming Vineman Half.

Let the shopping begin.

14 comments:

High Altitude Triathlon Club said...

Thank you. Thank you, thank you thank you!!!


I have just started doing triathlon and I like my road bike, but I have bike envy! My friends $$$ tri bikes look so cool and now I finally know why road bikers don't use them.


So again I say thank you for your post and extensive research - now I don't have to do it!



The only thing I will say is that my road bike and clip on aero bars combo do make a heck of a difference for me - especially in a head wind. I love them.

Anapico said...

I'm happy you found this useful. A few other people have also told me that their clip-on aerobars are useful on the bike in certain situations, especially in the wind. That's good to know, and I imagine it's because of the aerodynamic position. Slicing into the wind with the aerobars and hands is more efficient than just dropping down to the lower handles and meeting the wind with the helmet first.

But clip-ons aren't going to help your run time at all. You need the tri-bike for that.

Anonymous said...

I thought I'd heard that moving the seat, etc, on a road bike + aerobars could put you in a tri bike position. Did you find any info on that in your research?

Anapico said...

Yes, I did. The answer is no, trying to turn a road bike into a tri bike doesn't accomplish any of the goals of having a tri bike (saves the legs & faster) but it does make a perfectly good road bike slower. I'll leave it to the experts to explain why, along with some other really good info on road vs tri bikes. Read this:
http://www.slowtwitch.com/Bike_Fit/General_Fit_Articles/Tri_road_or_tweener__647.html

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jared said...

Thanks for taking the time and writing up this article. I too have a Specialized Roubaix sl2 Elite and am doing my first short course tri next month. Was wondering about the tri bike and putting on aero bars. I never thought I'd use them as I ride in the down position a lot more now while training and after reading this I know I really don't need them to compete better in the tri; but rather as a comfort in wind or other times when a different down position might be a nice change.

Giles said...

Another thing missed from the reasons why road races don't use aerobars is that of safety. In the aero position the hands are further from the brakes, and in an emergency an extra second or maybe more of reaction speed is required. This means in road races where drafting is allowed, the increased reaction time in close riding for aero drafting could easily result in huge pile ups. In triathlon events where drafting is forbidden, aerobars are allowed because the riders are well separated, however in draft legal events, tribars are restricted just like road races for safety reasons.