Road Cycling - Aero Bars -- Do They Really Increase Speed?

Today, I tried to test the effectiveness of my aero bars (Profile Air Stryke). I stopped at the top of a short 75 yard hill, and let the bike roll down the hill (no power) while I was in the aero position. At the bottom of the hill, I was doing 22 mph. Then I went back up the hill, turned around, and started rolling down the hill (no power) from the same starting point. This time, I was sitting straight up, with my hands on the hoods. At the bottom of the hill, I was doing 22 mph. Why didn't the aero position improve my speed? (Together, the bike and I weigh around 220 pounds).

Hmm...like you said, at the BOTTOM of the hill you were doing 22mph. But you should also take into account acceleration and your average velocity during the trip. For all we know, it could've taken forever for you to reach 22mph w. no aero bars but w. aero bars, you were at 22mph very quickly and stayed there for the whole trip - therefore less time taken w. aero bars

And 75 yards...is (well..I don't really know what that is in SI units) but I'm sure that's a pretty short distance...

edit* not to be a nitpicker :D but there's a difference between velocity and speed :)

75 yards isnt exactly a very long distance to use to test their effectiveness (doesnt seem like it, anyway.).

I think part of it is that they are more effective because of the position created for the rider, and not necessarily the aerodynamics. A rider could get that low without aero-bars but it would require using more energy. (im guessing)

Did you achieve a truely effective aero position? I've given up on aero bars because I can't get down into that aerodynamic position and pedal effectively. One can pedal efficiently, longer, and stronger only when in a comfortable position. To most cyclists, that tucked aero position is very unfomfortable. I fall into that catagory.

The test you did may or may not be very good to make a determination. As far as do they work or not, there is no question about it, it's been tested over and over again. However there's more to being aero than throwing some aerobars on your bike and going for it, in that case you may not be more aero than riding on the regular bars.

Check out;
http://www.bicyclesports.com/tech/display.aspx?view=104511012803.xml
http://www.bicyclesports.com/tech/display.aspx?view=114324010203.xml
http://www.timetrial.org/aerodynamics.htm

i don't even need aerobars to notice the difference of an aero tuck. try this sometime.... on a FLAT section of road, watch the speedo as you pedal at constant effort with your hands on the tops, and your back as upright as possible. now applying the same effort to the pedals, put your hands in the drops, bend you elbows 90 degrees, and get your head down as far as safely possible, and you will watch the speedo automatically start to rise.

tyler stated that the 'experts' claim 45 second time benifit using aeros over not in a 40k tt.

One of the benefits of aero bars is making it easier to close the scoop created by the opening between your arms in the typical down position using drops.

It also forces you to get the ideal flat back position unless your handlebars are too high. This allows air to pass over instead of hitting you in the chest.

The benefits are best measured over a time trial course of at least 10 miles IMO.

Aero bars are obviously intended more for racing, etc than casual riding. The primary benefit for the average joe would be more efficient energy use in the tucked position if, as George suggested, he/she can pedal comfortably. Also, 75 yds would not be enough to see any difference. You still present a pretty large obstacle to the wind and any improvements would be measurable over a longer distance. Find a long, flat stretch and do a test *under pedal power* in the highest gear to see whats going on. Your bike has a limit to non-powered speed downhill because of factors like friction between the tires and the road, bearings in the hubs, etc, etc, etc. The idea to test them on flats is a good one. Ride into the wind and see how much energy (measured as objective time and subjective fatiue) it takes to travel 1/2 mile ~15mph. Try w/o the bars first. If you get the same time the second time w/o much rest, the bars worked.

Post your results. There's always counter-wisdom that revolutionizes the industry (like the now-moot seat height argument). ;)

PS I would think aerobars might be a hindrance with a tailwind... No data to support this other than common ?sense?

Once, riding on my own on a flat road... I began to ride in the aero-bar position. I had no aerobars... I was just trying to balance with my arms off the front of the handlebars. Someone mentioned that its all about comfort... I found it to be a comfortable position, and although I had no speedometer, I could feel that it was slightly easier to ride at the same speed as I was when I wasn't in that position.

They're good for about a 3-4 MPH increase in speed in my case. have Profile Airstrykes on my bike and when I'm cruising along at about 16 - 17 MPH I can tuck down into the aerobars and with no increase in effort be doing 19 - 21 MPH. If I keep pushing I can hit mid-to-upper-20's and hold that speed for miles.I figure part of this is due to the aero position, but some is also due to the fact that the lower tuck stretches the glutes and gets a whole new set of muscles working in the pedal stroke. I can get pretty close to the same results by riding in the drops but not for as long since it isn't as comfortable to me as laying out on the aerobars.

I have been riding with aero bars for 4 years since I do triathlons. All I know is that they do work.

I'm no physicist, but it seems to me (and in my experience) aero bars offer the least benefit on downhills versus flats or even uphill. The effects of gravity would probably equalize any advantages the aero bars offer. The wind isn't going to slow you down very much on a fairly steep downhill.

You really need to ride the flats to see if they give you an advantage. There are also other factors such as your aero position, seat position, etc. that can help you improve your use of the bars.

most triathletes seem to want consistancy in their speed, so getting into a rhythm really helps with a 24 mile TT, which is essentially a biking leg of a tri.

it is possible to get aero without the weenie bars. i just can't seem to get in enough of a tuck to be of benefit. i can, but can't extend my belly to breath well, so it kind of defeats the purpose. i also don't want anything else to effect my bike handling or to add weight.

The aerobars do work. And there is a basic way to think of it to convince yourself they do. Think of a sports car and a UPS truck driving into a stiff head wind. Which one performs better against the wind? If you discount smoothed and curved surfaces and think only of the frontal area projected by each vehicle into the wind, the sports car has a much smaller area, therefore creates much less "form drag" than does the UPS truck, making it easier to maintain speed.

This is the primary reason that the "aerodynamic tuck" works ....it's all about reducing the area that your body places square into the wind.

Then! in addition to reducing the form drag, things like smooth curves on the sportscar (or rider and bike) help by reducing the aerodynamic drag.

Also, the drag does not increase with velocity, it increases with the velocity squared!! ....so small increases in speed make big increases in drag. Your small hill is probably not big enough to make the aerodynamic advantage of the bars obvious. ....try your experiment again on a much bigger hill.

Aerobars help you get into a more aerodynamic position, to reduce aerodynamic drag.
Aerodynamic drag is proportional to velocity squared: If you double your speed, you quadruple your aero drag.
What this means is that at low speed, there is little aero-drag, and at high speed there is lots. Aerobars are most effective at the highest speeds.
The rolling start test is a measure of rolling resistance, rather than aerodynamic drag.
To test an aero-position, find a short flat loop of road and ride as fast as you can sustain, at a constant heartbeat (ie constant power) in the various positions. You should probably repeat the test over several days, to account for variations of power with heart-rate. The best place to test is in a velodrome.

They work great for me as well, but I find an increase of about 2 mph with no increase in effort. Also they seem to work best (and I know this is dangerous) when drafting another rider.

*I will only draft in this way if I am the last rider in a pace line . I'm sure you all know how angery rodies get if you ride your aeros in the middle of a pace line.

Part of the problem is in the acuracy of the speedo to determine the possible increase over such a short distance. Since you say that with aerobars it is 22 mph and without is 22 mph, it leads me to think that such numbers are too "whole." I would have expected something like 21.8 and 22.2. If your speedo registers only whole numbers you may not notice the difference.

My suggestion is get a good speedo that will register a part of a mph. Better yet, change it to kilometers. Then try the same experiment and do it ten times for each condition. Also mark on the road the exact starting point and ending point. Be scientific about it.

This will be good exercise for you too :D

do they work in a cross wind? better in a tailwind?

i can change my position to semi-simulate an aero tuck without the bars.

i am not saying that they don't work....i just think i canm make adjustments on the bike that can simulate the position...

yes but I think effort and comfort may be the key in this; granted weight is the tradeoff.

Thanks for all the good imput on aero bars. Your responses made me aware that I was not, in fact, in a true aero position. I have an adjustable stem (is that the right term?) which is presently at a 45 degree angle. I plan to drop the stem to horizontal and do some experimenting on a five mile flat course. Another problem is, at age 65, I'm down on horsepower. I can't crank hard enough.
But there are benefits to aero bars other than performance. They look cool. Every time I'm out, one of the locals always asks me what the hell these things are. I give them a high tech explanation that makes me seem like I know what I'm talking about. Fooled 'em again! :beer: