Cycling is a leading cause of sport-related head injuries in the U.S. Although bicycle helmets must comply with standards limiting head acceleration in severe impacts, helmets are not evaluated under more common, concussive-level impacts, and limited data are available indicating which helmets offer superior protection. Further, standards evaluate normal impacts, while real-world cyclist head impacts are oblique—involving normal and tangential velocities. The objective of this study was to investigate differences in protective capabilities of ten helmet models under common real-world accident conditions. Oblique impacts were evaluated through drop tests onto an angled anvil at common cyclist head impact velocities and locations. Linear and rotational accelerations were evaluated and related to concussion risk, which was then correlated with design parameters. Significant differences were observed in linear and rotational accelerations between models, producing concussion risks spanning >50% within single impact configurations. Risk differences were more attributable to linear acceleration, as rotational varied less between models. At the temporal location, shell thickness, vent configuration, and radius of curvature were found to influence helmet effective stiffness. This should be optimized to reduce impact kinematics. At the frontal, helmet rim location, liner thickness tapered off for some helmets, likely due to lack of standards testing at this location. This is a frequently impacted location for cyclists, suggesting that the standards testable area should be expanded to include the rim. These results can inform manufacturers, standards bodies, and consumers alike, aiding the development of improved bicycle helmet safety.

References

References
1.
AANS
,
2014
, “
Sports-Related Head Injury
,” American Association of Neurological Surgeons, Rolling Meadows, IL, accessed Apr. 28, 2018, http://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Sports-related-Head-Injury
2.
CPSC
,
2015
, “
National Electronic Injury Surveillance System Database
,” United States Consumer Product Safety Commission, Rockville, MD, accessed Apr. 28, 2018, www.cpsc.gov/en/Research–Statistics/NEISS-Injury-Data/
3.
Schulman
,
J.
,
Sacks
,
J.
, and
Provenzano
,
G.
,
2002
, “
State Level Estimates of the Incidence and Economic Burden of Head Injuries Stemming From Non-Universal Use of Bicycle Helmets
,”
Injury Prev.
,
8
(
1
), pp.
47
52
.
4.
Sacks
,
J. J.
,
Holmgreen
,
P.
,
Smith
,
S. M.
, and
Sosin
,
D. M.
,
1991
, “
Bicycle-Associated Head Injuries and Deaths in the United States From 1984 Through 1988: How Many are Preventable?
,”
J. Am. Med. Assoc.
,
266
(
21
), pp.
3016
3018
.
5.
Thompson
,
D. C.
,
Rivara
,
F. P.
, and
Thompson
,
R. S.
,
1996
, “
Effectiveness of Bicycle Safety Helmets in Preventing Head Injuries. A Case-Control Study
,”
J. Am. Med. Assoc.
,
276
(
24
), pp.
1968
1973
.
6.
Elvik
,
R.
,
2013
, “
Corrigendum to: ‘Publication Bias and Time-Trend Bias in Meta-Analysis of Bicycle Helmet Efficacy: A Re-Analysis of Attewell, Glase and McFadden, 2001’ [Accid. Anal. Prev. 43 (2011) 1245-1251]
,”
Accid. Anal. Prev.
,
60
, pp.
245
253
.
7.
Amoros
,
E.
,
Chiron
,
M.
,
Martin
,
J. L.
,
Thelot
,
B.
, and
Laumon
,
B.
,
2012
, “
Bicycle Helmet Wearing and the Risk of Head, Face, and Neck Injury: A French Case–Control Study Based on a Road Trauma Registry
,”
Inj. Prev.
,
18
(
1
), pp.
27
32
.
8.
Cripton
,
P. A.
,
Dressler
,
D. M.
,
Stuart
,
C. A.
,
Dennison
,
C. R.
, and
Richards
,
D.
,
2014
, “
Bicycle Helmets are Highly Effective at Preventing Head Injury During Head Impact: Head-Form Accelerations and Injury Criteria for Helmeted and Unhelmeted Impacts
,”
Accid. Anal. Prev.
,
70
, pp.
1
7
.
9.
McIntosh
,
A. S.
,
Lai
,
A.
, and
Schilter
,
E.
,
2013
, “
Bicycle Helmets: Head Impact Dynamics in Helmeted and Unhelmeted Oblique Impact Tests
,”
Traffic Inj. Prev.
,
14
(
5
), pp.
501
508
.
10.
CPSC
,
1998
, “
Safety Standard for Bicycle Helmets Final Rule (16 CFR Part 1203)
,” United States Consumer Product Safety Commission, Rockville, MD, pp.
11711
11747
.
11.
Mertz
,
H. J.
,
Irwin
,
A. L.
, and
Prasad
,
P.
,
2003
, “
Biomechanical and Scaling Bases for Frontal and Side Impact Injury Assessment Reference Values
,”
Stapp Car Crash J.
,
47
, pp.
155
188
.https://www.sae.org/publications/technical-papers/content/2003-22-0009/
12.
Smith
,
T. A.
,
Tees
,
D.
,
Thom
,
D. R.
, and
Hurt
,
H. H.
,
1994
, “
Evaluation and Replication of Impact Damage to Bicycle Helmets
,”
Accid. Anal. Prev.
,
26
(
6
), pp.
795
802
.
13.
Williams
,
M.
,
1991
, “
The Protective Performance of Bicyclists' Helmets in Accidents
,”
Accid. Anal. Prev.
,
23
(
2–3
), pp.
119
131
.
14.
Pellman
,
E. J.
,
Viano
,
D. C.
,
Tucker
,
A. M.
,
Casson
,
I. R.
, and
Waeckerle
,
J. F.
,
2003
, “
Concussion in Professional Football: Reconstruction of Game Impacts and Injuries
,”
Neurosurgery
,
53
(
4
), pp.
799
812
.
15.
Rowson
,
S.
, and
Duma
,
S. M.
,
2013
, “
Brain Injury Prediction: Assessing the Combined Probability of Concussion Using Linear and Rotational Head Acceleration
,”
Ann. Biomed. Eng.
,
41
(
5
), pp.
873
882
.
16.
Bourdet
,
N.
,
Deck
,
C.
,
Carreira
,
R. P.
, and
Willinger
,
R.
,
2012
, “
Head Impact Conditions in the Case of Cyclist Falls
,”
Proc. Inst. Mech. Eng., Part P: J. Sports Eng. Technol.
,
226
(
3–4
), pp.
282
289
.
17.
Ching
,
R. P.
,
Thompson
,
D. C.
,
Thompson
,
R. S.
,
Thomas
,
D. J.
,
Chilcott
,
W. C.
, and
Rivara
,
F. P.
,
1997
, “
Damage to Bicycle Helmets Involved With Crashes
,”
Accid. Anal. Prev.
,
29
(
5
), pp.
555
562
.
18.
McIntosh
,
A.
,
Dowdell
,
B.
, and
Svensson
,
N.
,
1998
, “
Pedal Cycle Helmet Effectiveness: A Field Study of Pedal Cycle Accidents
,”
Accid. Anal. Prev.
,
30
(
2
), pp.
161
168
.
19.
Depreitere
,
B.
,
Van Lierde
,
C.
,
Maene
,
S.
,
Plets
,
C.
,
Vander Sloten
,
J.
,
Van Audekercke
,
R.
,
Van der Perre
,
G.
, and
Goffin
,
J.
,
2004
, “
Bicycle-Related Head Injury: A Study of 86 Cases
,”
Accid. Anal. Prev.
,
36
(
4
), pp.
561
567
.
20.
Bourdet
,
N.
,
Deck
,
C.
,
Serre
,
T.
,
Perrin
,
C.
,
Llari
,
M.
, and
Willinger
,
R.
,
2014
, “
In-Depth Real-World Bicycle Accident Reconstructions
,”
Int. J. Crashworthiness
,
19
(
3
), pp.
222
232
.
21.
Verschueren
,
P.
,
2009
, “
Biomechanical Analysis of Head Injuries Related to Bicycle Accidents and a New Bicycle Helmet Concept
,” Ph.D. thesis, Katholieke Universiteit, Leuven, Belgium.
22.
Fahlstedt
,
M.
,
Baeck
,
K.
,
Halldin
,
P.
,
Vander Sloten
,
J.
,
Goffin
,
J.
,
Depreitere
,
B.
, and
Kleiven
,
S.
,
2012
, “
Influence of Impact Velocity and Angle in a Detailed Reconstruction of a Bicycle Accident
,” International Research Council on the Biomechanics of Injury Conference (
IRCOBI
), Dublin, Ireland, Sept. 12–14, pp.
787
799
.https://www.researchgate.net/publication/286062096_Influence_of_impact_velocity_and_angle_in_a_detailed_reconstruction_of_a_bicycle_accident
23.
Peng
,
Y.
,
Chen
,
Y.
,
Yang
,
J.
,
Otte
,
D.
, and
Willinger
,
R.
,
2012
, “
A Study of Pedestrian and Bicyclist Exposure to Head Injury in Passenger Car Collisions Based on Accident Data and Simulations
,”
Saf. Sci.
,
50
(
9
), pp.
1749
1759
.
24.
Otte
,
D.
,
1989
, “
Injury Mechanism and Crash Kinematics of Cyclists in Accidents—An Analysis of Real Accidents
,”
SAE
Paper No. 892425.
25.
Milne
,
G.
,
Deck
,
C.
,
Bourdet
,
N.
,
Carreira
,
R. P.
,
Allinne
,
Q.
,
Gallego
,
A.
, and
Willinger
,
R.
,
2014
, “
Bicycle Helmet Modelling and Validation Under Linear and Tangential Impacts
,”
Int. J. Crashworthiness
,
19
(
4
), pp.
323
333
.
26.
Aare
,
M.
, and
Halldin
,
P.
,
2003
, “
A New Laboratory Rig for Evaluating Helmets Subject to Oblique Impacts
,”
Traffic Inj. Prev.
,
4
(
3
), pp.
240
248
.
27.
King
,
A. I.
,
Yang
,
K. H.
,
Zhang
,
L.
,
Hardy
,
W.
, and
Viano
,
D. C.
,
2003
, “
Is Head Injury Caused by Linear or Angular Acceleration?
,”
International Research Conference on the Biomechanics of Impact
(
IRCOBI
), Lisbon, Portugal, Sept. 25–26, pp. 1–12.http://snellfoundation.net/docs/articles/hic/King_IRCOBI_2003.pdf
28.
Unterharnscheidt
,
F. J.
,
1971
, “
Translational Versus Rotational Acceleration—Animal Experiments With Measured Inputs
,”
SAE
Paper No. 710880.
29.
Gennarelli
,
T.
,
Ommaya
,
A.
, and
Thibault
,
L.
,
1971
, “
Comparison of Translational and Rotational Head Motions in Experimental Cerebral Concussion
,”
15th Stapp Car Crash Conference
, Coronado, CA, Nov. 17–19, pp.
797
803
.
30.
Gennarelli
,
T. A.
,
Thibault
,
L. E.
, and
Ommaya
,
A. K.
,
1972
, “
Pathophysiologic Responses to Rotational and Translational Accelerations of the Head
,”
SAE
Paper No. 720970.
31.
Ommaya
,
A.
, and
Hirsch
,
A.
,
1971
, “
Tolerances for Cerebral Concussion From Head Impact and Whiplash in Primates
,”
J. Biomech.
,
4
(
1
), pp.
13
21
.
32.
Ommaya
,
A. K.
,
Hirsch
,
A. E.
, and
Martinez
,
J. L.
,
1966
, “
The Role of Whiplash in Cerebral Concussion
,”
Tenth Stapp Car Crash Conference
, Los Angeles, CA, Nov. 8–9, pp.
314
324
.
33.
Rowson
,
S.
,
Brolinson
,
G.
,
Goforth
,
M.
,
Dietter
,
D.
, and
Duma
,
S. M.
,
2009
, “
Linear and Angular Head Acceleration Measurements in Collegiate Football
,”
ASME J. Biomech. Eng.
,
131
(
6
), p.
061016
.
34.
Mills
,
N. J.
, and
Gilchrist
,
A.
,
2008
, “
Oblique Impact Testing of Bicycle Helmets
,”
Int. J. Impact Eng.
,
35
(
9
), pp.
1075
1086
.
35.
Halldin
,
P.
, and
Kleiven
,
S.
,
2013
, “
The Development of Next Generation Test Standards for Helmets
,”
Helmet Performance and Design
,
P.
Childs
,
A.
Bull
, and
M.
Ghajari
, eds.,
DEG Imperial College
,
London
.
36.
Klug
,
C.
,
Feist
,
F.
, and
Tomasch
,
E.
,
2015
, “
Testing of Bicycle Helmets for Preadolescents
,”
International Research Council on the Biomechanics of Injury Conference (IRCOBI Conference)
, Lyon, France, Sept. 9–11, Paper No.
IRC-15-24
http://www.ircobi.org/wordpress/downloads/irc15/pdf_files/24.pdf.
37.
Hansen
,
K.
,
Dau
,
N.
,
Feist
,
F.
,
Deck
,
C.
,
Willinger
,
R.
,
Madey
,
S. M.
, and
Bottlang
,
M.
,
2013
, “
Angular Impact Mitigation System for Bicycle Helmets to Reduce Head Acceleration and Risk of Traumatic Brain Injury
,”
Accid. Anal. Prev.
,
59
, pp.
109
117
.
38.
Stigson, H.
,
Rizzi, M.
,
Ydenius, A.
,
Engstroem, E.
, and
Kullgren, A.
, 2017, “
Consumer Testing of Bicycle Helmets
,” International Research Council on the Biomechanics of Injury Conference (IRCOBI Conference), Antwerp, Belgium, Sept. 13–15, Paper No.
IRC-17-30
.http://www.ircobi.org/wordpress/downloads/irc17/pdf-files/30.pdf
39.
Nightingale
,
R. W.
,
McElhaney
,
J. H.
,
Richardson
,
W. J.
, and
Myers
,
B. S.
,
1996
, “
Dynamic Responses of the Head and Cervical Spine to Axial Impact Loading
,”
J. Biomech.
,
29
(
3
), pp.
307
318
.
40.
Rowson
,
B.
,
Rowson
,
S.
, and
Duma
,
S. M.
,
2015
, “
Hockey STAR: A Methodology for Assessing the Biomechanical Performance of Hockey Helmets
,”
Ann. Biomed. Eng.
,
43
(
10
), pp.
2429
2443
.
41.
Cobb
,
B. R.
,
Zadnik
,
A. M.
, and
Rowson
,
S.
,
2015
, “
Comparative Analysis of Helmeted Impact Response of Hybrid III and National Operating Committee on Standards for Athletic Equipment Headforms
,”
Proc. Inst. Mech. Eng., Part P: J. Sports Eng. Technol.
,
230
(
1
), pp.
50
60
.
42.
Hering
,
A. M.
, and
Derler
,
S.
,
2000
, “
Motorcycle Helmet Drop Tests Using a Hybrid III Dummy
,”
The International IRCOBI Conference on the Biomechanics of Impact
, Montpellier, France, Sept. 20–22, pp. 307–321.
43.
ECE
,
1999
, “
Uniform Provisions Concerning the Approval of Protective Helmets and Their Visors for Drivers and Passengers of Motorcycles and Mopeds
,” United Nations Economic Commission for Europe, Geneva, Switzerland, Standard No.
R-22.05
.https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/r022r4e.pdf
44.
Cobb
,
B. R.
,
Tyson
,
A. M.
, and
Rowson
,
S.
,
2017
, “
Head Acceleration Measurement Techniques: Reliability of Angular Rate Sensor Data in Helmeted Impact Testing
,”
Proc. Inst. Mech. Eng., Part P: J. Sports Eng. Technol.
, epub.
45.
Langburt
,
W.
,
Cohen
,
B.
,
Akhthar
,
N.
,
O'Neill
,
K.
, and
Lee
,
J. C.
,
2001
, “
Incidence of Concussion in High School Football Players of Ohio and Pennsylvania
,”
J. Child Neurol.
,
16
(
2
), pp.
83
85
.
46.
McCrea
,
M.
,
Hammeke
,
T.
,
Olsen
,
G.
,
Leo
,
P.
, and
Guskiewicz
,
K.
,
2004
, “
Unreported Concussion in High School Football Players: Implications for Prevention
,”
Clin. J. Sport Med.
,
14
(
1
), pp.
13
17
.
47.
Mills
,
N. J.
,
1990
, “
Protective Capability of Bicycle Helmets
,”
Br. J. Sports Med.
,
24
(
1
), pp.
55
60
.
48.
Mills
,
N. J.
, and
Gilchrist
,
A.
,
1996
, “
Response of Helmets in Direct and Oblique Impacts
,”
Int. J. Crashworthiness
,
2
(
1
), pp.
7
24
.
49.
Mills
,
N. J.
, and
Gilchrist
,
A.
,
2008
, “
Finite-Element Analysis of Bicycle Helmet Oblique Impacts
,”
Int. J. Impact Eng.
,
25
(
9
), pp.
1087
1101
.
50.
Bland
,
M. L.
,
Zuby
,
D. S.
,
Mueller
,
B. C.
, and
Rowson
,
S.
,
2018
, “
Differences in the Protective Capabilities of Bicycle Helmets in Real-World and Standard-Specified Impact Scenarios
,”
Traffic Inj. Prev.
,
19
(Suppl. 1), pp. S158–S163.
51.
Newman
,
J. A.
,
Shewchenko
,
N.
, and
Welbourne
,
E.
,
2000
, “
A Proposed New Biomechanical Head Injury Assessment Function—the Maximum Power Index
,”
Stapp Car Crash J.
,
44
, pp.
215
247
.https://pdfs.semanticscholar.org/4697/a698a53ee84563b00e764d9af8b1d9fb64ea.pdf
52.
Rowson
,
S.
,
Duma
,
S. M.
,
Beckwith
,
J. G.
,
Chu
,
J. J.
,
Greenwald
,
R. M.
,
Crisco
,
J. J.
,
Brolinson
,
P. G.
,
Duhaime
,
A. C.
,
McAllister
,
T. W.
, and
Maerlender
,
A. C.
,
2012
, “
Rotational Head Kinematics in Football Impacts: An Injury Risk Function for Concussion
,”
Ann. Biomed. Eng.
,
40
(
1
), pp.
1
13
.
53.
Rowson
,
S.
,
Beckwith
,
J. G.
,
Chu
,
J. J.
,
Leonard
,
D. S.
,
Greenwald
,
R. M.
, and
Duma
,
S. M.
,
2011
, “
A Six Degree of Freedom Head Acceleration Measurement Device for Use in Football
,”
J. Appl. Biomech.
,
27
(
1
), pp.
8
14
.
54.
Laituri
,
T. R.
,
El-Jawahri
,
R. E.
,
Henry
,
S.
, and
Sullivan
,
K.
,
2015
, “
Field-Based Assessments of Various AIS2+ Head Risk Curves for Frontal Impact
,”
SAE
Paper No. 2015-01-1437.
55.
Cobb
,
B. R.
,
MacAlister
,
A.
,
Young
,
T. J.
,
Kemper
,
A. R.
,
Rowson
,
S.
, and
Duma
,
S. M.
,
2014
, “
Quantitative Comparison of Hybrid III and National Operating Committee on Standards for Athletic Equipment Headform Shape Characteristics and Implications on Football Helmet Fit
,”
Proc. Inst. Mech. Eng., Part P: J. Sports Eng. Technol.
,
229
(
1
), pp.
39
46
.
56.
Sances
,
A.
,
Carlin
,
F.
, and
Kumaresan
,
S.
,
2002
, “
Biomechanical Analysis of Head-Neck Force in Hybrid III Dummy During Inverted Vertical Drops
,”
Biomed. Sci. Instrum.
,
38
, pp.
459
464
.
57.
Ghajari
,
M.
,
Peldschus
,
S.
,
Galvanetto
,
U.
, and
Iannucci
,
L.
,
2013
, “
Effects of the Presence of the Body in Helmet Oblique Impacts
,”
Accid. Anal. Prev.
,
50
, pp.
263
271
.
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