Conference noted::bicycle

    Neither ANSI  nor  Snell  tests  helmets  in  this  way,  so it is
    entirely  possible that they will fail when they hit a sharp edge.
    (ANSI  and Snell test on a flat surface, and a convex one. There's
    also  a "Dart" test, which drops a pointed dart on the helmet, but
    I'm not sure if it's in the standard.)

    The real  issue  is  what  forces  were  involved. Helmets are not
    supposed  to  survive  an  impact,  but  it  is  nice if they stay
    together  well  enough  to  provide  some protection if there is a
    second  impact  in  one accident (bounce off the car, then hit the
    street).  The  helmet is supposed to limit the acceleration of the
    head  during an impact, and it's not clear that splitting prevents
    this.

    Can you get a copy of the original report?

--David Wittenberg

    	I thought that helmets were SUPPOSED to take the force, sparing the
    head.  The Snell foundation and ANSI test how many grams of force would 
    be applied to a skull within a helmet, rather than how the helmet itself 
    holds up.   A steel infantry helmet wouldn't shatter, but neither would
    it offer much protection from the force of a crash.  Which do you want
    to survive a crash, the head or the helmet? (Rhetorical question, please 
    don't answer.)
    
    	There is always the possibility that this consumer magazine is onto 
    something, but it seems more likely that they are less than expert in 
    designing helmet experiments. 

    This report caught my eye, because I have a Specialised Airforce 1.
    The method of testing, as far as I can gather, was that they stuck an
    object the size and weight of a head into a helmet, then dropped it
    from some height - a metre? - onto the kerb of a road. They seem to
    have based their conclusions on how well the helmet survived the test.
    
    The test seems questionable. It's brutally simple, and must mimic a
    real crash to some extent, but to judge the success of a helmet by its
    post-crash state is not the right thing to do. You want to judge
    success by the state of the head in its post-crash state!  A broken
    helmet may well have absorbed more of the energy of collision than an
    unbroken one, and so have protected the head more. I view the results
    with caution. I'm not buying a new helmet.
    
    
    Rod

Oi! So your still around then are you Rod? You don't exist on ELF, and the
Camera notesfile seems to be AWOL ...

But I digress. I've read the Which? reports too, and have followed the debate
which has ensued in the pages of Cycling Weekly. I was interested, and confused,
because I wear a Bell Quest, which is 'Recommended' by Which?, whereas other
similarly priced Bell helmets have been condemned in the same article.

One of the points made in the Which? article is that a, what I'd call
'Sacrificial Helmet' (i.e. one which breaks up on impact), does not safeguard
against secondary collisions. The kerbstone test seems to me a good idea since
that it is a more likely injury. A bit like motor vehicle manufacturers
such as Mercedes testing for oblique collisions, the most common.

I'm concerned by Which?'s adoration for the British Standard. They have decided
not to test all BS approved helmets, since 'they must be ok'. This has never
stopped them before.

Dougie

    Hi Dougie, yes, I'm still here, but since last December "here" is
    Ferney-Voltaire.
    
    The point about a helmet which breaks on initial impact not protecting
    against secondary impact is fair. Perhaps the lycra cover on mine would
    hold it together - faint hope I'm sure. If I was buying a helmet this
    year instead of two years ago, I'd buy one of the foam + thinshell ones
    which I understand hold together more.
    
    
    Rod

    
    	I've never seen a smashed helmet, so if I'm waffling forgive me.
    
    	My mental picture of a helmet that's cracked, is with a crack
    exactly where the point of contact was, with the immediate surround in
    a varying degree of decay depending on deistance from the point of
    contact.
    	The secondary collision shouldn't be so serious as the first as
    most of the momentum has been lossed in the first (eg a rebound as your
    head 'bounces' on the first collision). Although it will still need
    some form of protection, your head won't quite need the strength that
    the first, more serious one needs. You should still get 'some'
    protection (although not 100%) since part of the helmet remains in one
    piece.
    	I would prefer a helmet that stood up to th efirst collision as
    well as it does to the second, but I feel too much is being made about
    this collapse of the helmet.
    
    Graham.
    

    Uggg...  This is sounding like very nasty spec-man-ship.  I recall
    a similar situation with the NHTSA (US National Traffic Highway 
    Safety Administration - those same dolts who brought us the 55 mph
    speed limit - where they take nice new cars and drive them into
    a cement wall at 30mph, measuring the force loading on the 'heads'
    of the dumbies inside.  The tests are incredibly inaccurate and
    prone to inconsistant results - depending on things like height of
    the dumby, seat position and angle, etc.  I've seen results on the
    same model car - just different years (I think it was a Saab) which
    varied about 500% !!!!.  Well, I guess Saab DID change the headlights
    to halogen beams...
    
    To drop a helmet on a curb does seem like a reasonable test, but to
    do it in a controlled, consistant test environment is the only way
    to fairly compare different vendors.  Anything else resembles slander
    in my book.  I think Giro and Bell (among others) are trying to make
    VERY safe helmets but they DID use the concept of break-up as part
    of the intrinsic design.  Motorcycle helmets are built the same way.
    To me, this agency sound like it is just trying for some publicity.
    
    As for the lycra covers, they DO hold things together so that after
    the initial impact, the only thing you have to worry about is sharp
    objects - so just don't hit the curb on the second bounce.  From what
    I've seen of the new lightweight "hard shell" helmets, they won't 
    provide any more protection than the soft shell.  It's just a thin
    molded mylar (or similar) material.  Now the old Vetta tank helmet...
    that's a different animal!
    
    mark

RE secondary collision: this could be just as bad as the first if you were to
have an accident amidst auto traffic, since the second thing could be a car 
glancing off you. Of course, head impact may no longer be such a concern in 
these circumstances, what with the chances for spinal/neck injuries and crushing 
being much higher.