Helmets move on from fashion to technological safety improvements, at last.

Helmets move on from fashion to technological safety improvements, at last. Always wanted to know what MIPS is? See: http://www.chainreactioncycles.com/i...e_tech_%281%29

On Sunday, May 3, 2015 at 1:40:21 PM UTC-4, Andre Jute wrote:
Helmets move on from fashion to technological safety improvements, at last. Always wanted to know what MIPS is? See: http://www.chainreactioncycles.com/i...e_tech_%281%29

YOU SHOULD WEAR ONE

On Sunday, May 3, 2015 at 6:51:36 PM UTC+1, wrote:
On Sunday, May 3, 2015 at 1:40:21 PM UTC-4, Andre Jute wrote:
Helmets move on from fashion to technological safety improvements, at last. Always wanted to know what MIPS is? See: http://www.chainreactioncycles.com/i...e_tech_%281%29

YOU SHOULD WEAR ONE

One has to wonder if my netstalker Jeff Daniels ) ever sleeps or shops or showers. I post a new thread and seconds later, invariably, this clown posts a wannabe disruption. Here, 20 SECONDS after I sent my post, poor Daniels is on my case.

Yo, Daniels, it is permitted for you to take time off for a shower and to brush your teeth. People might like you better, then.

Andre Jute
The killer comma

I wuza eatin' lunch....fresh squid in chilled tomato sauce with a light vermouth on the rocks...breaking from grille maintenance.

I am now entering an accounting phase with a snack break, OJ with guarine and an ahhhpricot Cliff bar.

Found another body seam tube refinished...now holding sand from above The Yearling set at Pats Island

I haven't read your latest drivel.

how many reasons are there for a helmet ? I have a nice one a Bell on sale. Wearing it is like driving down the Interstate in muh 544.

PITA

1. you have previous crashed therefore...(unlikely)

2. there's Birdy...I didnah know he's into helmets....he's giggling.

ahhh I ben trying to get photography on this Birdy and scored just now with a vocalizing video. Super. I believe he just got laid. The elder Birdy showed up 2 hours ago with his girlfriend for a snack. Speaking Grackles are slightly different physically than not speaking or seldom speaking grackles tho both are in the same family.

lets see

2. THE GOVERNING BODY requires helmets

3. Your mother requires helmets

4. you rational chose a helmet for protection

a. MTB
b. half pipe

c. on so forth......

the only helmets we see here are in the peloton, an organized ride comes by our front lawn.

On Sunday, May 3, 2015 at 4:53:05 PM UTC-4, wrote:
I wuza eatin' lunch....fresh squid in chilled tomato sauce with a light vermouth on the rocks...breaking from grille maintenance.

I am now entering an accounting phase with a snack break, OJ with guarine and an ahhhpricot Cliff bar.

Found another body seam tube refinished...now holding sand from above The Yearling set at Pats Island

I haven't read your latest drivel.

how many reasons are there for a helmet ? I have a nice one a Bell on sale. Wearing it is like driving down the Interstate in muh 544.

PITA

1. you have previous crashed therefore...(unlikely)

2. there's Birdy...I didnah know he's into helmets....he's giggling.

ahhh I ben trying to get photography on this Birdy and scored just now with a vocalizing video. Super. I believe he just got laid. The elder Birdy showed up 2 hours ago with his girlfriend for a snack. Speaking Grackles are slightly different physically than not speaking or seldom speaking grackles tho both are in the same family.

lets see

2. THE GOVERNING BODY requires helmets

3. Your mother requires helmets

4. you rational chose a helmet for protection

a. MTB
b. half pipe

c. on so forth......

the only helmets we see here are in the peloton, an organized ride comes by our front lawn.

http://hkcyclingalliance.org/wp-cont...on-268x300.gif

On Sun, 3 May 2015 10:40:19 -0700 (PDT), Andre Jute
wrote:

Helmets move on from fashion to technological safety improvements, at last. Always wanted to know what MIPS is? See: http://www.chainreactioncycles.com/ie/en/r-pl/the-lab

MIPS is a patent licensing organization in Sweden. They've been
working improving bicycle helmets since about 2001.
http://www.mipshelmet.com
What seems to be missing is an explanation of how a 5 mm fore-aft
sliding motion is suppose to reduce rotational injuries. I also can't
seem to find any testing data:
https://www.google.com/#q=mips+bike+helmet+testing
http://www.bhsi.org/mips.htm
Assuming I haven't missed anything, it appears that the move from
"fashion to technological safety improvements" is a marketing gimmick.

Now, if you want a real safety helmet, you have to make some
concessions. The helmet has to be single use and ablative (sheds mass
on impact). Let's play with the numbers. Your head is about 8% of
body mass of 80 Kg = 6.4 kg. When you slam into the pavement at
speed, the kinetic energy is:
E = 0.5 mv^2 = 0.5 * 6.4 kg * (5 meters/sec)^2 = 80 KJoules
If the helmet is expect to reduce the impact force to zero, some mass
will need to ablate (fly way) from the helmet in order to balance the
forces. For example, if your helmet contained 500 ml of water in a
bag, which exploded on impact, the energy would go with the water,
thus reducing the energy transferred to the head. The water will fly
off at:
v = E / 0.5 / m^0.5
v = (6400/500)^0.5 * 5 m/sec = 16.4 m/sec (about 37 mph)
which is barely reasonable.

The problem is that the water must come from the side of the head
opposite the impact, which implies that far more than 1kg of water is
required. Ablated water flying off perpendicular to the direction of
impact isn't going to do much. 1kg of water occupies 1 liter so a
refillable water helmet is likely to be seriously large and overweight
especially compared to a 300 gram helmet.

Another problem is that launching 500 mg of water from the side
opposite the impact implies that the energy of impact has to either go
through the head or around the head and through the helmet. Obviously,
going through the head is undesirable, so the helmet will need to
transfer the force. That's done by placing the water bag on the side
of impact, plumbing the water through tubes to the opposite side, and
ejecting the water. That's not going to be easy unless the plumbing
is large. If there's any back pressure, the water will transfer the
force to the head instead of ejecting. Pressurized air assist might
help.

You can adjust the amount and distribution of the water bags, but
basically that's what it takes to build an ablative bicycle helmet.
One also doesn't need to reduce the transferred energy to zero, but
it's a convenient target value for comparisons.

Another method is to redirect the forces over a larger area, better
able to withstand them. For example, a helmet that mounts onto the
shoulders will transfer much of the impact to the shoulders and away
from the head. The shoulders aren't the strongest part of the body,
but they're better than the neck at absorbing torsional forces.

There's another problem. The consensus is that a smooth hard shell is
best because to prevent snagging on things as your head goes skidding
across the pavement or dirt. That's true as a snag could easily break
your neck. Yet, for the standpoint of absorbing force, you want the
foam helmet to shed as it skids down the road, absorbing the forces by
ripping itself apart. Ideally, such a helmet would be a rather large
diameter, open cell foam, made from something hard, like urethane. It
would ablate and get hot, but since it's also thin and hard, would not
snag as much.

So what does a real safety helmet look like? A giant urethane
puff-ball, with strategically placed water bladders, some hoses for
air assisted water ejection, a neck brace, and shoulder mounts. It
would weight 5kg, double one's air resistance, and lack any form of
cooling. It would be uncomfortable, unusable, intolerable, but you
would be safe.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thanks, Jeff. The quality of engineering that you do at the drop of a hat (oops!) is humbling.

Andre Jute

On Sunday, May 3, 2015 at 11:17:27 PM UTC+1, Jeff Liebermann wrote:
On Sun, 3 May 2015 10:40:19 -0700 (PDT), Andre Jute
xx wrote:

Helmets move on from fashion to technological safety improvements, at last. Always wanted to know what MIPS is? See: http://www.chainreactioncycles.com/ie/en/r-pl/the-lab

MIPS is a patent licensing organization in Sweden. They've been
working improving bicycle helmets since about 2001.
http://www.mipshelmet.com
What seems to be missing is an explanation of how a 5 mm fore-aft
sliding motion is suppose to reduce rotational injuries. I also can't
seem to find any testing data:
https://www.google.com/#q=mips+bike+helmet+testing
http://www.bhsi.org/mips.htm
Assuming I haven't missed anything, it appears that the move from
"fashion to technological safety improvements" is a marketing gimmick.

Now, if you want a real safety helmet, you have to make some
concessions. The helmet has to be single use and ablative (sheds mass
on impact). Let's play with the numbers. Your head is about 8% of
body mass of 80 Kg = 6.4 kg. When you slam into the pavement at
speed, the kinetic energy is:
E = 0.5 mv^2 = 0.5 * 6.4 kg * (5 meters/sec)^2 = 80 KJoules
If the helmet is expect to reduce the impact force to zero, some mass
will need to ablate (fly way) from the helmet in order to balance the
forces. For example, if your helmet contained 500 ml of water in a
bag, which exploded on impact, the energy would go with the water,
thus reducing the energy transferred to the head. The water will fly
off at:
v = E / 0.5 / m^0.5
v = (6400/500)^0.5 * 5 m/sec = 16.4 m/sec (about 37 mph)
which is barely reasonable.

The problem is that the water must come from the side of the head
opposite the impact, which implies that far more than 1kg of water is
required. Ablated water flying off perpendicular to the direction of
impact isn't going to do much. 1kg of water occupies 1 liter so a
refillable water helmet is likely to be seriously large and overweight
especially compared to a 300 gram helmet.

Another problem is that launching 500 mg of water from the side
opposite the impact implies that the energy of impact has to either go
through the head or around the head and through the helmet. Obviously,
going through the head is undesirable, so the helmet will need to
transfer the force. That's done by placing the water bag on the side
of impact, plumbing the water through tubes to the opposite side, and
ejecting the water. That's not going to be easy unless the plumbing
is large. If there's any back pressure, the water will transfer the
force to the head instead of ejecting. Pressurized air assist might
help.

You can adjust the amount and distribution of the water bags, but
basically that's what it takes to build an ablative bicycle helmet.
One also doesn't need to reduce the transferred energy to zero, but
it's a convenient target value for comparisons.

Another method is to redirect the forces over a larger area, better
able to withstand them. For example, a helmet that mounts onto the
shoulders will transfer much of the impact to the shoulders and away
from the head. The shoulders aren't the strongest part of the body,
but they're better than the neck at absorbing torsional forces.

There's another problem. The consensus is that a smooth hard shell is
best because to prevent snagging on things as your head goes skidding
across the pavement or dirt. That's true as a snag could easily break
your neck. Yet, for the standpoint of absorbing force, you want the
foam helmet to shed as it skids down the road, absorbing the forces by
ripping itself apart. Ideally, such a helmet would be a rather large
diameter, open cell foam, made from something hard, like urethane. It
would ablate and get hot, but since it's also thin and hard, would not
snag as much.

So what does a real safety helmet look like? A giant urethane
puff-ball, with strategically placed water bladders, some hoses for
air assisted water ejection, a neck brace, and shoulder mounts. It
would weight 5kg, double one's air resistance, and lack any form of
cooling. It would be uncomfortable, unusable, intolerable, but you
would be safe.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sun, 03 May 2015 15:17:31 -0700, Jeff Liebermann
wrote:
(...)

I skipped a step and should have mumbled something about inelastic and
elastic collisions, which is another mechanism at work.

There are two collision involving a helmet. The helmet hitting the
ground (or if you will, the ground hitting the helmet), and the helmet
hitting the head. I don't want to get into the brain banging around
inside the skull quite yet. If the masses involved in the collision
stick together, it's considered inelastic. If they bounce off each
other, it's elastic.
http://www.schoolphysics.co.uk/age14-16/Mechanics/Forces%20in%20motion/text/Trolley_collisions/index.html
Note that the trolley in the lower animation move at a much slower
speed than the impacting trolley when the two are stuck together.

The big question is whether to make the helmet smooth and hard, or
soft and spongy. A hard helmet will act like the middle animation.
Hit a hard surface and all of the energy of the collision is
transferred to the helmet and then to the head. A soft helmet will
act like the lower animation, where during the time when the two
objects are connected, the sum of the masses produces a much reduced
final velocity.

If you are unlucky enough to have your hard helmet hit by a baseball
bat wielding motorist, the situation will look like the top animation,
where the change in direction of the rebounding baseball bat, actually
increases the momentum transferred to roughly twice the middle
animation. What you really want is a soft helmet, that captures the
mass of the baseball bat, which reduces the final velocity of the
combined helmet, head, and baseball bat.

However, a hard shell helmet has one big advantage. It can
redistribute the force of impact over a much larger area. When hit at
one point, the force follows along the hard shell and eventually
dissipated into the underlying foam and padding. None of the energy
has been lost through ablation, but because it's spread over a larger
area, does less damage. That's roughly how a football helmet works.
However, in bicycle helmets, the hard shell is often extremely thin
and thus unable to redirect the force of impact. At best, it does
hold the foam in place and looks artistic. Fortunately, there are
hard shell bicycle helmets available:
https://www.google.com/search?q=hard+shell+bicycle+helmet&tbm=isch

The ideal helmet would probably be a combination of hard shell, water
ablation, and collapsible foam padding. In my deranged mind, I see a
helmet that looks and acts like a fragmentation grenade. When hit on
one side, the energy is transferred across the hard surface to the
opposite side through connecting hoses, where it blows off a water
bladder to help dissipate the force of impact. Add neck and shoulder
braces and the bicycle helmet of the future has arrived.





--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

This one would look good on a deranged cyclist like Franki-boy, and keep him from doing harm to himself when he takes the lane, probably by stopping him cycling altogether if not from weight then from embarrassment:

The ideal helmet would probably be a combination of hard shell, water
ablation, and collapsible foam padding. In my deranged mind, I see a
helmet that looks and acts like a fragmentation grenade. When hit on
one side, the energy is transferred across the hard surface to the
opposite side through connecting hoses, where it blows off a water
bladder to help dissipate the force of impact. Add neck and shoulder
braces and the bicycle helmet of the future has arrived.

If I could have some useful additional safety for only a few ounces added to my Bell Citi and Metro helmets, I would not begrudge the extra weight, as those helmets do seem very light.. Where should the few ounces most usefully be applied? Some kind of a HANS device?

Also, as several of my professors used to say not because they were pretentious but because they were German or Dutch (business schools in particular are overrun with Dutch applied economists). What about that neck ruff that blows up into a helmet in a milisecond on sensing an impact that was mentioned here a few months ago? Air has an admirable balance of absorption and displacement, or so automobile suspension experts always reckon.

Andre Jute
Fascination, I know...

On Monday, May 4, 2015 at 1:44:00 AM UTC+1, Jeff Liebermann wrote:
On Sun, 03 May 2015 15:17:31 -0700, Jeff Liebermann
wrote:
(...)

I skipped a step and should have mumbled something about inelastic and
elastic collisions, which is another mechanism at work.

There are two collision involving a helmet. The helmet hitting the
ground (or if you will, the ground hitting the helmet), and the helmet
hitting the head. I don't want to get into the brain banging around
inside the skull quite yet. If the masses involved in the collision
stick together, it's considered inelastic. If they bounce off each
other, it's elastic.
http://www.schoolphysics.co.uk/age14-16/Mechanics/Forces%20in%20motion/text/Trolley_collisions/index.html
Note that the trolley in the lower animation move at a much slower
speed than the impacting trolley when the two are stuck together.

The big question is whether to make the helmet smooth and hard, or
soft and spongy. A hard helmet will act like the middle animation.
Hit a hard surface and all of the energy of the collision is
transferred to the helmet and then to the head. A soft helmet will
act like the lower animation, where during the time when the two
objects are connected, the sum of the masses produces a much reduced
final velocity.

If you are unlucky enough to have your hard helmet hit by a baseball
bat wielding motorist, the situation will look like the top animation,
where the change in direction of the rebounding baseball bat, actually
increases the momentum transferred to roughly twice the middle
animation. What you really want is a soft helmet, that captures the
mass of the baseball bat, which reduces the final velocity of the
combined helmet, head, and baseball bat.

However, a hard shell helmet has one big advantage. It can
redistribute the force of impact over a much larger area. When hit at
one point, the force follows along the hard shell and eventually
dissipated into the underlying foam and padding. None of the energy
has been lost through ablation, but because it's spread over a larger
area, does less damage. That's roughly how a football helmet works.
However, in bicycle helmets, the hard shell is often extremely thin
and thus unable to redirect the force of impact. At best, it does
hold the foam in place and looks artistic. Fortunately, there are
hard shell bicycle helmets available:
https://www.google.com/search?q=hard+shell+bicycle+helmet&tbm=isch

The ideal helmet would probably be a combination of hard shell, water
ablation, and collapsible foam padding. In my deranged mind, I see a
helmet that looks and acts like a fragmentation grenade. When hit on
one side, the energy is transferred across the hard surface to the
opposite side through connecting hoses, where it blows off a water
bladder to help dissipate the force of impact. Add neck and shoulder
braces and the bicycle helmet of the future has arrived.





--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Lieb

all impacts are rotational

ablation ? heat generated by cushioning absorption thru impact shrinking as Bell et all..

no reason...eyeyyhhaha pick one....for a hard shell Bell covered with a replaceable shredder covering.

shredding is good at bike speeds. My tights shred n I walk away untorn. Good stuff.

you remember my account of the first corner at Bloomsburg Crit ? Jungle Gym pile up, rider fell in front of me head snacking with a crack occipital right on the curb. He got on n rode off.
f(B)

helmet protection stand on energy absorption research n production....for areas other than bike helmets. Asking if FIA absorption is used in bike helmets ?