IIRC, spheres are not very aerodynamic. I'd go with none of the above, and I'm not sure shrink-wrapping it helps, since a lot of helmets are reliant on the airflow to optimize aerodynamics. There's more information in a recent thread about helmet visors.

I appreciate you chiming in, but that really did not answer my question. Would you recommend that I replace my head with something that is not a sphere?

Are you aware of a helmet that has a tail that points more downwards than others, so that when one is in a head down position, the tail is not sticking up? Thanks.

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Two wheels good. Four wheels bad.

This is was the post I was thinking of: http://forum.slowtwitch.com/...o=ASC;mh=25;#4942387

Some helmets make your head shape more like an ellipsoid.

Not aware of a helmet that meets your spec; is there a reason you prefer the head down position?

I prefer head down because I need to get another 40 - 50 years out of this neck and it's not holding up too well as it is. Why not be comfortable? It's a hobby afterall, so I'd like to enjoy it.
I was also under the impression that the reduction in one's frontal surface area by not having one's head sticking up in the wind would be significantly more aero.

I think the problem with helmets (when looking for one specifically to enhance head down riding) is that they are designed to be more "ellpitoid" front to back (forehead to occiput) and not so much from top to bottom (crown to shoulder).

So if anyone has a helmet that is more elliptoid top to bottom, I'd love to hear from them.

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Two wheels good. Four wheels bad.

Honestly, hard to tell.

The WalMart helmet has better shaping (the LG's vents are optimized for a specific head angle), but it has a larger profile.

Maybe Jim from ERO can comment on testing with the LG in head down positions.

You are probably better off with the tailed aero LG in your profile pic. In head down; the tapering along the ear flaps and base of the head helps reduce pressure drag, even though the tail is sticking up.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

I think you're going to have much better luck with the position in the pics on the right, where most aero helmets will allow you to maintain an aero profile. For a helmet to be the right shape top to bottom, it'd effectively look like an aerofoil conehead, and I haven't seen anything remotely close.

I'd definitely avoid anything with air vents if you need the position in the left pics though. May be a scenario where the Giro Air Attack works well.

Bell Javelin might be a pretty good candidate. My head position looks pretty similar to yours in the right photo and the Bell sits perfectly flush with my neck:

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ZONE3 - We Last Longer

you may be correct, though it seems you are looking up a bit. Very nice pic.

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Two wheels good. Four wheels bad.

Thanks. I'm looking just up enough to see the road ahead at the top of my brows. Usually my eyes are fixed through the bars, about a metre up the road from the front wheel. There's leeway with the helmet to roll it a bit further back on the head, and the tail is relatively short so I don't think it makes a huge difference if it's slightly less flush - you can definitely look a bit more down with it.

That being said, the Selector might be worth checking out - comes with two different-depth "tails" that would fit between the Javelin's bottom and my back, filling any gaps that might come from holding your head down.

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ZONE3 - We Last Longer

I was looking at pics of the Rudy Project Wing 57 - it seems to have a crest so that it is not so round both around the front, and top to bottom, which may help a bit while looking down. I don't know how its little stubby tail would line up, but I may give it a try.

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Two wheels good. Four wheels bad.

Please see update pic above. What do you think about the Rudy? It looks better to me than the other two, and it has a bit of a crested contour unlike the other two, so not a flat sphere will be hitting the wind.

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Two wheels good. Four wheels bad.

It looks better from the front but I'm not sure what effect the tail of the helmet not being flush with your back will be. Can you borrow a power meter to field test the helmets? Only way to definitively tell.

I'd push the Rudy TT helmet back on your head (more of your forehead exposed).

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Mat Steinmetz

51-SPEEDSHOP.com - instagram - @matsteinmetz - facebook

I am in the same boat.

Here is MY plan...

I am trying 3 very different helmets out to see how they do.

I plan on going outside and riding a stretch of good road on a day with either little to no wind OR a light wind that is constant.

I am going to try and hold a consistent power level for the whole way out, stop, turn around and back. Maybe something on the low side that I can keep real steady like 160 watts.

I am then going see how much difference in time I had with the three helmets.

I am just wondering how much road I need for a valid test?? 1 mile out and back?? 3 miles??

I would think there would be a lot of variables on a road test like that that would make the relatively small contribution of the helmet hard to detect (especially over a relatively short distance). How do you control for: exact wind conditions both trials, exact same track your bike must take, your physiology (even on a short trial, your body will NOT be exactly the same both times), your exact body position.

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Two wheels good. Four wheels bad.

Yes, so short of having a wind tunnel or indoor track what do you think would be the best way to test for how well a helmet either works or dissent work??

I think if you hold the same watts, ride the same track and the wind is not variable the test is at least somewhat valid.

Can think of anything else?? I am fresh out of ideas.

I suggest you read the platypus thread for how to do field tests:

http://forum.slowtwitch.com/..._reply;so=ASC;mh=25;

This will tell you to accurately test this sort of thing. If you do it well it will be able to determine very tiny changes in drag. One of the keys is to do very short loops, but lots of the them and varying your power.

Evade.....

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"I would definitely smell her seat after a century ride"

Helmet contribution to aerodynamics is not small (on of the larger aspects) and field testing with a good power meter can definitely pick this up using AeroLab. My testing results with GC very closely mirrored by a session with AlphaMantis, which is pretty damn good.

Top

I did that with my RP Wingspan (worked well to get the tail down). Had to remove the dial fit adjuster (it's velcroed on, so easy to remove).

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

yeah, i think tipping it back will work. The Wing 57 has an adjustable dial strap, so in its most shallow configuration one seems to be able to tighten the wheel under the back of the head which hopefully would prevent it slipping down in the front. I will try that.

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Two wheels good. Four wheels bad.

I found that even in the shallowest position the dial pressed against the back of my neck and prevented it from rotating as far back as I liked. As mentioned, it's attached to the straps with velcro and easily uninstalled (and reinstalled if you want to put it back).

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

tesser...you are one skinny little puppy!