Proper Aerobar Fit

Proper Aerobar Fit
Coach Steve
Written by Coach Steve

I can remember racing with regular drop style handlebars in USCF time trials for years; my back would be screaming by the end of most TTs over 30-minutes. Then came aerobars. It was a whole new deal, not only for comfort, but for speed as well. Optimizing your position on aerobars is important; just putting them on your bike and hoping for new comfort and “free” speed is not enough. I see too many riders struggle with aerobar positions that aren’t even close. For the record, most ineffective aerobar positions I see at the races are set too long (over-extended), and too high.

Speed gains with a properly set-up aerobar position are significant, well worth the additional weight of your complete bike. Faster riders will gain proportionally more speed than slower riders, especially on the flats and downhills. For most riders at climbing speeds there’s little or no advantage to maintaining an aerobar position.

First I’ll assume that your seat position is completely dialed-in. Keep in mind that to slide your seat forward (or back) to change the distance to your aerobars is not an acceptable way to set your reach. You need to choose the right length or adjustable aerobars from the outset.

In choosing the type of aerobars, the kind of handlebar they’ll mount on makes a difference; you’ll need to choose the correct type of aerobar to clamp on to either your drop bars, bullhorn bars, or complete bullhorn bar/aerobar unit. With drop bars you’ll need an aerobar that mounts as low as possible so that your forearms rest right at the level of the tops of the bars. With bullhorn style TT bars, the aerobars you choose should have some extra height above the point where they clamp on, as a properly fitted bullhorn bar and stem combination will be significantly lower than drop style bars.

Some models of aerobars have an adjustment for length, some don’t. For clip-ons on drop bars you should choose an aerobar length where your hand position does not go more than a couple inches beyond the brake levers. ITU pros who race Olympic distance (and draft legal junior racers) are limited to drop style bars with an aerobar that doesn’t go beyond the furthest forward point of their brake levers. This is for safety reasons, but in fact gives a good position when the drop bar’s position is optimal. It’s not usually as comfortable as a dedicated tri/TT bike with bullhorn/aerobar though.

There are many one-piece combination bullhorn/aerobar units available. Do your research carefully before buying to make sure they will work with your current frame’s top tube length. Also make sure the front end of your bike is low enough, as bullhorn bars are positioned lower than road style drop bars. In a few cases for small riders a 650c front wheel is needed. I favor a unit with separate stem so you can change length and adjust angle.

Aerobars that don’t have a length adjustment typically come in three lengths (S/M/L). There’s usually a guide on the box where you measure your forearm length for proper fit. Keep in mind that if your handlebar position is correct most of your forearm length is already figured-in, so I find few if any riders need the longest length, with the small and medium sizes working for the majority.

You’ve chosen the aerobars and are mounting them on your bike. Here is how they should fit:

  1. From a side view, your forearms should be level. Some wind tunnel tests found forearms tilted up also gave a low drag coefficient, but level forearms give a better balance and feel on the bike with excellent low drag numbers.
  2. Again looking from the side, the inner angle between your forearm and upper arm should be 90 to 110 degrees. If this angle is greater than 110 degrees (common), the reach to your aerobar is too long; it may cause lower back problems and leave you with less leverage/power. If this angle is less than 90 degrees, you’re too close (rare). Usually this means your bike’s top tube, or stem length is too short. In rare cases your aerobar may be too short.
  3. Set your elbow width with comfort as first priority. Narrow elbows are not always faster; hands together out front with elbows apart in a “V” shape will direct airflow around body and can be just as fast as elbows close/forearms parallel.

The closer to horizontal your back is, the lower your aerodynamic drag coefficient will be – a very good thing. But for many athletes their lower back/hamstring flexibility limits how low they can go so setting an aerobar position one can comfortably maintain for the race’s duration is key. I’m typically on my aerobars for 95% of the race. I only come off the aerobars for quick accelerations, braking, very sharp corners, and steep (small chainring), or stand-up type climbs. An Ironman distance athlete holding the position for hours may need a higher position then sprint distance specialist.

Finally, use the aerobars every chance you get in training; the more you use them the more comfortable it is to maintain the position on race day!