helmet ventilation?

Per C.J.Patten:

Quoted message said:

that's a tease!

Amen.
--
PeteCresswell

Booker C. Bense said:

IMHO, the big difference between cheap and $$$ is ventilation
and weight.

Don't forget protection.

If you pay $130 for a helmet, it's guaranteed to keep a decapitated
head under 300 gees in a 14.01 mph impact.

Whereas if you pay $15 for a helmet, that decapitated head may not hit
300 gees until, oh, 15 or 16 mph.

OK, it's not a big difference. And nobody will ever tell you the exact
numbers. But the difference is there. The more you pay, the less
protection you get.

- Frank Krygowski

Just zis Guy said:

C.J.Patten said:

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 said:

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

James Annan said:

Quoted message said:

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.

Quoted message said:

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

Bill Sornson said:

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" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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 said:

I had a solid helmet I broke in a fall last year.

That's what you get for wearing a helmet.

<snipped>>

Quoted message said:

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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In article <[email hidden]>,

C.J.Patten said:

"(PeteCresswell)" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Per Ron Hardin:

Quoted message said:

t's a 1975 Bell mushroom helmet, a pleasant sun-reflecting white with
rigid
white styrofoam insulation, so it takes off all the radiative solar heat.
That's
a huge benefit. Riding without it is much hotter, very noticeable.

Now you've got me thinking it's the color. Mine's a dark-ish grey.
Maybe a little strategically-applied spray paint...

Better yet, get some aluminum foil. It's easy to mold and with a bit of 3M
spray tack, you can stick it to the helmet.

An added plus: aliens won't be able to read your thoughts anymore.

A fine attempt at misinformation. The aluminum foil is to block
the secret government mind control signals.

--
Michael Press

John said:

Quoted message said:

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

Quoted message said:

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

As Guy is too young for National Service (aka compulsory call-up) it
probably means that he, like me, went to a grammar (high) school with a
compulsory army cadet force (CCF).

Mike

I googled around and found that you can get the article from
http://dx.doi.org/10.1046/j.1460-2687.2000.00053.x. Unfortunately you have
to pay for it...

It was also published in the Jan/Feb 2001 Bicycling Australia if you can
find a copy of that.

Nick

"C.J.Patten" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Well heck, that's a tease! I gotta find that study!
Thanks for that though... good to know.

"Nick Payne" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Someone at RMIT published research on this in Bicycling Australia a
couple of years back. Can't remember the exact details, but I think they
stuck temperature sensors in/on a headform, heated it, then blew air
across and measured the rate of cooling with various helmets (and also
with no helmet as a comparison). There was no correlation between price
and and how well the helmet allowed cooling to take place. Some of the
cheap helmets with what appeared to be poor ventilation were near the top
of the list and some of the expensive ones which were mostly slots were
near the bottom. And the best of the helmets allowed cooling as rapidly
as a bare head.

Nick

"C.J.Patten" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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?

Mike Causer said:

Quoted message said:

Quoted message said:

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

Quoted message said:

Quoted message said:

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

Quoted message said:

As Guy is too young for National Service (aka compulsory call-up) it
probably means that he, like me, went to a grammar (high) school with a
compulsory army cadet force (CCF).

Actually I went to a 1,000+ year old public school (that's Brit-speak
for a private school) which had an /optional/ combined cadet force
(CCF) which I did not join. I was an officer cadet for a short while
at University but failed medical due to asthma. This disability means
I find it hard to maintain an average speed of over 20mph for more
than a couple of hours when riding solo on open roads.

I have no idea where I got the phrase from, possibly my father (who
was in the RAF) or maybe it's just one of those British phrases you
pick up in books.

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

J

Quoted message said:

Actually I went to a 1,000+ year old public school (that's Brit-speak
for a private school) which had an /optional/ combined cadet force
(CCF) which I did not join. I was an officer cadet for a short while
at University but failed medical due to asthma. This disability means
I find it hard to maintain an average speed of over 20mph for more
than a couple of hours when riding solo on open roads.

I have no idea where I got the phrase from, possibly my father (who
was in the RAF) or maybe it's just one of those British phrases you
pick up in books.

Guy
--

It's a standard military phase meaning "disregard my last command" or
something similar. I heard it used many times in the USMC, but that was
40 years ago. Don't hear it much in the civilian world.

Sorry about the asthma holding you back on your faster rides. My lungs
are fine, it's the years that have taken their toll. Can't do much
about that, except train harder.

John

you know? said:

Actually I went to a 1,000+ year old public school (that's Brit-speak
for a private school)

Which school managed that feat? I don't even know of any universities
anywhere that are more than a millennium old (Googling, though, there is
one that just barely qualifies: Al-Azhar in Cairo, Egypt, has been
operating since 969 AD, and 2 of them in India that predate that one by
some bit). Hmmm..

The only pre-1000 AD schools I can find in Britain are:
The King's School, Canterbury (597)
King's School, Rochester (604)
St Peter's, York (627)
Warwick School (914?)
St Albans School (948)
King's School, Ely (970)
[the next one is listed as 1096, do not even close to 1000 years old]

I would guess you attended one of the latter two, unless it was one not on
the list for some reason?

Jasper

Quoted message said:

If you pay $130 for a helmet, it's guaranteed to keep a decapitated
head under 300 gees in a 14.01 mph impact.

Whereas if you pay $15 for a helmet, that decapitated head may not hit
300 gees until, oh, 15 or 16 mph.

OK, it's not a big difference. And nobody will ever tell you the exact
numbers. But the difference is there. The more you pay, the less
protection you get.

So if I pay $1000 I get to ride helmetless but it actually looks like I
have one?

Jasper