helmet ventilation?

wrote in message
...

Dear Chris,

Actually, the thin metal domes amplify the weak signal
sufficiently to be received by our instruments at a muc
greater distance and allow us in turn to reach and control a
much wider audience.

Kang & Kodos

....and always whirling...WHIRLING!!!! *Bob Dole spinning around furiously in
slightly off-center orbits*

Just zis Guy, you know? wrote:
On Wed, 13 Jul 2005 08:58:53 -0400, "C.J.Patten"
wrote:

When you spend 5 times as much to get something like a Giro Atmos (i
gather they use it on the tour?) is the ventilation that much
better? Would you notice your head staying that much cooler?

I don't think it's anything to do with cost (most properties of
helmets are not, as far as I can tell - some very cheap Chinese
helmets are Snell certified, no Bell helmet is) but there was some
research I heard of recently.

A headform was heated to 42C, and a fan was then blown over it for 4
minutes. Temperature drops were 10.5C for the bare head, 9.1C for the
best helmet, 2.5C for the worst helmet.

So I'm sure there is a big difference in cooling effect, as you
surmise. Finding out where on the scale between, as it were, 13% and
76% reduction in cooling effect any one particular helmet lies, is
likely to be problematic! It is probably a function of the size and
number of vents, but maybe not, and of course these might have a
consequent effect on structural integrity as well.

It's a good question, actually - I don't know to what extent the body
is able to compensate for the reduced cooling. As far as I understand
it the scalp plays the major part in cooling the head, and there is
evidence in respect of cricketers that helmet-induced heating impairs
reactions. I think there are probably as many unknown unknowns as
known unknowns here.

IOW, possibly.

:-D

Just zis Guy, you know? wrote:
A headform was heated to 42C, and a fan was then blown over it for 4
minutes. Temperature drops were 10.5C for the bare head, 9.1C for the
best helmet, 2.5C for the worst helmet.

Of course, there isn't always a fan handy when you are stopped at
traffic lights. Or crawling up a hill.

James

On 13 Jul 2005 23:11:03 -0700, "James Annan"
wrote:



Just zis Guy, you know? wrote:
A headform was heated to 42C, and a fan was then blown over it for 4
minutes. Temperature drops were 10.5C for the bare head, 9.1C for the
best helmet, 2.5C for the worst helmet.

Of course, there isn't always a fan handy when you are stopped at
traffic lights. Or crawling up a hill.

James

Dear Guy and James,

Of course, if our heads actually reached 107.6 degrees
Fahrenheit, it probably wouldn't matter whether we were
stopped, crawling up a hill, or doing 90 mph.

Irrelevantly,

Carl Fogel

wrote:
On 13 Jul 2005 23:11:03 -0700, "James Annan"
wrote:



Just zis Guy, you know? wrote:
A headform was heated to 42C, and a fan was then blown over it for 4
minutes. Temperature drops were 10.5C for the bare head, 9.1C for the
best helmet, 2.5C for the worst helmet.

Of course, there isn't always a fan handy when you are stopped at
traffic lights. Or crawling up a hill.

James

Dear Guy and James,

Of course, if our heads actually reached 107.6 degrees
Fahrenheit, it probably wouldn't matter whether we were
stopped, crawling up a hill, or doing 90 mph.

Cooling to 31.5C doesn't sound like much fun either. Maybe I'll start
to wear a woolly hat.

James

On 13 Jul 2005 23:11:03 -0700, "James Annan"
wrote:


A headform was heated to 42C, and a fan was then blown over it for 4
minutes. Temperature drops were 10.5C for the bare head, 9.1C for the
best helmet, 2.5C for the worst helmet.

Of course, there isn't always a fan handy when you are stopped at
traffic lights. Or crawling up a hill.

Unless you are Ivan Basso, in which case you have no shortage of fans,
mostly female (but they are not looking at your head).

Oh, /that/ sort of fan. As you were, then...


Guy
--
http://www.chapmancentral.co.uk

"Let’s have a moment of silence for all those Americans who are stuck
in traffic on their way to the gym to ride the stationary bicycle."
- Earl Blumenauer

On Thu, 14 Jul 2005 05:12:06 GMT, "Bill Sornson"
wrote:


IOW, possibly.

Yep, or possibly not. But I don't think cost is going to be a
particularly reliable indicator.


Guy
--
http://www.chapmancentral.co.uk

"Let’s have a moment of silence for all those Americans who are stuck
in traffic on their way to the gym to ride the stationary bicycle."
- Earl Blumenauer

I had a solid helmet I broke in a fall last year. The replacement is a Bell
with vents. I don't notice it's any cooler.

--
Bob Burns
Mill Hall PA
(email is spamtrap)


"C.J.Patten" wrote in message
...
I won't get in to a helmet debate. I wear one, reasons irrelevant for this
thread.

My question has to do with vents.

My current helmet is a Giro Indicator. This wasn't an expensive helmet but
it fits well.

When you spend 5 times as much to get something like a Giro Atmos (i
gather they use it on the tour?) is the ventilation that much better?
Would you notice your head staying that much cooler?

Any other extremely vented helmets? (don't say "bare head" smart-asses)

Thanks,
Chris

Bob Burns wrote:
I had a solid helmet I broke in a fall last year.

That's what you get for wearing a helmet.

snipped
Oh, /that/ sort of fan. As you were, then...


Guy
--
Wow...."As you were" ...I haven't heard that expression since Camp
Pendleton!

Semper Fi!

John



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