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Everything You Always Wanted To


  • pg 1
									Everyt hing You Always
Wanted To   Know About
Off-Road Moto  rcycle Helmets*
*But We  re Afraid To Ask
By Jimmy Lewis • Photos By Drew

     I and controversial subject or a downright dumber story
        f there were a bigger mystery, a more confrontational        turned to a recognized helmet testing establishment, ACT
                                                                     Lab in El Segundo, California, (formerly Collision and Injury
     for Dirt Rider to take on than this test, please let me know.   Dynamics, which did testing for Motorcyclist magazine in
     Off-road motorcycle helmets have come under more and            June 2005) and worked in conjunction with one of ACT’s
     more scrutiny lately with some much publicized accidents        staff engineers on a study for a Master’s Thesis in Mechani-
     involving high-profile athletes’ head injuries and even some    cal Engineering, all just to find out how we could learn more.
     deaths. Serious stuff. Complicated even further by additional   Currently there is no such thing as an off-road-specific helmet
     press containing uneducated viewpoints and nonscientific        standard. All helmets sold in the United States must pass the
     tests based solely on safe-sounding or popular opinions. But    DOT FMVSS 218 test if they are to be used by motorcyclists.
     this was not good enough for us to rest our delicate brain      The other popular tests you should know about are the Snell
     matter on (and in). We wanted some answers. What do the         Memorial Foundation certification M2005 for some of the
     helmet tests and the st ickers that are proudly displayed (or
     required) on the helmet mean? How do those tests equate to
                                                                     helmets tested and some European safety standards like ECE
                                                                     22-05 and BSI 6658. There are standards specific to Japan
                                                                                                                                       “Tell us how you are going to hit
     the way we hit our helmets on the ground? Does the material     and Australia as well. The ECE 22-05 test is different than
     make a difference? Does the price of a helmet matter? And       most international standards in that it only requires a single    your head and we will build you
     what is your helmet really supposed to do?                      impact per location—an approach we agree makes sense and
       We didn’t just sit at our desks and squeeze the helmets, we   used in our testing.
                                                                                                                                       the perfect helmet.”
    68 | WWW.DIRTRIDER.COM                                                                                                                                                 OCTOBER 2009 | 69

                                                                                                mittee including a specific off-road helmet
                                                                                                task group of which David Thom (engineer
                                                                                                at ACT) is a member. This group has devel-
                                                                                                oped a protocol for off-road helmets in a
                                                                                                quest toward an off-road standard. With
                                                                                                further help from ACT Lab and graduate
                                                                                                student John Prunckle, we used the ASTM
    An interesting fact is that most people      lower energy levels. Sounds pretty simple,     Off-Road Protocol which included hitting
  I know (myself included) have never had        right? Not so quick. When you review           helmets into hard-packed dirt, soft sand, a
  a concussion while not wearing a helmet.       the results table, you’ll see that none of     narrow metal edge, onto a tree branch and
  Sounds like I’m making an argument             the helmets, in any impact test, exceeded      even a footpeg. There were two differ-
  against them, but you couldn’t be further      the catastrophic magic number of 300G          ent velocities into dirt and sand for each
  from the truth. The reason we get concus-      (the G-load transferred to the head is the     helmet. Both dirt surfaces were prepped
  sions while wearing our brain buckets is       measurement we used, much further ex-          to remain consistent for each test. The
  that we put them on when we do stuff that      planation would take at least one week of      helmets were hit in different locations for
  may injure us. We are hedging a bet that if    learning high-end math). This means that       each test and it took two identical helmets
  and when we have an accident, our helmet       one could say all the helmets passed all the   to complete all of the impacts. All helmets
  will be there to protect us.                   tests. However, most scientists believe that   were impacted in the same locations for
    There is a saying in the helmet design and   lower acceleration is better, so we prefer     the same hits in relation to each other. In

                                                  “We are hedging a bet thatour hel-
  testing world that goes, “Tell us how you

                                                                               if and
  are going to hit your head and we will build
  you the perfect helmet.” That is a very
  important statement to remember through
  this entire article. We just never know the     when we have an accident,

  absolute answer to how we will crash, but
  we can make some educated predictions.
    Helmet manufacturers have many theo-
                                                  met will be there to protect us.
  ries on how to build the safest helmet, or
  one that will sell. Helmet tests are varied.   to wear a helmet that provides the lowest      other words, our testing was consistent
  There becomes a delicate balance between       Gs.                                            and repeatable. We did have to lower our
  having a helmet able to manage both a            Next you must consider the ways we hit       original velocity for the footpeg after it
  routine, lower level impact and at the same    our heads into the ground. Most of the         caused some catastrophic failures on initial
  time be able to deal with the possibility      time the impacts are what would fall under     tests. Helmets can only be asked to do so
  of a catastrophic hit. The stiffer helmets,    the very minor impact range. Since there       much, even when they are protecting mere
  in both shell design and internal foam, are    are no large-scale studies for off-road        test equipment.
  typically better performing at the cata-       motorcycle helmets that we could locate         FMVSS 218 and Snell 2005 both require
  strophic levels, yet at the same time tend     to determine further data, we draw heavily     two impacts per site, but ECE 22-05 only
  to perform worse (not poorly, just not as      from our own experiences, which tend to        hits a helmet once per site. For our tests,
  well) at lower and softer hits. Conversely,    be varied (and are not very scientific). The   we did not do any double impacts, meaning
  helmets that have softer foam and shells       ASTM (American Society for Testing and         the helmets were never subjected to more
  do a better job at the lighter impacts but     Materials) Committee for sports and ath-       than one hit in any one location. Why is
  their catastrophic failure will come at        letic equipment has a headgear subcom-         that? Because we feel that a helmet is dis-


                                                                                                   way because their first priority is to meet
  posable and can only be asked to save your                                                      certification standard(s), because they
  head one time; we’ll show and explain why    because we wanted to learn something               have to—or choose to.
  later. So you should be prepared to throw    here so we needed a large sampling of               The DOT standard is the only mandatory
  away those dollars once they have saved      helmets. We knew that the top-performing          standard in the U.S. Broken down into simple
  your head one time. Money well spent.        helmets would definitely reveal their iden-       English, it includes tests for shock absorption,
    Participation in this test was voluntary   tity, and those that were not pleased with        penetration resistance and strap strength.
  and helmet brands were able to participate   the results could keep it under wraps. For        There is no test of the chin bar whatsoever.
  anonymously. That was                                 our study the Vemar VRX-7 aver-          The next, and possibly the most controversial,
                                                        aged out to be the best perform-         has been the Snell M2005 standard which
                                                        ing helmet of the ones we tested.        includes a chin bar test and higher energy (at
                                                         There were also a few manufactur-       higher speed) tests. That is largely for two
                                                         ers which chose not to participate,     reasons, the first being the higher impacts
                                                         citing concerns from legal stand-       the helmet must take and still never transmit
                                                          points, some had issues with our       a deceleration of over 300G. M2005 is in-
                                                          testing methods, and others felt       terestingly enough changing in the very near
                                                          that other companies might send        future to the M2010 standard with different
                                                           “ringer” helmets. I discussed con-    (lower) peak levels and different weights for
                                                           cerns with each company point-        various sized headforms, bringing it more in
                                                            ing out that there was no time       line with current ECE 22-05 protocol and
                                                             to send in specially constructed    making it possible for Snell helmets also to
                                                             helmets and that our test was       pass ECE tests, something that is a bit of a
                                                              consistent and repeatable.         problem with the M2005 standard helmets.
                                                              While every impact surface and     The second issue, and something that we
                                                               velocity was released along       have concern over, is the need for a double
                                                               with the invitation to send       impact test on a single location, particularly
                                                                helmets, specific locations of   a severe impact. It is a very hard test to
                                                                the hits were never revealed.    pass, and the likelihood of an off-road helmet
                                                                Sure it was in a way random,     having to absorb a severe impact in the same
                                                                but isn’t that the nature of     location during the same crash event is very
                                                                 how a helmet must perform       slim. Remember, your helmet is a disposable
                                                                 in the real world? Or maybe     piece of safety equipment, and such a test
                                                                  helmets are built a certain    might imply that you can use your helmet

                                                                                                                            OCTOBER 2009 | 73
  after a good impact and expect it to work         available, but were all within the areas         of brain matter, and placing a G-load figure
  a second time. In the Snell Foundation’s de-      covered by the standards.                        on that is difficult. About the closest I
  fense, it claims the second impact is a way to      So what do all the numbers mean? Well,         could find to a study assigning a G value
  test helmets to a higher standard and works       the most difficult thing about under-            to a concussion was a study done for
  in place of an even more catastrophic single      standing how to protect a head is how            European football (soccer) where it said
  hit. The second hit also makes it difficult for   complicated it gets. Even the experts in         that 50 percent of the time an 80G impact
  some materials, like some lesser quality plas-    head injury and standard development             produced a concussion. The limit placed on
  tics and polycarbonates, to slip through.         don’t have all the answers yet. Differ-          most motorcycle helmets is 300G because
    What did we learn? The chart of the             entiating between a laboratory–style             it is likely levels above that could cause
  helmet impact results shows some pretty           impact (straight on, to a dead stop with         catastrophic brain injury. Further confusion
  interesting findings. First, shell material       a rebound) and a real-world impact that          is introduced since a rigid laboratory head-
  is not nearly as important as the internal        involves more of a glancing hit and some         form is not at all like a real soft and fleshy
  energy-absorbing material in most impacts.        degree of rotational accelerations is the        human head. The test headform’s job is to
  This is illustrated by the foam density sam-      first step in confusion. Our tests isolate the   isolate the performance of the helmet.
  plings versus the rankings. Most all were         vertical component. The NFL has spent mil-         For the most part, it would be simple to
  EPS (Expanded Polystyrene), and there             lions of dollars re-creating impacts in labs     say no matter what, lower Gs received by
  were some tricks and different methods            using footage shot from different angles         the head in a crash are a better thing. And
  going on inside a lot of these helmets            and examining helmets from players who           for any particular crash, this is correct.
  to absorb impacts. Many EPS liners use            were concussed. There is a difference in the     But what you are asking a helmet to do is
  multiple densities (harder = stiffer = higher     types of injuries you might sustain inside       manage energy, and technically speaking
  density), and altering the location of the        of a helmet. The most important thing you        each helmet has a finite ability to man-
  varying EPS densities makes a difference.         need to understand is that protecting the        age a certain amount of energy. The more
  Since a lot of these helmets are shooting         brain is job one, and a force the brain does     catastrophic the impact is, the more energy
  to pass a well-known and established test,        not like is the rotational force and related     that needs to be blown off, all in a very
  proper placement of foam density can be           accelerations. There is the debate between       short space and in a very short time. Dealing
  an art. But knowing that art we could have,       which is more important to protect from:         with higher and higher level impacts takes
  if we had desired, also tricked or comple-        linear acceleration and deceleration or          a stiffer energy-absorbing material(s) and a
  mented the results in choosing our strike         rotational acceleration. All humans respond      stronger shell. Both of those things typically
  points. The impact locations we chose were        differently to the sudden jerk and slowing       transmit higher Gs
  not based on the known standards we have


                                                                                               The footpeg really tests the shell of the hel-
                                                                                               met and was one of our dirt-specific tests.

  in a less severe impact. Just as a similarly   your helmet? Most of the time our crashes     conversely, someone who doesn’t wake up
  “softer” helmet would fail sooner as the       are no worse than falling straight to the     when tipping over at 10 mph give you a
  force becomes higher. It becomes an argu-      ground from a standing position, without      clue to the unpredictability of crashing and
  ment of lower Gs versus high level energy      breaking your fall, and hitting your head.    how your head reacts to impacts.
  management. And typically the standards        The force your helmet deals with has a lot      What our test did was to isolate the
  predict how a helmet will perform.             to do with the deflection of the helmet.      vertical head impact to draw comparisons
    So how hard do you hit your head when        It has a lot to do with other parts of your   between different helmets. It was also
  you crash at 20 mph, or when crashing          body hitting the ground first and helping     done to see if there were variances in the
  over a jump? Or when you tumble in the         to break the fall. That is why some of the    way different surfaces acted on the hel-
  desert at 50 mph? Or when you smack a          crazy accidents you hear about are that       mets, and how different helmets compared
  tree in the forest? What happens when you      way. Crazy. Stories like walking away from    to each other. It attempted to eliminate
  go down in the first turn and a footpeg hits   the 60-mph get-off or,                        complications so we could make compari-
                                                                                                sons between helmet A and B.
                                                                                                  At the end of all of this, there are a few
                                                                                                things that we know for sure. First, and
                                                                                                most important, is that your helmet is a
                                                                                                disposable piece of safety equipment that
                                                                                                 must be replaced after you use it. A mild
                                                                                                 crash can compress the foam even if the
                                                                                                 shell and the internal surface of the EPS
                                                                                                 look fine, and if you were to hit it in the
                                                                                                 same or similar location again, it may not
                                                                                                  do its job. Next is fit; you must have a
                                                                                                  properly (and uniformly) snug fit so that
                                                                                                  the helmet stays on your head, in position,
                                                                                                  in the event of a crash and it should be
                                                                                                  tight so that the head can’t bounce inside
                                                                                                   during a violent hit. Some speculate that
                                                                                                   up to 80 percent of riders wear a helmet
                                                                                                   that is a size too big.
                                                                                                      One more consideration you must make
                                                                                                   is price. These tests show us the price of
                                                                                                    a helmet has nothing to do with how well
                                                                                                    it will protect your head (that graphics
                                                                                                    package absorbs zero Gs), but often you
                                                                                                     can be paying for better materials, better

                                                                                                                                OCTOBER 2009 | 77

                         a step in the right direction.

                         least for those companies that

                         publish the result if it chooses.

                         since the overwhelming major-
                         of some that a mild concussion
                         is a fine trade for protection at

                         ity of mild concussions you will
                         publishes the results of random

                         test, to see if it is needed and if
                         rence crash hit. It is the opinion
                         be ready to draw a hypothetical

                         is important to us in the form of
                         we decide to wear one, we must
                         sample testing it does each year

                         helmet to manage higher energy

                         there is strong pressure to study
                           Our chart is a starting point (at

                         levels, it must become, in a lot of
                         as well but they are typically not
                         comply/fmvss218/, and you can

                         them heal before you do it again!
                           In designing a helmet and when
                         chose to reveal) to see how some

                         standards already in place. Hope-
                         helmets that still perform well on

                         it truly will differentiate from the
                         additional standards. No matter how

                         for the same thing: safer helmets.
                         force lies. Because as we expect a
                         helmets performed comparatively.

                         But there is also a strong push for
                         have this identical test performed,

                         higher levels if you ever need that,
                         The Department of Transportation

                         to any helmet company that it can
                         search out some other tests online

                         line in the sand and settle on what

                         of improving materials, production
                         at its cost, at ACT Lab and we will

                         work as well in an everyday occur-
                         at the following link: http://www.

                         catastrophic brain injuries. In total

                         the need for a dirt-oriented helmet
                         for off-highway helmets. So you do

                         techniques and soon to be released
                         fully heal from. Especially if you let
                         meet. And if you don’t see a helmet
                         much you pay, just wearing a helmet is

                         ways, stiffer and therefore may not
                         leave a lot to trust in the standards

                         concepts and designs that all strive
                         all benefit from. And there are a lot
                         fully the experts will come together
                         the smaller impacts as well as more
                         on our list, we have a standing offer
                         the helmet manufacturers choose to
                         fit and finish and for the helmet passing

                         protection and where a catastrophic

                         and agree on something that we can
                                     STanDaRDS (MeT)    SheLL MaTeRiaL OveRview   SheLL MaTeRiaL On LaBeL                                    DiRT #1       DiRT #2       DiRT facePLanT, SanD #1        SanD #2        PaveMenT         fOOTPeg          eDge               LOg
                                                                                                                                             (LefT, 5 M/S) (LefT, 8 M/S) (5 M/S)         (RighT, 5 M/S) (RighT, 8 M/S) (fT LefT, 5 M/S) (RT ReaR, 6 M/S) (RT ReaR, 7.5 M/S) (LefT ReaR, 5 M/S)
                         iD   weighT DOT ece      SneLL TheRMO- cOMPOSiTe         ABS   TheRMO- POLycaR- aRaMiD fiBeR- KevLaR caRBOn POLy    RanK acc. (g) RanK acc. (g) RanK acc. (g) RanK acc. (g) RanK acc. (g) RanK acc. (g) RanK acc. (g) RanK acc. (g)                RanK acc. (g)      MSRP
                              (gRaMS)    22-05    M2005 PLaSTic                         PLaSTic BOnaTe          gLaSS                aLLOy

                         A    1470   X                  X                               X                                                    3     138         9    258         6    100          26   134          21   173         11   124          9    107          13   182           6    121           $113.95
                         B    1355   X            X               X                                         X   X                            11    158         11   267         13   116          23   122          11   155         24   150          12   111          2    152           2    115           $329
                         c    1393   X                  X                         X     X          X                                         1     125         6    250         3    92           13   95           5    145         2    107          15   115          19   190           4    117           hJc cS-MX $89.99
                         D    1162   X    X                       X                                             X                            12    162         10   259         23   134          25   133          26   195         12   125          5    101          10   178           7    123           KaLi aaTMa $299.99
                         e    1238   X    X                       X                                             X                            21    175         15   271         6    100          17   101          22   175         1    99           6    102          5    160           13   137           $399.95
                         f    1451   X    X                       X                                             X                            7     150         1    226         2    90           24   123          15   159         2    107          3    96           1    151           5    120           $349.95
                         g    1305   X    X             X                         X                                                          21    175         22   288         6    100          21   115          25   185         7    121          11   109          4    158           3    116           $109.99
                         H    1309   X            X               X                                             X                            23    176         5    249         10   104          19   104          20   172         7    121          18   125          17   187           17   156           $324.99
                         i    1462   X            X               X                                             X      X      X              15    165         20   278         19   124          4    79           23   178         25   151          17   122          14   184           24   166           $375.99
                         J    1255   X                  X                               X                                                    9     157         6    250         16   122          9    91           16   160         15   129          14   114          11   179           10   128           $59.99
                         K    1483   X            X     X                         X     X          X                                         14    164         4    248         11   106          22   120          10   153         22   147          13   113          15   185           11   131           hJc SPX $179.99
                         L    1535   X            X               X                                             X                            13    163         14   269         12   107          11   93           19   166         18   136          26   149          17   187           21   160           $419.99
                         M    1268   X    X                       X                                             X                            18    167         16   272         18   123          5    85           4    144         10   123          1    89           6    163           8    125           veMaR vRX-5 $200
                         N    1330   X    X                       X                                             X                            2     133         3    240         6    100          16   100          12   156         6    116          2    93           3    153           1    104           veMaR vXR-7 $400
                         O    1438   X            X               X                                         X   X             X              4     143         2    236         4    93           10   92           14   158         4    114          22   128          11   179           20   157           TLD Se2 $495
                         P    1404   X            X               X                                         X   X             X              9     157         13   268         1    86           18   102          7    150         9    122          25   147          25   214           17   156           TLD Se $365
                         Q    1434   X            X     X                                          X                                         25    192         23   291         24   136          15   98           13   157         23   148          19   125          23   205           24   166           $139.95
                         R    1455   X            X     X                                          X                                         24    184         26   295         15   120          6    86           17   161         19   137          23   129          24   210           12   135           $169
                         S    1438   X            X               X                                         X   X                            26    192         23   291         14   117          14   97           24   180         21   140          7    106          7    168           21   160           $279
                         T    1288   X                  X                                                                            X       18    167         18   274         21   129          3    78           3    143         16   131          10   108          8    169           15   148           afX fX35 $90
                         U    1299   X                  X                                                                            X       5     146         19   276         21   129          7    89           1    126         4    114          4    100          9    173           9    127           afX fX86R $60
                         v    1411   X            X     X                                                                            X       8     153         8    252         5    94           1    76           2    138         13   128          7    106          15   185           14   141           afX fX18 $115
                         w    1280   X            X               X                                             X      X      X              16    166         21   280         16   122          8    90           7    150         19   137          16   117          20   195           17   156           $419.99
                         X    1525   X            X               X                                             X                            16    166         25   293         26   143          20   108          18   162         26   162          24   144          26   236           26   176           $119.99
                         y    1396   X            X               X                                             X                            6     148         11   267         20   125          2    77           6    148         13   128          20   127          21   201           23   163           $179.95
                         Z    1387   X            X     X                                X         X                                         20    174         16   272         25   140          11   93           9    151         17   135          20   127          21   201           16   154           129.95
                                                                                                                                     Min.                125              226               86                76               126               99                89                151                104
                                                                                                                                     MaX.                192              295              143               134               195              162               149                236                176
                                                                                                                                     avg.            161.4            266.2               113.5              99.3          159.2               128.9             115.8              182.5              140.7

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