I don’t know if anyone can validly answer this, but what is the breakdown, in % of total benefit, of each component of an aero helmet’s superiority:
Solid surface (for air to travel over and theoretically stay laminar; this effect in isolation can be replicated by taping vents shut on regular helmets)
Extended tail surface and other aero benefits of shape (to push turbulent air back further and create more pleasant streamlining around the back; this effect can be replicated, likely not very well, by attaching a triangular wedge shape to the back of a regular helmet)
Again, values should add to 100%… what do people think?
as has been discussed here often, you are missing the 3rd key element…
the way the helmet interacts with the back profile of the rider.
making helmet selection a (if you are worried about the “BEST”) wind tunnel/field testing process.
althought I suspect that field testing part may not offer the fidelity to resolve that. TnA? do you think one could “chung” the helmet differences?
actually, funny you should ask, but here at my “lab” I have a bell vortex, spuik, rocket (m) and rocket (l) waiting for just such a little project. too bad tomorrow I will be flying to WI for 8 days.
I don’t know if anyone can validly answer this, but what is the breakdown, in % of total benefit, of each component of an aero helmet’s superiority:
Solid surface (for air to travel over and theoretically stay laminar; this effect in isolation can be replicated by taping vents shut on regular helmets)
Extended tail surface and other aero benefits of shape (to push turbulent air back further and create more pleasant streamlining around the back; this effect can be replicated, likely not very well, by attaching a triangular wedge shape to the back of a regular helmet)
Again, values should add to 100%… what do people think?
My guess is about 50/50
Seriously, I’ve measured a difference between an LG Rocket and an LG Chrono of ~.005 m^2 of CdA. I’ve never tested either against a “standard” road helmet, but IIRC the difference between a road helmet and a “full aero” helmet is around .010 m^2 total. Since the difference between the Chrono and the Rocket is mostly the addition of the tail (ear flaps too), that’s where my 50/50 guess came from.
That said, that’s a total guess and it’s based partly on my personal head position. I’ve seen results that suggest that the effect of the tail can be greatly influenced by the rider’s head position. YMMV, etc.
My guess based on testing the LG Rocket and Chrono is that 2) accounts for most of the difference. These helmets are pretty much identical, except for the tail and the shell coming down over the ears on the Rocket. The difference between the two was huge – something like 90 secs over 40K. I don’t know how either compared to a standard road helmet though.
Part of the joy of new product development is spending, quite often, large bundles of cash to get your own unbiased answers. You have to go and do research on helmet/rider interactions and come up with a plan that you believe in. In cycling, going off of some published data to develope something new and revolutionary will usually lead to sadness. Then you have to be willing to venture down a road full of hidden land mines, learn what it takes to get new products to pass safety test, learn how to work with manufacturers with a different agenda and then discover about basic marketing. Helmets will be easy, bikes are harder.
making helmet selection a (if you are worried about the “BEST”) wind tunnel/field testing process.
althought I suspect that field testing part may not offer the fidelity to resolve that.
I would have thought so as well, but the testing we did on ADT back in June revealed a clear difference between two of the currently-popular aero helmets.
here at my “lab” I have a bell vortex, spuik, rocket (m) and rocket (l) waiting for just such a little project.
What size is the Spiuk? That was one of the helmets that we wanted to test, but we couldn’t get one in time.
