J
Just zis Guy, you know?
Guest
In reply to Bill "Laa Laa I'm Not Listening" Zaumen:
Every one of the links you posted referes solely to aero helmets. Those
which quote actual figures, the first one excepted, are all based on the
same study - and it's the same figure as in Rinard's piece
(http://damonrinard.com/aero/aerodynamics.htm), so comes from
the original Kyle paper as already discussed ad nauseam. Maybe it's time to
resurrect the old nickname "Bill *only-one-study-in-only-one- country*
Zaumen"! Just to remind you
of the context of the 2% figure which is the only number quoted in all but
one of the studies you link:
"Aero helmets, as they are used for racing, which do not
however meet the ANSI safety requirements, reduce the
aero drag by approximately 2% compared to a bald head or
a rubber cap over the hair. "
All of this is obvious to the casual reader, indicating that you probably
did not go further than the Google summaries.
So now to the links:
<http://www.mecheng.adelaide.edu.au/courses/undergrad/projects/level4papers2
001/chin_lim.pdf>
"Design of an aerodynamically sound bike helmet" - i.e. a theoretical paper
on how to remedy the fact that bike hlemets are /not/ aerodynamically sound.
Quote from abstract: "helmet will increase the frontal area of the rider's
head and this will affect the aerodynamics of the rider, thus, the rising of
drag. Therefore, helmet must have a good aerodynamics shape to minimise the
effect of the frontal area. Two track cycling helmets are used to
investigate the performances of drag in different position."
So Frank's comment re greater frontal area is backed by this study.
It includes the assertion that helmets are an essential safety aid, so clear
evidence of bias. There is also no mention of the helmets tested meeting
ANSI standards; it would be a surprise if they did.
>
http://www.gssiweb.com/reflib/refs/28/d0000000200000069.cfm?pid=96&CFID=807492&CFTOKEN=69087813
Barely refers to helmets (the word appears precisely twice). Quote: "In
cycling, riders wear aerodynamic helmets and skintight clothing and assume
crouch positions over the handle bars ("aero bars") to minimize wind
resistance". No figures presented, no analysis undertaken. Refers solely
to aero helmets for time trial and track racing.
> http://sportsfigures.espn.com/sportsfigures/batting_quiz4.htm
A children's pop quiz also referring to head fairings. No academic weight
whatsoever.
> http://wings.avkids.com/Curriculums/Sports/cyclist_summary.html
A school science project, no new data, no academic weight, merely restates
Kyle: "An aerodynamic bicycle helmet reduces the drag by approximately 2%
over a rider with no helmet. In fact, modern aerodynamic helmets result in a
lower drag even for a bald bicyclists." - in other words, yet again, it's
about head fairings.
> http://www.gugly.com/Archbikeclothing.htm
"The difference between good and bad helmets has been shown in studies to be
equivalent to the difference between a good disc wheel and a standard 36
round spoke, box shaped rim wheel (at about 30 mph)." - aero helmets again.
No academic weight, no new data, no analysis, just parroting the same
figures which (as we know) have been show ion practice to be optimistic even
for those highly specialised hlemets. Dates back to the days of head
fairings,
Also contains this gem: "Good helmets are designed to work effectively when
the rider is facing forward and not to the side. Doing so, will not only
eliminate all benefits gained with the good helmet, but may also slow you
down. And for those who still can't picture what I'm saying, turning you
head while using an aerodynamic helmet is like trying to cut a piece of
butter with the knife laying on its side rather than on its edge."
> http://www.ul.ie/~childsp/Elements/issue2/sharpe.html
Contains precisely one mention of helmets: "Wind-suits and helmets, together
with streamlining the bicycle, and the rider adopting a low profile riding
posture can reduce drag by up to 7%" - on other words, yet again, they are
talking about top-spec time trial or (in this case) pursuit kit. In this
case the fact that it is track kit under discussion is made plain by the
inclusion of the Burrows Lotus bike ("Olympic gold medalist Boardman's Lotus
bicycle [...] under 6kg compared to a conventional track bicycle weight of
over 8kg"), which of course the UCI promptly banned.
Bill, this is desperate stuff. Is this the best you can do?
> rest of post snipped - it's time for dinner, so your remaining post
> today gets ingnored as well.
Translation: "Laa laa I'm not listening"
Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk
88% of helmet statistics are made up, 65% of them at Washington
University
Every one of the links you posted referes solely to aero helmets. Those
which quote actual figures, the first one excepted, are all based on the
same study - and it's the same figure as in Rinard's piece
(http://damonrinard.com/aero/aerodynamics.htm), so comes from
the original Kyle paper as already discussed ad nauseam. Maybe it's time to
resurrect the old nickname "Bill *only-one-study-in-only-one- country*
Zaumen"! Just to remind you
of the context of the 2% figure which is the only number quoted in all but
one of the studies you link:
"Aero helmets, as they are used for racing, which do not
however meet the ANSI safety requirements, reduce the
aero drag by approximately 2% compared to a bald head or
a rubber cap over the hair. "
All of this is obvious to the casual reader, indicating that you probably
did not go further than the Google summaries.
So now to the links:
<http://www.mecheng.adelaide.edu.au/courses/undergrad/projects/level4papers2
001/chin_lim.pdf>
"Design of an aerodynamically sound bike helmet" - i.e. a theoretical paper
on how to remedy the fact that bike hlemets are /not/ aerodynamically sound.
Quote from abstract: "helmet will increase the frontal area of the rider's
head and this will affect the aerodynamics of the rider, thus, the rising of
drag. Therefore, helmet must have a good aerodynamics shape to minimise the
effect of the frontal area. Two track cycling helmets are used to
investigate the performances of drag in different position."
So Frank's comment re greater frontal area is backed by this study.
It includes the assertion that helmets are an essential safety aid, so clear
evidence of bias. There is also no mention of the helmets tested meeting
ANSI standards; it would be a surprise if they did.
>
http://www.gssiweb.com/reflib/refs/28/d0000000200000069.cfm?pid=96&CFID=807492&CFTOKEN=69087813
Barely refers to helmets (the word appears precisely twice). Quote: "In
cycling, riders wear aerodynamic helmets and skintight clothing and assume
crouch positions over the handle bars ("aero bars") to minimize wind
resistance". No figures presented, no analysis undertaken. Refers solely
to aero helmets for time trial and track racing.
> http://sportsfigures.espn.com/sportsfigures/batting_quiz4.htm
A children's pop quiz also referring to head fairings. No academic weight
whatsoever.
> http://wings.avkids.com/Curriculums/Sports/cyclist_summary.html
A school science project, no new data, no academic weight, merely restates
Kyle: "An aerodynamic bicycle helmet reduces the drag by approximately 2%
over a rider with no helmet. In fact, modern aerodynamic helmets result in a
lower drag even for a bald bicyclists." - in other words, yet again, it's
about head fairings.
> http://www.gugly.com/Archbikeclothing.htm
"The difference between good and bad helmets has been shown in studies to be
equivalent to the difference between a good disc wheel and a standard 36
round spoke, box shaped rim wheel (at about 30 mph)." - aero helmets again.
No academic weight, no new data, no analysis, just parroting the same
figures which (as we know) have been show ion practice to be optimistic even
for those highly specialised hlemets. Dates back to the days of head
fairings,
Also contains this gem: "Good helmets are designed to work effectively when
the rider is facing forward and not to the side. Doing so, will not only
eliminate all benefits gained with the good helmet, but may also slow you
down. And for those who still can't picture what I'm saying, turning you
head while using an aerodynamic helmet is like trying to cut a piece of
butter with the knife laying on its side rather than on its edge."
> http://www.ul.ie/~childsp/Elements/issue2/sharpe.html
Contains precisely one mention of helmets: "Wind-suits and helmets, together
with streamlining the bicycle, and the rider adopting a low profile riding
posture can reduce drag by up to 7%" - on other words, yet again, they are
talking about top-spec time trial or (in this case) pursuit kit. In this
case the fact that it is track kit under discussion is made plain by the
inclusion of the Burrows Lotus bike ("Olympic gold medalist Boardman's Lotus
bicycle [...] under 6kg compared to a conventional track bicycle weight of
over 8kg"), which of course the UCI promptly banned.
Bill, this is desperate stuff. Is this the best you can do?
> rest of post snipped - it's time for dinner, so your remaining post
> today gets ingnored as well.
Translation: "Laa laa I'm not listening"
Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk
88% of helmet statistics are made up, 65% of them at Washington
University