So we’ve got plenty of data out now on different frames and wheels, but arguably the aero helmet can make as much difference as those two.
Is there any Data?
I’m looking at buying and there are so many options.
I’ve been looking at the LG Chrono because it looks easy to get on (Only race up to half IM, mostly shorter) and not too bulky - so it doesn’t look like it’d slow me down if I’m moving my head around - but how does it compare.
Also note the Specialized TT2 and Rudy Project have some big ventilation vents, so they could be cool, but are they hard to get on?
What are the important things to look for in an aero helmet - short tail v’s long tail etc…
Most folks can critique a bike now from pictures as to good or poor aero design , how about we start critiquing some helmets - what are the good and poor aspects…
How much time difference between aero helmets or is it just as simple as picking any aero helmet??
**John Cobb once posted a comment that he found aero helmets with the tail pointing up to be a bit faster in some cases than when the helmet is level.
**I suspect that the whole tail pointing up stuff really has to do with the front helmet vents being removed from the wind stream.
Actually…IIRC, John revealed later that smoke trails revealed that for THAT particular case, the tail up condition tended to direct the air up and over some behind-the-seat water bottles that the particular rider used.
So…I wouldn’t make any general conclusions like “tail up is faster” off of that…
Any idea about riders like Millar who we know go to wind tunnels and yet still ride with the tail up?
PS. ta for the e-bay tip; I’ll keep an eye out.
You’ll notice 2 things about that…first, the tail on that helmet isn’t very large…and second, when he (and Zabriskie as well) look down, they also lower their head at the same time. Net gain.
The helmets we de-identified, but it gives you an idea of what is out there.
The appendix also gives an idea of the MIT tunnel balance accuracy/repeatability
One thing that “popped” out at me is how some aero helmets actually reduced the drag as opposed to a bare (bald?) head…while others actually increased the drag…interesting
.
The helmets we de-identified, but it gives you an idea of what is out there.
The appendix also gives an idea of the MIT tunnel balance accuracy/repeatability
One thing that “popped” out at me is how some aero helmets actually reduced the drag as opposed to a bare (bald?) head…while others actually increased the drag…interesting
Tom, I just read that study and a bare head was not included in the testing.
The helmets we de-identified, but it gives you an idea of what is out there.
I did, thank you very much.
What I gathered from that is that
basically all aero helmets offer an advantage over road helmets.
position 3 is not so good, but not much difference between position 1 and 2.
there is 1 helmet in particular that is an “outlier” in terms of having greater drag, and that helmet effects the range.
Most helmets are going to be around the median
The fastest helmet wasn’t significantly faster
I really wish I knew what that really slow helmet was so I could avoid that, as it seems that all the other helmets are going to be ok.
So do we think in conclusion I could possibly just buy any aero helmet that has been designed and released this past year or so as they “probably” have all been tested???
The helmets we de-identified, but it gives you an idea of what is out there.
The appendix also gives an idea of the MIT tunnel balance accuracy/repeatability
One thing that “popped” out at me is how some aero helmets actually reduced the drag as opposed to a bare (bald?) head…while others actually increased the drag…interesting
Tom, I just read that study and a bare head was not included in the testing.
Sure it was (or at least it was “implied”)…all of the results were “normalized” to the mannequin alone. That’s why some of the helmets have “negative drag”. From the thesis:
(Note that this is the drag value of the helmet by itself; drag associated with the mannequin was subtracted out from the final drag value leaving only the value of the helmet.)
I take that to mean that they tested the mannequin without a helmet first as a baseline, and the results shown in the plots are plus or minus from that baseline.
Has anyone seen data or had experience on the Lious Garneu Superleggera dimpled helmet? It seems like no one else is doing the dimpled thing with helmets.
You are correct in your assumption. Also consider that the mannequin’s head is a fair bit more perfect than most people’s heads (and had no hair). So, in short, your previous observation is correct, but if the test was repeated with a more ‘realistic’ human head, I would expect a negative (less drag) shift.
There was one outlier, but there is a caveat to that outlier. For most actual riders that have been through the tunnel with the same helmets, the trends have followed what you see in the paper. There have been a few cases in which the outlying helmet performed better than the others. I have seen it twice, and both with riders who had very rounded backs and necks (and shoulders). My qualitative observations pointed to flow reattachment in these cases, but again, they were rare in the tests that were done, and I don’t often see riders who I think would fall into this category.
I also agree with Gabbiev’s advice. Forward facing vents are not your friend, aerodynamically, but a roll of clear packaging tape will fix that problem for you. An aero helmet is definitely one of the more cost-effective ways of getting your drag down (assuming your position is dialed for the bike you are on).
Mark (MITaerobike) was also there when the testing was being done, and might chime in.
Has anyone seen data or had experience on the Lious Garneu Superleggera dimpled helmet? It seems like no one else is doing the dimpled thing with helmets.
The Lazer Tardiz has dimpled surfaces…but they seem to be in an area that one wouldn’t expect to place a boundary layer trip. So, my suspicion is that they’re mostly about style on that helmet…
You are correct in your assumption. Also consider that the mannequin’s head is a fair bit more perfect than most people’s heads (and had no hair). So, in short, your previous observation is correct, but if the test was repeated with a more ‘realistic’ human head, I would expect a negative (less drag) shift.
There was one outlier, but there is a caveat to that outlier. For most actual riders that have been through the tunnel with the same helmets, the trends have followed what you see in the paper. There have been a few cases in which the outlying helmet performed better than the others. I have seen it twice, and both with riders who had very rounded backs and necks (and shoulders). My qualitative observations pointed to flow reattachment in these cases, but again, they were rare in the tests that were done, and I don’t often see riders who I think would fall into this category.
I also agree with Gabbiev’s advice. Forward facing vents are not your friend, aerodynamically, but a roll of clear packaging tape will fix that problem for you. An aero helmet is definitely one of the more cost-effective ways of getting your drag down (assuming your position is dialed for the bike you are on).
Mark (MITaerobike) was also there when the testing was being done, and might chime in.
Cool…it’s good to know that my reading comprehension is still adequate
So then…how do we pry the decoding key out of you?
