Conference noted::bicycle

    No, I didn't have this happen to me but I was there when it happend.
    
    I was out riding my dirt-bike (The one with the motor) when I came
    across a bunch of Yahhoo's on ATC's (also known as three wheelers)
    Out of the five of them two had helmets, the others had baseball
    hats on backwards. They stopped and said that they were going down
    a trail I knew had a huge washout across it, about six feet deep
    and maybe fourteen across. I asked them if they knew about the washout
    and they told me they did. Off they flew down the trail with me
    eating dirt in the back of the pack. When they approached the 1/3
    sized Grand Canyon they didn't slow down. I held my breath as they
    went off the edge. Some how the first guy made it, but the second
    didn't. I saw his trike fly out of this big dust cloud, his helmet
    went the other way. The rest of them stopped in time. Well the guy
    got up and was walking around asking what happend, we told him.Then
    he asked where he was, we told him the sand pits in Oxford. Then
    he asked where Oxford was? Well we looked at each other and one
    of his friends starts humming the theme from Other Limits. Oxford
    thats his home town...
    
    	Two weeks later I saw that bunch out riding. The guy with the
    head injury was not wearing the yard sale special helmet he had
    on that day, the one without the chin strap. He had the top of the
    line Bell $150. So didn't the rest of them.
    
    	As far as not remembering what happend you will remember after
    time if it was not to big of a bang. It'll come back to you and
    it'll be like recalling a dream or something that happend a long
    time ago, even if it just happend two days ago.

    I have experienced short term memory loss after this type of accident.
    My physician tells me it is nothing to be concerned about. However,
    if you still don't remember your name, address, etc. after a few
    weeks, well...
    
    Seriously, take the time to have the helmet inspected by Bell. Not
    only should the liner be replaced, they are good for one fall only,
    but the structural integrity of the shell should be examined by
    the manufacturer. There may well be some damage that is not obvious
    to you. Double check the three points where the chin strap is attached
    to the helmet. Both my friend and I have experienced structural
    failure in the V1 Pro at this point after an accident.
    
    I don't believe Bell still replaces the liners gratis. Please let
    the conference know if you find out differently.
    
    Glad to hear you are allright!

    	I just saw a listing of effects as a function of g forces and
    I can't remember where it was - either here or in the UseNet bike
    file.  I do remember the numbers though: effects start at about
    100 to 150 g's and becomming more drastic as 700 g's are approached.
    
    These seem like awfully high numbers (I know whole body g forces
    are more in the 30 to 50 range for survivable auto crashes) so I
    did the math:  Assume a velocity and a distance to stop, calculate
    the required g force.  The velocity can be vertical (a fall from
    5 feet hits the ground at about 17 feet/sec) or horizontal - your
    speed over the road.  Actually, it's a vector sum of the two with
    the angle of impact making the total less severe.  But say the impact
    happens at at least 20 ft/sec (about 14 mph).  The distance to stop
    is called the crush distance in safety engineeting. How far the
    front end of the car is pushed back, if that is what takes the blow,
    or how much the liner of your helmet crushes (momentarily) is that
    is all that is between your head and what it hits.  I would think,
    given the resiliance of the skull, that .1" would be a minimum for
    impact with no helmet, and that a helmet liner would go to at least
    .5" of crush.  Given these, here's the results:
    
    velocity in ft/sec		crush dist. in inches          g force
    -------------------------------------------------------------------
    20		no helmet	.1			1240 !
    20		w/helmet	.5			310
    
    30		w/helmet	.5			700
    
    again, remember, the above are for a full stop impact whereas a
    glancing bounce { X sin(angle) } is more typical.
    
    Has anyone got a copy of the effects vs. g force table?  Could you
    point or post it?  - Chris
    

The following is from the rec.bicycling USENET conference, as
part of a long thread (never-ending) on helmets.

Dave

----------------------------------
 
The following data is derived from:
Joe Minton, "A Head of the Game," _Bicycle Rider_, Spring 1985, pps 110-117.
 
Trauma to the brain may be classified by the number of g's absorbed by
the brain on impact.
 
less than 150 g's: Little or no injury.
 
150-250 g's:  Light concussion and traumatic amnesia--no memory of the
              accident,and possible loss of several previous hours.
 
250-350 g's:  Loss of conciousness for several minutes.  More pronounced
              amnesia with possible loss of some events from long term
              memory.  Possible permanent damage at the higher end.
 
400-700 g's:  Bruising, laceration and hemorrhage of the brain.  Survival
	      is dependent on expert care; permanent brin damage is 
              probable.
 
greater than 700 g's:  Survival is unlikely.  Survivors will incur 
                       "permanent and significant brain damage."
 
 
No big deal, right?
 
The article goes on to say that a typical fall of 5.3 feet over the
handlebars occurs at a speed of 0.574 g-seconds and a velocity of 12.5
mph.  Because, in a head first fall, the head stops its motion in a
very short distance (say about 0 inches), and in a short period of time
(say 0.5 milliseconds), the force incurred exceeds 1000 g's!
 

    The impact DID crush a section of the old helmet liner. I pointed that
    out to my wife (rehab. nurse for the head injured, coincidentally)
    and we both said a prayer of gratitude that night. I have bought a 
    new Bell V1 Pro and have continued my training after a few days off. 
    Judging form the chart the impact to my brain was around 100 to
    150 G's, judging the effects listed and my symptoms. I lost a few
    minutes before, the whole accident, and parts of the next hour or
    two.
    
    I feel FEAR when I go over the calculated spot where I think I fell.
    My body seems to know what happened, but my mind keeps the details
    from me. I won't be too certain if I ever remember the event. 
    
    Thanks for everyone sharing their or others experiences. I will
    prob'ly send the helmet to Bell and post the reply in this note
    later.
    
    On a different note, I'm hoping to hit my targeted training goal of 
    a Century by Oct. 1 in 6 hours and ENJOY it. So far, I've done 100 - 
    125 mi./week for 9 weeks. My longest trip has been 50 mi. in 3 hours. 
    I'm going to do a 65 miler this weekend and try to see if I can do the 
    century the next weekend. Wish me luck.
    
    				Russ

    
    	i)	Don't worry any more about the helmet
    	ii)	Don't worry about the physics involved.
    	iii)	DO worry about your self and your possible injury. 
    Get THOROUGHLY checked out, INSIST on a full set of diagnostic
    procedures, catscans, whatever.  Don't take head jolts lightly,
    answering simple questions about your name and address is only a
    rough guide to whether you are functioning, but you could still
    have damage that isn't obvious.  With all due respect to your wife,
    and her profession, have a thorough medical examination, SOOOOOON !
    There are just too many possible complications from delayed
    concussion to take ANY chances.
    
    	Reg	{Wishin' Ya well}
    
    
    
            

    I was in a accident last year and sent my helmet in to Bell.
    They're in Rantoul, Illinois and they're about the only thing in
    Rantoul.  They did not replace the styrofoam inside the TourLight
    but they did say the helmet was undamaged other than some scratches.
    It takes about 10 days and as I remember they paid for the return
    postage. _KB

    My wife suggested the CaT scan and exam that same day. She expalined
    that even though I was fully alert and recognized everything (except
    what day it was for a few hours), she was pushing me to go foir
    the CaT scan. We are getting the doctor's opinion tonight.
    
    I never thought it was necessary at first, but we'll see what the
    doctor advises and then make our decision. Thanks efor the GOOD
    advise, Reg! Maybe I can get a good deal on a used noggin'. I know
    a lot of people that said they'd gladly give me a piece of there
    mind for free! &^)
    
    					Russ

    A friend of mine had a loss of short-term meory ability after a bike
    accident. He showed up at the restaurant where he was meeting some
    people, sans bike. He said, "I think I was in an accident", asked "Have
    you seen my bike?", and some other questions, which they answered. A
    few minutes later he said, "I think I was in an accident", and went
    through the same litany of questions. After several rounds of this
    someone called a physician, and got some advice on observing him. The
    rest of the people made up a card with the answers to his questions. As
    soon as he started the spiel again, he noticed the card and read the
    answers to the questions as they came to him. He found it quite
    fascinating, over and over again.
    
    After dinner someone took him home to watch him, and recorded his
    questions and the answers to them on a tape recorder. When he started
    from the beginning again, he was asked to play the tape. He found
    it fascinating, over and over again. Eventually after several hours
    the memory problem wore off. It's a good enough story that's he's
    presented it several times as a lecture.
    
    Moral: People in this state are easily amused.
    
    --Dan

    I lost a few hours in junior high schools when I was playing goalie in
    team handball and was screen on a shot.  I think I played the rest of
    the game, although I don't remember it.  I remember having some trouble
    with my locker combination, but got it open in the end.  The next thing
    I remember is shortly after dinner that evening. There was a big blank
    spot in my memory which should have been occupied byu the bus ride
    home, walking home from the bus stop, and everything at home up to
    dinner.  It's definitely a strange sensation to lose a chunk of your
    life,  but if the doctor gives you a clean bill of health, I wouldn't
    worry about it.  I've noticed no permanent effects from my incident,
    although I did notice that everyone else was a little stranger
    aftwerwards. :-) 

    Tom

    Well according to some of the previous notes I should at least be
    brain dead by now (no wise cracks REG please).
    
    Back nine years ago I was involved in an accident while out training.
    I can tell this by the circumstancial evidence, not by any recollection
    that I have of the events. I was not wearing a helmet. Practically
    nobody here in Ireland wears a helmet. Without going into the
    mechanical niceties of what happened suffice it to say that the
    mudguard acted as a brake and I was thrown off with sufficient
    force to destroy the wheel and forks and slightly buckle the frame.
    I was likely doing 20 MPH when the accident occurred.
    
    I was out cold for over an hour. I woke up in hospital as they were
    stitching my face back together (literally). I didn't know who I
    was, where I was , Who my training partner was, who my two sisters
    who had arrived at the hospital were, etc. It took about another
    2 hours before even this basic data began to register. It was weird
    though I'm sure it was funny for the onlookers. What was really
    frustrating was my inability to express myself properly. At times
    my mind  knew what I wanted to say but couldn't get my mouth to
    say it. 
    
    For about one hour after coming around the same image kept coming
    back into my mind of a new album by THE CARS rock group that I had
    heard for the first time that evening. I would mumble something
    about the cars (I'm sure many times over) and everyone present assumed
    I was talking about the accident. I couldn't coordinate myself enough
    to say what I was really talking about.
    
    I still have no memory about the accident but regained my memory
    of things up to 5 minutes before the accident. I have no fear as
    I cannot remember anything about it. I have only this year started
    to wear a helmet as a result of doing a few triathlons (it's
    compulsory).
    
    So why am I not dead if all this G force stuff is right ?
    
    See ya
    
    John

< Note 871.12 by DUB01::OSULLIVAN >
               -< WANTED: New liner for slightly damaged skull >-

>    So why am I not dead if all this G force stuff is right ?
    
You were VERY lucky.  The fact that you are alive does not prove that the "G 
force stuff" is wrong, only that some particular details of your accident 
saved your life.  It is incomprehensible that you could come so close to 
death, and still not wear a helmet.  Or is this evidence of lingering brain 
damage?  :^)

    Without wishing to start a helmet/no-helmet rathole, I think the reason
    that people don't wear helmets here in the UK and Ireland is because
    they never have - it's cultural. 
    
    I get the impression from Bicycle Notes that cycling as a serious mass
    leisure pursuit in the US is a fairly recent phenomenon. So perhaps
    there's no mass of tradition behind US cyclists that shapes the way
    they approach cycling, which means they'll quickly start making their
    own traditions. One of which is to alway wear a helmet. 
    
    In the UK and presumably Ireland too, people still stand out if they
    wear a helmet. That said, I'm seeing more now, and I think more and
    more cyclists will go over to wearing them.
    
    No, I don't wear one.
    
    Rod 

>< Note 871.14 by RDGENG::MACFADYEN "Roderick MacFadyen" >

>    In the UK and presumably Ireland too, people still stand out if they
>    wear a helmet. 

     Yes, imagine being confronted (as I have been) by giggly, pointing-
     fingered natives of all ages not only in the UK, but also in Europe.
     And you'd better believe the old-style "Spaceballs" Bell helmet
     stands out in a crowd.  Made a real hit in DECpark last week, too.

     -john

    Another memory loss story:
    
    My husband and I were riding a trail around Monarch Pass in Colorado
    at the end of August, and toward the end of the ride he took a bad
    fall and knocked himself out.  No one saw it happen, but I found
    him.  His Bell V1 Pro liner had compressed and cracked where his
    head had hit the ground.
    
    Luckily that section of the ride was on a 4-wheel-drive road, so
    it only took an hour and a half from the time of the accident until
    he was in the emergency room of the Salida hospital.
    
    He can remember pretty much everything up to the accident, but he
    still has no idea what happened.  He remembers thinking "this is
    going to hurt", and assumes that was right before the crash.
    
    He slept about 20 hours/day for a week, and can't remember much
    of anything from that entire week.  He still has trouble remembering
    names sometimes.
    
    His co-workers gave him a gift certificate for a new helmet as a
    get-well gift.  He went on a ride two weeks after the accident,
    and went over the handlebars and hit his head again.  But he got
    right back up and took off riding again - he said it gave him his
    confidence back, to find out he could crash and NOT end up unconscious!
    
    Does anyone know if this problem of not remembering names will go
    away eventually?
    
    - Diane

It sounds as though his accident was similar to mine, as I described in the
base note. The difference is that his sounds as though it involved more force.
The Bell V1 Pro also was my head's protector.

In my situation, my memory came back pretty well. I was not unconscious
right after, as far as I know. My only difficulty was occassionally for
about a week after the fall, I had to search for a word or two that I just
couldn't grab. On those few occassions, I knew the object but couldn't get
the word out.

In his case, I hope a brain scan was taken while at the hospital. It's still not
too late to check for any irregularity. That scan would give an indication of
any irregular brain activity. This is what my wife says who specialized as a
nurse in that field of medicine.

I think the best people to set answers with some degree of certainty are
the doctors. 
    
				Russ