Tuesday, 4 March 2014

Aero Road Helmet Testing - Round 1 (Prevail, Evade, Melb Bike Share)

Aero road helmets have been WorldTour trendy for a while, with most teams sporting an aero version of their standard road helmet. Aero road helmets from Giro, Kask, Specialized, Bell, POC, even Lazer with their GladWrap covers are all seen in the peloton.

Googlering away for aero road helmet reviews, I found a lot of reviews based on looks, weight, price, yet not a lot of data. Some manufacturers published their own data to make the sell. I don't trust any "data" published by the same company trying to sell me something. I'm interested in the proof. Independent tests. The actual benefit of something being sold as a performance enhancer, or to use a term to better increase the SEO of this post, a marginal gain.
The only true test would be a wind tunnel, an indoor velodrome, or some funky iBike paired with a power meter. Without any of these, I waited for a very calm day and ran a number of five minute power tests at different speeds on an outdoor velodrome (Packer Park) and flat section of road (Richmond Boulevard).
Yes I wrote the results down! Never trust technology, much. :)
Equipment: Road bike (as pictured). Standard road wheels. Short sleeve onesie 'crit suit'. Quarq power meter (zeroed before each test). Garmin 800 head unit.  No gloves. No shoe covers. Water bottle on the down tube.

Helmets: Specialized Prevail (M), Specialized Evade (M), Melbourne Bike Share (M), and Limar Crono (L). The Crono TT helmet was added to the mix to make sure my testing was working, it should score lowest on each test.  

Method: 5 minute intervals maintaining a set speed. Static position on the bike (hands on hoods, slight bend in elbows, standard road position). 

Tests 1&2: Velodrome. 38km/h and 43km/h.

Test 3: Road. 41km/h out and back. Pausing the data recording for the u-turn.

Click the image to load full size.

Conclusions: For me, I'll keep wearing my Prevail for training, it'll be a harder workout. Is an Evade worth it? Yes compared to a Prevail. Absolutely not compared to a $5 Melbourne Bike Share helmet.

I really wasn't happy with the two velodrome tests. Even with next to no wind, my speed/cadence/power was oscillating every 10-15 seconds from the bends to the straights. The averaging takes care of this, however I don't think it was truly representative of real-world conditions.

Test 3 on the Richmond Boulevard produced some very interesting data, a massive 16W difference between the Evade and the $5 Melb Bike Share helmet at ~41km/h. This needs to be investigated more.

Further Testing: More road testing. More helmets. I definitely need more data on the Evade vs MBS battle. I'll use the Prevail as the control and not bother with the Crono. Round 2 will be very interesting.

Steele von Hoff - Winning national championships and hearts.... in his aero road helmet


Jose Areta said...

Good stuff Shane. Have you thought of doing this at DISC? There is the possibility of calculating drag coefficient from speed/power in an indoor velodrome. I'm happy to collaborate on doing more testing in an indoor velodrome and workig out the numbers if you are interested :)

Stephen Lane said...

Time to get the iBike out I think!! at least it is one more number to play with! it actually gives a Cda value..

Shane Miller - GPLama said...

Initially I'll keep it as real-world as possible. Using just a power meter, open roads, and using a method that anyone with the same tools can do themselves. Tunnel time, CdA, etc is the true science.. but complicates the answer to the question - "What helmet is better?"

Banked velodromes take a lot of skill to ride the banks/straights at a steady speed/power. I think the iBike option will be the next addition. Then if things progress I'll look into a DISC test.

Jose Areta said...

True, still doing a test in an indoor velodrome is more real-world than wind tunnel testing and certainly very applied. The advantage of a controlled environment is precisely that it allows to detect if the differences are due to the helmet or other confounding factors (mainly wind). As Stevo staid, adding the iBike measurements would be interesting but I still wouldn't trust it as much as testing in an indoor velodrome with known temperature, barometric pressure and relative humidity. I don't have a weather station, but would certainly get one for the sake of running these experiments.