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Original Article
Proc IMechE Part P:J Sports Engineering and Technology2019, Vol.
233(2) 268–276� IMechE 2019Article reuse
guidelines:sagepub.com/journals-permissionsDOI:
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Aerodynamic test results of bicyclehelmets in different
configurations:Towards a responsive design
James Novak1 , David Burton2 and Timothy Crouch2
AbstractWithin the sport of cycling, aerodynamic efficiency is a
fundamental criterion for equipment such as bicycle frames,wheels,
clothing and helmets. Emerging technologies continually challenge
the rules governing the sport as designers,engineers, sports
scientists and athletes attempt to gain the edge on their
competition. This study compares three-dimensional (3D) printed
bicycle helmet prototypes with three commercially available helmets
via aerodynamic testing ina wind tunnel. One 3D printed helmet
featured a mechanical mechanism allowing two states of ventilation
closure to beexamined for aerodynamic efficiency, while the other
featured electronically adjustable ventilation openings tested at
fivedifferent states of ventilation closure. Data were collected
using an anthropometrically accurate mannequin sitting atop
abicycle in a road-cycling position. The results found that the
mechanically controlled prototype offered a 4.1% increasein overall
drag experienced by the mannequin with ventilation in the open
position compared to the closed position.The electronic prototype
showed an increase in drag as ventilation openings increased
through the five states, with anoverall difference in drag of 3.7%
between closed and the maximum opening. These experimental findings
indicate thatthe responsive helmet prototypes can significantly
affect the drag force on a cyclist between their closed and open
posi-tions and, when understood as being adaptable using sensors
and automated controls, may provide new opportunitiesto modify
athlete performance throughout varying stages of training and
competition.
Keywords3D printing, four-dimensional (4D) product, cycling,
sports technology, ubiquitous computing, wearable technology,
windtunnel
Date received: 18 February 2018; accepted: 11 December 2018
Introduction
The modern sports industry is heavily influenced bytechnology,1
with cycling having been described by19th century French author
Louis Baudry de Saunieras a sport where man is ‘‘half made of flesh
and half ofsteel that only our century of science and iron
couldhave spawned.’’2 It is no wonder then that numerousstudies
have investigated the aerodynamic properties ofbicycle helmets,
being one of the required protectivedevices worn in competition
under Union CyclisteInternationale (UCI) regulations and mandatory
forrecreation in several countries. Studies have found thatthe
helmet alone is responsible for 2%–8% of the totalaerodynamic drag
on a cyclist at speeds of 30 km/h orgreater.3,4 More specific
studies into the design featuresof specialty time-trial helmets
have shown that helmetaerodynamic efficiency can be improved when
time-trial helmets are designed with a long length andsmooth
vents.5 ‘‘Therefore, an aerodynamically
efficient helmet can provide a competitive advantageand by
selecting appropriate helmets and maintainingcorrect body position,
a cyclist can reduce aerodynamicdrag notably and the conserved
energy can be used atappropriate stages of racing.’’5
A previous study by Alam et al.6 experimented withcovering air
vents of a Giro Atmos helmet to comparethe aerodynamic and thermal
changes in a wind tunnel.The results showed a 12% reduction in the
drag
1Product Design, School of Design, Architecture and Building,
University
of Technology Sydney, Ultimo, NSW, Australia2Mechanical and
Aerospace Engineering, Monash University, Melbourne,
VIC, Australia
Corresponding author:
James Novak, Product Design, School of Design, Architecture
and
Building, University of Technology Sydney, 15 Broadway, Ultimo,
NSW
2007, Australia.
Email: [email protected]
https://uk.sagepub.com/en-gb/journals-permissionshttps://doi.org/10.1177/1754337118822613journals.sagepub.com/home/piphttp://crossmark.crossref.org/dialog/?doi=10.1177%2F1754337118822613&domain=pdf&date_stamp=2019-01-12
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coefficient for the modified helmet compared to thestandard
helmet. However, when air vents were cov-ered, thermal performance
was compromised with anincrease of 1.2 �C at a speed of 30 km/h,
meaning lesscooling effect for the cyclist. This study highlighted
thesignificance that air vent location, size and quantitycan have
on the performance of a cyclist, importantconsiderations cyclists
need to make when selecting ahelmet for competition or leisure.
A number of new bicycle helmets have emerged inrecent years that
give cyclists the opportunity to controlthis balance between
aerodynamics and thermal regula-tion. One example is the Infinity
helmet (Kask,Chiuduno, BG, Italy), which includes an
adjustableventilation piece, whereby the cyclist can manuallyopen
or close the primary ventilation holes to suit theirneeds. For
example, the vents can be opened whenclimbing uphill to maximize
cooling or closed whensprinting to minimize drag. Similarly, the
Star Pro hel-met (Bell Sports, Rantoul, IL, USA) allows riders
tomanually control covers for the ventilation holes with aslider
button. While the study by Alam et al.6 wouldindicate the benefits
of such adaptability, peer-revieweddata have not been published
about the efficiency ofthese commercial designs. Furthermore, the
manualprocess of modifying ventilation in these designs is sub-ject
to human error (i.e. a cyclist may forget to open orclose the
vents, thereby experiencing increased aerody-namic drag or a
reduced cooling effect). Furthermore,the adjustment of the vents
requires the cyclist toremove their hand from the handlebar,
sacrificingbicycle control for a short time.
To improve the practical implementation of adjusta-ble vent
designs, prototype helmets featuring electro-mechanical systems
have been developed for this pilotstudy, leveraging ubiquitous
computing principles (thewidespread embedding of computational
power andsensors into everyday objects).7 More specifically,
theprototypes used in this study are examples of four-dimensional
(4D) products,8 an emerging field of prod-uct development which
provides the ‘‘ability for theproduct to physically evolve over
time to suit changesin user needs,’’8 without direct input or
control by theuser. Such products may also be described as
beingresponsive.
The primary aim of this study was to gather empiri-cal data
regarding the aerodynamic drag properties ofthe three-dimensional
(3D) printed prototype helmetswith variable ventilation, comparing
them to existingcommercially available helmets in a number of
config-urations. Unlike previous studies, prototype helmetswere
specifically designed and 3D printed to explorevariable
ventilation, rather than simply taping overvents on existing
designs. The secondary aim of thisstudy was to extrapolate results
into an understandingof how a responsive helmet may affect a
cyclist duringtraining or competition, allowing for further
researchdirections beyond the scope of this study.
Experimental procedure
Description of helmets
This study used three commercially available bicyclehelmets and
three 3D printed prototype helmets asshown in Figure 1. The S-Works
Evade (SpecializedBicycle Components, Morgan Hill, CA, USA)
wasselected as the baseline helmet for comparison, sinceit is a
commonly available helmet widely used byrecreational and
professional cyclists for its aerody-namic and thermal properties.
The Bambino (Kask,Chiuduno, BG, Italy) and Advantage (Giro,
SantaCruz, CA, USA) were selected as premium aerody-namic helmets
typically used for time-trial racing.Using these helmets allowed
the authors to gain abetter understanding about aerodynamic drag at
thespecialist end of bicycle helmet design, while alsodetermining
whether the 3D printed prototypescould achieve similar levels of
aerodynamic effi-ciency when vents were closed. The Bambino
andAdvantage were both tested with and without theirvisor
attachments, while the Advantage was alsotested with the vents
taped over with the visorattached as shown in Figure 2.
Development of prototypes
The form of Prototype 1 was created by 3D scanning abudget level
Series 1 helmet (Cyclops, Tullamarine,VIC, Australia), which meets
Australian Standards AS/NZS 2063. The standard vacuum-formed
exterior wasremoved, and a larger 3D printed shell was producedon a
standard desktop fused-deposition modeling(FDM) 3D printer in
multiple pieces and then gluedonto the foam interior. Prototype 2
is identical in sizeand shape to Prototype 1 with the same size and
loca-tion of ventilation with the only difference being
thatPrototype 2 had additional ventilation covers, whichcould be
opened and closed mechanically. For thisstudy, only the open and
closed positions were testedwith no electronic system attached to
this prototype.
Prototype 3, also known as the ‘‘Dynaero’’ helmet,8
was designed as an original piece for this research and3D
printed using selective-laser sintering (SLS) technol-ogy, which is
more robust and accurate than FDM.This helmet has a built-in micro
servo to control theopening angle of the two large vent openings,
whichhave been designed using a different method ofmechanical
movement to Prototype 2 to compare theeffect on aerodynamic
performance in these tests. Anoverview of dimensions of the three
3D printed proto-types is shown in Figure 3. A specific mobile
applica-tion was developed for android devices to control
theopening of the vents of Prototype 3 via a bluetoothconnection.
During testing, the batteries and other elec-tronics for the helmet
were placed inside the chest cav-ity of the mannequin so as not to
interfere with theaerodynamics of the model cyclist.
Novak et al. 269
-
Cycling mannequin
Some studies of the aerodynamic properties of bicyclehelmets
have used a mannequin head for testing,3 whileothers have used a
purpose-built mannequin torso withhead in a riding position.5,6
This particular study used afull-size, anthropometrically accurate
mannequin repre-sentative of an adult male time-trial cyclist,
sitting atopa carbon fiber racing bicycle in a road-riding
positionsimilar to past studies.5,6 The mannequin, fitted with
aracing skinsuit, pedaled at 80 6 1 r/min for all tests sothat the
wheel ground speed matched wind tunnel testvelocity of 44 km/h. The
position of the mannequin andthe cycling equipment worn by the
mannequin did notvary throughout testing. Cameras were fixed
aroundthe wind tunnel circuit to capture frontal and side viewsof
the mannequin. Images recorded by these cameraswere compared
between tests to determine if any move-ment in the mannequin’s
position or equipment hadoccurred between tests.
Wind tunnel facility
A three-fourth open-jet wind tunnel facility located atMonash
University was used for aerodynamic evaluationof the helmets used
in this study. All wind tunnel experi-ments were performed within
the three-fourth open-jet testsection located within the return
circuit of this wind tunnelas shown in Figure 4. Wind tunnel and
flow quality char-acteristics of the test section are shown in
Table 1.
The front and rear wheels of the fixed-gear bicycleare driven
via an electric motor that powers rollerslocated underneath them.
Due to the fixed-gear design,when the rear wheel is powered, the
mannequin’s legsare driven around the pedal stroke.
Figure 1. Front and side profiles of helmets in this study:
(a)specialized S-Works Evade, (b) Kask Bambino—tested with visoron
and off, (c) Giro Advantage—tested with visor on and off andvents
covered, (d) Prototype 1—Passive Vents, (e) Prototype2—Active
Vents—tested in open and closed positions, and (f)Protype
3—Dynaero—tested at five vent-opening settings.
Figure 2. Giro Advantage with vents taped and visor
attached.
270 Proc IMechE Part P: J Sports Engineering and Technology
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To reduce the impact of the wind tunnel floorboundary layer on
the force measurements, the manne-quin and bicycle were positioned
on top of a raisedcantilevered platform. Struts attached to either
side ofthe front and rear axles were used to rigidly fix thebicycle
to the force balance housed underneath thewind tunnel floor. No
attempt has been made to sub-tract aerodynamic forces acting on the
struts from themeasurements or correct aerodynamics forces for
open-jet blockage effects. The force balance has been devel-oped
in-house at Monash University and consists of astrain gauge and
floating table design utilizing airbearings.
A single test involved recording baseline measure-ments with no
wind before and after force measure-ments of the mannequin so that
any drift in the forcemeasurement system over the duration of a
test couldbe monitored and corrected for. Force measurementsare
taken as the mean result of three separate tests thatwere sampled
at 500 Hz for 40 s for all helmet varia-tions, except for the
S-Works Evade which was testedfive times at the start of the wind
tunnel testing, with a
sixth test completed at the conclusion of all testing toensure
wind tunnel consistency. The maximum varia-tion in time-averaged
forces for a given helmet was typi-cally \ 0.5%. All aerodynamic
drag measurements‘‘D’’ in this study are reported as drag area
measure-ments using equation (1)
CdA=D
12 rU
2‘
ð1Þ
where r and U‘ represent the test section air densityand test
velocity, respectively. The drag area is theproduct of the drag
coefficient (Cd) and a referencearea (A), which is typically taken
as the projected fron-tal area of the cyclist and bicycle. The
uncertainty asso-ciated with the mean calculated from repeated
CdAmeasurements is \ 60.001 m2.
Results
Commercially available helmet results
The average drag area measurements for the six hel-mets in this
study are shown in Figure 5. Overall theAdvantage and Bambino
helmets had the lowest aero-dynamic drag resistance when used with
the visor thanthe other helmets used in this study. The CdA of
thesetime-trial helmets was ;2% lower than the CdA of themannequin
fitted with the S-Works Evade road helmet.Others have also shown
the Giro Advantage to per-form well when the aerodynamic
performance of this
Figure 3. Overall dimensions of the three 3D printed
prototypes.
Figure 4. Monash University wind tunnel showing details of the
testing location used for this study.
Table 1. Wind tunnel and flow characteristics.
Type Three-fourth open-jet returnJet cross-sectional area 2.6 3
4.0 m2
Turbulence intensity \ 1.6%Flow uniformity \ 1%Flow angularity
61Blockage ratio \ 5%
Novak et al. 271
-
helmet is compared with other road and time-trialhelmets.5
Figure 6 compares the impact of modifications madeto the
standard baseline helmet configurations (visorremoved, vents taped)
as a percentage change in CdA.Removing the visor from both the
Advantage andBambino resulted in an increase in aerodynamic
drag.However, the aerodynamic performance of theBambino helmet was
far more sensitive to the removalof the visor, resulting in a 4.8%
increase in CdA com-pared to the 0.8% increase for the Advantage.
Theincrease in CdA for the Bambino suggests that this hel-met was
designed to only be used with the visorattached. Figure 6 also
shows that closing the vents ofthe Advantage did not have a
significant effect on itsaerodynamic performance (;0.25%). Similar
studieshave shown that closing the vents can reduce aerody-namic
drag by as much as 12% in some helmetdesigns.6 However, this was
not the case for theAdvantage helmet, which is designed for
time-trialracing, where low aerodynamic resistance is the
priority, and the location and size of ventilation is opti-mized
to cause minimal impact to aerodynamicperformance.
Prototype helmet results
Prototype 1 recorded a CdA 3.0% higher than the base-line
S-Works Evade, which is not surprising, given thatthe form of
Prototype 1 was taken from a budget hel-met design, and the S-Works
Evade is a premium hel-met designed for high performance. By
covering thevents, represented by Prototype 2 with vents closed,
thedrag area was reduced by 0.9%, which would be a sig-nificant
advantage for an athlete during competition.This result is similar
to the Alam et al.6 experimentalstudy which found improved
aerodynamic performancewith a Giro Atmos helmet when ventilation
holes weretaped closed. When comparing the closed and openvents of
Prototype 2, a 4.1% increase in CdA occurswith the vents open.
Referring to the side view of thehelmet in Figure 1(e), it is clear
that the open vents
0.210 0.215 0.220 0.225 0.230 0.235 0.240 0.245
S-Works Evade
Bambino with visor
Bambino without visor
Advantage with visor
Advantage without visor
Advantage with visor and vents taped
Prototype 1 with passive vents
Prototype 2 with vents closed
Prototype 2 with vents open
Prototype 3 with vents closed
Prototype 3 with vents open 40mm
CdA(m²)
Figure 5. The average drag area (CdA) for the six helmets with
different conditions as specified at a wind speed of 44 km/h.
0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0% 3.5% 4.0% 4.5% 5.0%
Bambino without visor
Advantage without visor
Advantage with visor and vents taped
Prototype 2 with vents open
Prototype 3 with vents open 10mm
Prototype 3 with vents open 20mm
Prototype 3 with vents open 30mm
Prototype 3 with vents open 40mm
Figure 6. Comparison of helmets in different configurations.
272 Proc IMechE Part P: J Sports Engineering and Technology
233(2)
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increased projected area exposed to the flow, acting likescoops,
resulting in higher CdA measurements. Theability to increase the
area of the vents directly exposedto wind flow outside the normal
bounds of the helmetmeans that there may be an increased ability to
coolthe head via forced convection than the traditional pas-sive
vent helmet designs. This hypothesis would formpart of a secondary
study.
While the extreme results (open and closed) for theelectronic
Prototype 3 are shown in Figure 5, moredetailed aerodynamic drag
area results of the five ventpositions tested in the wind tunnel
are shown inFigure 7. Here the vent positions are represented bythe
ratio of the projected frontal area of the ventopenings to the
total projected area of the helmet.The vent projected area is
calculated from the size ofthe vent opening which was measured in
the test sec-tion at wind tunnel test speed. Aerodynamic
loadsresulted in some movement in the vent mechanism,which was
estimated to be 62.5 mm and is the majorcontributing factor to the
uncertainty associated withthe measurement of the vented area.
Figure 8 pro-vides a visual representation of the zones deemed tobe
vent areas and non-vented areas of the helmet. Thetotal projected
area of the helmet is found by sum-ming both vented and non-vented
areas.
Figure 7 shows that as the vent area ratio increases,so too does
the aerodynamic drag area. A vent arearatio of 0.097 increased the
drag area by 0.6% than thehelmet in the closed position, while at
the maximumratio of 0.35, the drag area was 3.7% greater. This
issimilar in magnitude to the differences recorded foropen and
closed vent positions for Prototype 2. In theclosed position,
Prototype 3 measured 0.3% less dragarea than the baseline S-Works
Evade.
Figure 9 highlights the change in aerodynamic dragof the test
helmets in their vented and non-vented base-line states (DCdA) as a
function of their vent arearatios. For a similar vent area ratio,
the venting methodused for Prototype 3 is superior to Prototype 2
in terms
of aerodynamic efficiency. For a vented area ratiobetween 0.15
and 0.2, the change in aerodynamic dragfrom the non-vented
condition was more than threetimes higher for the Prototype 2
design than thePrototype 3 method of venting. Clearly for a given
ventopening area, the design of the vents can have a signifi-cant
impact on the aerodynamic forces acting onhelmets.
Discussion
Responsive helmets
While a number of studies have been conducted toexplore the
aerodynamic properties of commerciallyavailable bicycle helmets,3–6
this study includes novelprototypes that allow for the specific
testing of ventila-tion that has been designed to be modified in a
func-tional way. A previous study presented data about theeffects
of blocking ventilation holes of a Giro Atmoshelmet;6 however, this
does not consider a practicalapplication of this effect or the
opportunity to offer
0.226
0.228
0.230
0.232
0.234
0.236
0.238
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
CdA(
m²)
Vent Area Ra�o
Figure 7. The average drag area (CdA) for Prototype 3 at five
measured vent openings at a wind speed of 44 km/h.
Figure 8. Diagram showing the zones calculated as vent
area(orange with hexagon pattern) and non-vented area (dark
gray)for Prototype 3 with 20-mm vent opening.
Novak et al. 273
-
degrees of cover between open and closed. As a result,the
aerodynamic results for the prototype helmets inthis study must be
considered as part of a more com-plex system, rather than as simple
comparisons of drag,where lower drag is typically believed to be
better forcyclists.
For time-trial cycling inside a velodrome, wherethere is a
specified riding course within a closed envi-ronment, the links
between aerodynamic performance,athlete comfort and power output
will be more predict-able compared to outdoor cycling activities
where ter-rain, weather conditions, cycling speeds and
thephysiological cost of cycling are highly variable. Atslow speeds
riding uphill, aerodynamic drag forces areminimal, yet the energy
exerted by the athlete is high,and the need for cooling is
increased. However, imme-diately following a hill climb, a fast
decent typicallyoccurs where studies have shown that aerodynamic
effi-ciency is critical to athlete’s speed and race-time.3–6
Both the Kask Infinity and Bell Star Pro helmets allowriders to
adapt helmet properties at these times to pro-vide better air
circulation or reduce aerodynamic drag.However, riders must
remember to manually change
the setting each time, which could negatively affect
per-formance if forgotten. To date, there is no peer-reviewed data
regarding the effectiveness of these com-mercial helmet
designs.
The two responsive helmet prototypes in this studyare concepts
aimed to automate such ventilation adjust-ments using
electro-mechanical features. Such helmetsmay utilize built-in
sensors or tap into existing sensorsused on bicycles, such as
accelerometers and powermeters, to know what the rider is doing and
automati-cally adjust settings as needed to provide optimum
ven-tilation. A visual representation of how such a helmetmay adapt
is shown in Figure 10, and while the pat-terns for speed and power
may be somewhat simplified,they indicate how ubiquitous computing
may be able torecognize patterns and respond appropriately.
As previously noted, the electronics of prototype hel-mets have
been removed or simplified in order for windtunnel testing to be
performed, and the full effects ofsuch a system have not yet been
tested outside thelaboratory. However, the data from Prototype 3
showthat aerodynamic drag forces can be varied using anelectronic
control mechanism. Within the confines of
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
ΔCdA
(m²)
Vent Area Ra�o
Giro Advantage
Prototype 2Prototype 3 -
40mm
Prototype 3 -30mm
Prototype 3 -20mmPrototype 3 -
10mm
Figure 9. The change in drag area from helmets in their
non-vented states (DCdA) compared to their vent area ratios.
Figure 10. Common patterns during cycling that can be used to
control helmet ventilation.
274 Proc IMechE Part P: J Sports Engineering and Technology
233(2)
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this experimental study, the 3D printed prototype hel-mets have
achieved ;4% variation in drag forcesbetween their open and closed
states, which may beautomatically achieved in real-time using
ubiquitouscomputing. Evidence from other sports suggests
suchadaptable aerodynamic performance can be utilized inmany ways.
For example, Formula One racing cars fea-ture a drag-reduction
system (DRS) to assist with over-taking, while commercially
available vehicles, like theAudi TT, exhibit an automatically
adjustable spoiler,which aids in traction control at high speeds
and acts asan air brake during braking. Future testing of
helmetprototypes may consider such applications and arevaluable
considerations when understanding the resultsfrom this study as
part of a more complex system,rather than straightforward
comparisons of drag forces.
Limitations and future development
This pilot study has focused exclusively on the variationsin
aerodynamic drag between various helmet designs.When considering
the performance of a competitivecyclist this article only tells
part of the story. The fluidmechanisms leading to variations in
aerodynamic proper-ties of the helmet and the cyclist clearly
require furtherinvestigation. This pilot study has demonstrated
thepotential for the geometric properties of the helmet to betuned
to optimize rider performance criteria for variouscycling
scenarios. However, a detailed understanding ofthe aerodynamics of
helmet design and the flow interac-tions that occur between the
helmet geometry and theflow over a rider, where the majority of the
pressure dragacting originates, is lacking.
In addition to the aerodynamics, the thermal proper-ties of the
helmet and the ability of an athlete to regu-late body temperature
is impacted by helmet ventilationdesign. Future testing will allow
a more comprehensiveassessment of responsive bicycle helmet
abilities to reg-ulate thermal and aerodynamic properties by
modifyingventilation openings electronically. The study by Alamet
al.6 demonstrated a ;1.2 �C increase in head tem-perature at a wind
speed of 30 km/h when a helmet hadsome of its vents taped closed.
However, this tempera-ture difference disappeared at wind speeds of
;45 km/h and greater. The effect at speeds less than 30 km/h
isunknown as no data were collected at these lower windspeeds.
Similar insights are needed for responsive hel-mets to map the
changes in thermal properties as ventsopen, close and change form.
Future studies will alsoconsider the forces on the cyclist’s neck
as ventilationopens.
Prototypes will also need to consider equipment reg-ulations
with helmets being compulsory under Article1.3.031 of the
‘‘Clarification Guide of the UCITechnical Regulation.’’9 While
Prototype 3 highlightspotential opportunities for a cyclist in
terms of aerody-namic performance, UCI Article 1.3.031 states
that‘‘the use of mechanical or electronic systems in or onthe
helmet is also prohibited.’’9 Furthermore, Article
1.3.033 states that ‘‘equipment (helmets, shoes, jerseys,shorts,
etc.) worn by the rider may not be adapted toserve any other
purpose apart from that of clothing orsafety by the addition or
incorporation of mechanicalor electronic systems.’’9 While rules
frequently change,significant research is needed to validate the
safety ofelectro-mechanical helmets and the benefits to
athleteperformance and health.
Conclusion
This experimental research provides new wind tunneldata
regarding the aerodynamic properties of variousbicycle helmets and
venting systems, including proto-types for new forms of responsive
helmets. Both com-mercially available and prototype helmets were
used toinvestigate the impact that different venting methodshave on
aerodynamic performance. While a commer-cially available Giro
Advantage time-trial helmetrecorded the lowest drag forces,
blocking its vents wasfound to negatively affect aerodynamic
performance.The variation on aerodynamic drag between closed
andopen vent conditions was also compared between theprototype
helmets used in this study. Results showedthat the aerodynamic
performance of the helmets wasdependent not only on the size of the
vents but also onthe design and method used for ventilation. The
pro-totype helmets demonstrate the potential to automatecontrol of
adjustable ventilation to modify drag char-acteristics for a
variety of racing scenarios to optimizethe aerodynamic and cooling
properties usingembedded computing capabilities. Future studies
arein development to determine the link between vari-able helmet
ventilation systems and athlete perfor-mance measures, including
athlete cooling andaerodynamic efficiency.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interestwith
respect to the research, authorship and/or publica-tion of this
article.
Funding
The author(s) received no financial support for theresearch,
authorship and/or publication of this article.
ORCID iD
James Novak https://orcid.org/0000-0003-4082-4322
References
1. Epstein D. Are athletes really getting faster, better,
stron-
ger? http://www.ted.com/talks/david_epstein_are_athlet es_
really_getting_faster_better_stronger/ (2014, accessed 16
May 2014).2. Hamilton R. Le Tour de France: the greatest race in
cycling
history. West Sussex: Summersdale Publishers Ltd., 2013.
Novak et al. 275
http://www.ted.com/talks/david_epstein_are_athlet
es_really_getting_faster_better_stronger/
-
3. Alam F, Subic A and Watkins S. A study of aerodynamicdrag and
thermal efficiency of a series of bicycle helmets.In: Moritz EF and
Haake S (eds) The engineering of sport6: volume 1: developments for
sports. New York: Springer,2006, pp. 127–131.
4. Alam F, Subic A, Akbarzadeh A, et al. Effects of
ventinggeometry on thermal comfort and aerodynamic efficiencyof
bicycle helmets. In: Fuss F, Subic A and Ujihashi S(eds) The impact
of technology on sport II. Leiden: Taylor& Francis Group, 2008,
pp. 773–780.
5. Chowdhury H and Alam F. An experimental study onaerodynamic
performance of time trial bicycle helmets.Sports Eng 2014; 17:
165–170.
6. Alam F, Chowdhury H, Elmir Z, et al. An experimental studyof
thermal comfort and aerodynamic efficiency of recreationaland
racing bicycle helmets. Proced Eng 2010; 2: 2413–2418.
7. Weiser M. The computer for the 21st century. Sci Am1991; 265:
94–110.
8. Novak J and Loy J. Digital technologies and 4D custo-mized
design: challenging conventions with responsivedesign. In: Bryan
VC, Musgrove AT and Powers JR (eds)Handbook of research on human
development in the digital
age. Hershey, PA: IGI Global, 2017, pp. 403–426.9. Union
Cycliste Internationale. Clarification guide of the
UCI technical regulation. Aigle: Union Cycliste Internatio-nale,
2017, p. 47.
276 Proc IMechE Part P: J Sports Engineering and Technology
233(2)
