Do You Really Need a Time Trial Helmet

louis garneau course skinsuit

Do You Really Need a Time Trial Helmet: Putting it to the Test

When Giro released their latest and greatest time trial helmet the Aerohead last summer, they also released aerodynamics data on their helmets that really struck me.  You can see the data for yourself in the chart below.  At the time, I was considering buying a Giro Selector time trial helmet but the numbers Giro released changed my mind.  According to their testing, their Air Attack road helmet was only 2.1 seconds slower than the Selector over 40kms at 400 watts.  Since I already had an Air Attack, I figured I could save my money and just use that for time trials.

Giro’s numbers got me thinking: do you really need a time trial helmet or are the savings negligible enough that you could use an aero road helmet without losing too much?  In order to satiate my curiosity, I decided to put it to the test myself.

The Test

Without a wind tunnel or fancy computer programs, the test would be simple.  I would do two runs over the same time trial course riding at the same target pace each time.  I would switch helmets between the two runs while keeping everything else consistent in order to control as many variables as possible.  Whichever helmet produced the quickest time would be considered the fastest.

The course I used was the local club 15km time trial course.  Its your basic out and back course, pretty much pancake flat, relatively straight and non-technical.  I’m sure your local club has a similar course that they use for weekly time trials that you could use for testing of your own.

The bike I would be using is my ghetto TT bike, which was cobbled together out of parts from my parts bin, and I was wearing the Louis Garneau Course Skinsuit.  My trusty Stages power meter would be used to consistently pace my efforts at the target 250 watts with the Wahoo Element collecting the data.

The two helmets I would be testing are the Giro Air Attack for the aero road helmet, as used in the initial testing, and the Louis Garneau P-09 for the time trial helmet.

time trial helmet

Now remember, this test is far from scientific.  Two runs with two helmets is too small of a sample to draw any real conclusions and there are too many other variables out of my control, most notably changing weather conditions.  All the companies that have published numbers used expensive wind tunnels and fancy software, but this test will still give you an idea.

The Results

Helmet Time Average Speed Average Power
Giro Air Attack 25:23 35 km/h 247 w
Louis Garneau P-09 24:59 35.6 km/h 251 w

As you can see, the Louis Garneau P-09 came out as the winner by 24 seconds over the Giro Air Attack.  The average power for the second run was 4 watts higher but the wind had picked up on the second run, resulting in a headwind on the return leg.  So even though the average power was higher, most of the extra watts were used fighting stronger winds which still makes the results valid in my opinion.

time trial helmet

My results line up with testing done by other companies.  In their “Win Tunnel,” Specialized showed that their S-Works Time Trial helmet was 20 seconds faster than their Evade aero road helmet over 40km (which was 40 seconds faster than the Prevail).  So clearly there are some gains to be made by switching from an aero road helmet to a time trial helmet.


In conclusion, a time trial helmet is a worthwhile purchase.  For what is a relatively inexpensive purchase, you can save significant amounts of time.  So if you are looking to maximize your aero gains or reduce your drag without breaking the bank, a time trial helmet is a good place to start.

If you are looking for more advice on how to cheat the wind without spending the GDP of a small country, check out Aero on a Budget Part 1 and Part 2 or Budget Time Trial Shoot Out for more aero testing fun.