Science & Sports (2012) 27, e55—e61
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ORIGINAL ARTICLE
Antero-posterior position of the cleatfor road cyclingPosition antéro-postérieure de la cale pour le cyclisme sur route
J. Ramos Ortega ∗, P.V. Munuera, G. Domínguez
Centro Docente de Fisioterapia y Podología, Department of Podiatry, University of Seville, C/Avicena s/n, 41009 Sevilla, Spain
Received 28 September 2010; accepted 7 December 2011Available online 20 January 2012
KEYWORDSEnglish: cleat;Cycling;Foot;Lower limb
SummaryObjective. — This work aims at determining the antero-posterior position of the cleat based onvarious morphological characteristics of the cyclist’s lower limb.Method. — Two tests were used to quantify this position: a photograph-based one and aradiograph-based one. Both, the photograph and the radiograph were digitalized to enablemeasurements by means of the software AutoCAD® 2006. Two linear regression models wereconstructed from the variables cleat/first metatarsal distance and tip/cleat distance, whichwere invalidated by the low squared-R coefficient value (0.106 and 0.057, respectively).Results. — Participants presented almost constant values of 3.6 ± 0.8 cm for the cleat/firstmetatarsal distance and 0.43 for the tip/cleat distance. As the distance from the base ofthe cleat to the pedal spindle is 3.6 cm, it may be stated that the pedal spindle may coincidewith the head of the first metatarsal by positioning the base of the cleat at 43% of the lengthof the shoe measured from its distal end.© 2011 Elsevier Masson SAS. All rights reserved.
MOTS CLÉSCale ;
RésuméObjectif. — Ce travail vise à déterminer la position antéro-postérieure de la cale sur la base dediverses caractéristiques morphologiques des membres inférieurs du cycliste.
Vélo ;Pied ;Membres inférieurs
Méthode. — Deux essais ont été utilisés pour quantifier cette position : une photo et une radio-graphie de base. Les deux, la photographie et la radiographie ont été numérisées afin depermettre des mesures au moyen du logiciel AutoCAD® 2006. Deux modèles de régression
à partir des variables distance cale/premier métatarsien et dis-
linéaire ont été construits tance pointe/cale, qui ont été invalidées par la faible du coefficient R (respectivement 0,106 et0,057).∗ Corresponding author.E-mail address: [email protected] (J. Ramos Ortega).
0765-1597/$ – see front matter © 2011 Elsevier Masson SAS. All rights reserved.doi:10.1016/j.scispo.2011.12.004
e56 J. Ramos Ortega et al.
Résultats. — Les participants ont présenté des valeurs quasi-constantes de 3,6 ± 0,8 cm pour ladistance cale/premier métatarsien et de 0,43 pour la distance pointe/cale. Comme la distancede la base de la cale à l’axe de la pédale est de 3,6 cm, on peut dire que la pédale de brochepeut coïncider avec la tête du premier métatarsien par le positionnement de la base de la caleà 43 % de la longueur de la chaussure mesurée à partir de son extrémité distale.
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. Introduction
he most common injuries in the cyclist are those affectinghe knee, some 25% of all the non-traumatic injuries suffered1,2]. Cyclists of any category might be affected, but theseroblems are most frequent among those of a high level,ecause of the substantial distances they cover in training3]. Such injuries can range from slight discomfort on goingown stairs or after a long ride, to the impossibility of ped-ling. As far as the authors are concerned, there have beenew data recorded during recent years on the incidence ofiscomfort in cyclists’ knees. The most frequent types ofnjury due to overloading in cycling result in femoropatellarr latero-medial pain in the knee joint [1,3—5]. Differenttudies aimed at preventing these problems have analyzedhe elements giving the most exact alignment in the fitetween cycle and cyclist for each rider [6,7]. The heightf the saddle and handlebars, and the length of the crankre the most common but, according to the authors’ knowl-dge, there is no research on the exact position of the cleatn the shoe. Cycling injuries may also be the result of mis-lignments between cyclist and bicycle. It must be takennto account that the pedal restricts the foot movement to
circular pattern in the sagittal plane of motion, and thathe shoe/pedal fixing systems do not allow movements ofhe two parts in the frontal or transverse planes. If the lowerimb does not describe a normal trajectory during pedaling,orces generated in pedaling may add loads to the jointshat are not associated to the propulsion of the cycle [8].n incorrect antero-posterior position affects the antero-osterior forces of the knee [9—11].
Shoe/pedal interaction is crucial for an effective trans-ission of the forces generated by the cyclist to the bicycle,
o that the alignment of these parts is considered an impor-ant factor in the management and treatment of injuriesaused by overloading of the knee [12]. Currently, as far ashe authors are concerned, there is no consensus on the idealongitudinal position of the cleat to prevent these injuries.ome authors refer to an adjustment based on the coin-idence of the pedal spindle with the head of the secondetatarsal [9,11,13,14], whereas others claim that it shoulde with the head of the first metatarsal [7,15,16].
This work is designed with the following aims:
to analyze the exact position of the cleat for each cyclist,according to some variables measured on their feet (thatis, metatarsal index, forefoot adduction, the distancefrom the cleat to the head of the first metatarsal, andthe distance from the distal end of the shoe to the base
of the cleat);to determine which of the longitudinal variables (dis-tances) is the most important in the adjustment;
cdwt
s droits réservés.
to construct regression models enabling adjustment of theposition of the cleat for each cyclist by using these varia-bles. The null hypothesis of this study is that the positionof the cleat could be the same for all cyclists, as thevariables studied do not have any influence.
. Methods
he target population of this study consists of cyclists whose clipless road bike pedals and practice cycling in an inten-ive way (more than 5000 km per year). The sample size wasalculated with the software nQuery Advisor 4.0, accordingo the number of variables to relate (between 2 and 5), thexpected values of the coefficient of multiple correlationranging between 0.14 and 0.68 in a pilot study carried outreviously), a value for � of 5%, and a 1-� power of 80%.hese data gave a size of 88 feet. The sample consisted of4 participants (88 lower limbs: 44 right and 44 left). Sevenarticipants were women and 37 were men, with a mean agef 34.4 ± 11.1 years old. This study was carried out duringctober, November and December 2008. Each participantave written consent to take part in the study, and the studyas approved by the Experimental Ethics Committee of theniversity of Seville.
It must be pointed out that the authors refer always toeet rather than persons, as the anthropometric variables ofhe two feet (right and left) may be different in the samearticipant, and in clinical practice the need to perform aeparate examination to each foot is frequent. As Menz andunteanu explained [17], the main conceptual and statisti-al problems generated by this type of approach arises whenhe inferences derived from the studies are made in relationo people, having used feet as the unit of analysis. As theim of this study is to analyze and relate the characteristicsf the lower limb and the cleat, the authors used feet as unitf the sample, and not the participants. Thus, the sampleonsisted of 88 feet.
The inclusion criteria were the following: cyclists agedore than 20-years-old [18—25], not having suffered severe
raumatisms or surgical operations on the lower limb, notaving suffered injuries caused by overloading the lowerimb during (at least) the previous year, using automatic ped-ls Look®, and with a sporting intensity of a minimum 5000ilometers per year.
The variables were recorded using two tests: a photo-raph and a radiograph. For the first one, a Cyber-shotSC-P120 digital camera (Sony, San Diego, U.S.A.) was used,ith a resolution of 5.1 mega pixels and an optical zoomapacity of 3x, placed on a tripod at a ground-to-camera
istance of 1 meter, completely vertical to the shoe, whichas resting on the ground and centered on the screen suchhat the distal and proximal ends of the shoe exactly fitted
e57
For the qualitative variable metatarsal index [36,37],there were 26 cases of plus index, 60 of minus index, andtwo of plus-minus index. The shoe size presented minimumand maximum values of 39 and 46 respectively (measured
Antero-posterior position of the cleat for road cycling
the image frame. The dorsoplantar radiographs were madeusing a Sedecal SPS HF-4.0® X-ray equipment. The X-ray tubehad an inclination of 15 degrees to the vertical [26], anda tube-to-plate distance of 1 meter, according to the cri-teria of the Measurements and Terminology Committee ofthe American Orthopaedic Foot and Ankle Society [27,28](AOFAS). Radiographs were taken under weight-bearing con-ditions, as this is the constant state of the foot in this sport[29]. The radiological parameters employed were 65 Kv and10 mAs. Because of the radiotransparency of the piece understudy (the cleat), it was decided to place a rigid metalelement at its base to act as a reference in the imageof the shoe when fixed on the pedal. The radiograph thusobtained was digitalized, using a scanner able to exploreimages on negative films (EPSON EXPRESSION 1680 Pro®,Seiko Epson Corporation, Nagano, Japan) to create a digi-tal image. Measurements were made on the digital image,using the software AutoCAD® 2006 (Autodesk Inc, San Rafael,California). The protocol of digitalization and measurementof the radiographs has previously been used in other studies[30—35].
The variables studied (and their units of measurement)were age (years old), gender (male or female), annualdistance ridden (kilometers), weight (kilograms), height(centimeters), body mass index (BMI), angle of adduction ofthe forefoot (degrees), metatarsal index (plus index, minusindex, plus-minus index), [36,37] shoe size (Paris Point Sys-tem; 1 Paris point = 6.67 millimeters), distance between thecleat and the first metatarsal (centimeters), and distancebetween the tip of the shoe and the base of the cleat(%).
The angle of adduction of the forefoot was measured onthe radiographs. It was formed by the intersection of thelongitudinal axis of the second metatarsal with that of theminor tarsus [38—41]. The cleat/first metatarsal distance(Fig. 1) was also measured on the radiograph, as the distancefrom the first metatarsophalangeal joint to the base of thecleat. However, the tip/cleat distance (Fig. 2) was measuredon the photograph, as the ratio between the distance fromthe distal end of the shoe (tip) to the base of the cleat, andthe total length of the shoe.
Data were analyzed by using the software SPSS 15.0for Windows (SPSS Science, Chicago, Illinois). A statisti-cal purification was performed to detect atypical values.The Kolmogorov-Smirnov test was used to check whetherthe data followed a normal distribution; the results of thistest showed a normal grouping of the data, validating theuse of parametric tests. A Student t-test for independentsamples was performed on the dependent variables depend-ing on the side (right-left) to test the homogeneity of thesample. Lastly, linear regression models were constructedusing the cleat/first metatarsal distance as dependent vari-able in one model, and the tip/cleat distance in anothermodel, and shoe size and metatarsal index as predictorvariables. The value of P was considered significant whenP < 0.05.
3. Results
The values of age, weight, height, BMI, and annual kilome-ters, of all participants are shown in Table 1.
Figure 1 Cleat-first metatarsal distance.
Figure 2 Tip-cleat distance.
e58 J. Ramos Ortega et al.
Table 1 Age, weight, height, BMI, and annual kilometers, of all participants.
N Minimum Maximum Mean SD
Age (years) 88 19.00 62.00 34.41 11.09BMI 88 18.62 26.99 23.20 1.92Height 88 157 184 172 008Weight 88 52.00 84.00 68.79 7.92Annual km (km) 88 5000 30.000 12470.45 6243.58
Table 2 Mean, typical deviation, and confidence interval to 95% for the quantitative variables.
Confidence interval to 95%Variable Media ± DT Lower limit Upper limit
Adduction of the forefoot (degrees) 13.3 ± 0.4 12.4 14.2Cleat/first metatarsal distance (cm) 3.6 ± 0.8 3.4 3.7
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Tip/cleat distance (%) 0.43
s Paris points). Regarding the remaining variables, mean,tandard deviation, and lower and upper limits for a confi-ence interval of 95% are detailed in Table 2.
The results of the Student t-test for independent groupsn the dependent variables depending on the side (right andeft) did not show significant differences in the sample, noror the variable cleat/first metatarsal distance (P = 0.251),or for the tip/cleat distance (P = 0.246).
The linear regression was intended to illustrate theffects of the independent variables on a dependent vari-ble, so that two models were constructed: one of themy taking the cleat/first metatarsal distance as dependentariable, and the other one taking the tip/cleat distance asependent variable.
.1. Cleat/first metatarsal distance model
and R2 values for this model were 0.326 and 0.106, respec-ively (P = 0.002). The linear regression procedure (Table 3)ielded the following equation to determinate the position
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Table 3 Correlation coefficient. Model 1.
Model Non-standardized coefficients
B Typ. Error
Constant —22.624 18.240
Shoe size 1.379 0.431
Elements in bold are the coefficients of the equation. The first is the cofor the model: first metatarsal distance.
Table 4 Correlation coefficient. Model 2.
Model Non-standardized coefficients
B Typ. Error
Constant 0.618 0.084
Shoe size —0.005 0.002
Elements in bold are the coefficients of the equation. The first is the cofor the model: tip/cleat distance.
0.42 0.43
f the cleat: first metatarsal distance = —22.624 + (1.379hoe size).
.2. Tip/cleat distance model
and R2 values for this model were 0.238 and 0.057, respec-ively (P = 0.025). The linear regression procedure (Table 4)ielded the following equation to determinate the posi-ion of the cleat: tip/cleat distance = 0.618—(0.005 shoeize).
. Discussion
he position of the cleat is a possible risk factor in theevelopment of knee injuries caused by overloading. The
ncidence of this type of alteration is approximately 25%2,42] and the etiology has not been clearly described yet.lthough numerous adjustments exist between cyclist andachine, there are no accepted scientific criteria for theConfidence interval for B to 95%Lower limit Upper limit
—58.884 13.6360.522 2.236
nstant and the second is the coefficient of the shoe size variable
Confidence interval for B to 95%Lower limit Upper limit
0.450 0.785—0.008 —0.001
nstant and the second is the coefficient of the shoe size variable
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Antero-posterior position of the cleat for road cycling
positioning of the cleat. In this work, the authors haveattempted to contribute to establish individualized crite-ria that help adjust the cleat to avoid this type of injuries.Furthermore, the results could be used to establish specificadjustments of the cleat for the rehabilitation of certaininjuries of the lower extremity.
Ericson et al. [9,11,13] studied the changes of momentproduced in the lower limb when the position of the cleatwas altered, and they established two positions: a forwardone, in which the pedal spindle coincides with the head ofthe second metatarsal, and a rearward one, 10 cm behindthe aforementioned one. They found that the forward posi-tion generated an increase in the dorsiflexion of the ankle(five degrees), in the moments of the ankle, and in the activ-ity of the soleus muscle. However, the rearward position ofthe cleat produced an increase of seven degrees in the move-ment of the hip, an increase of three degrees in that of theknee, and an increase of the stress suffered by the anteriorcruciate ligament. Mandroukas [14] also studied the reper-cussion of cleat displacements in lower limb, and found thatpedaling was more effective with a forward position of thecleat.
On the other hand, different authors recommend placingthe cleat at a position in which the spindle coincides withthe head of the first metatarsal. Vey Mestdagh [7] empha-sized the importance of determining the exact position ofthe cleat on the cyclist’s shoe because, for the lever formedby the midfoot and rearfoot to be useful, the pedal spindlemust be positioned beneath the head of the first metatarsal.Callaghan [16] and Ruby [15] maintain that the most com-monly accepted position for the foot in relation to the pedalis an alignment of the head of the first metatarsal with thepedal spindle.
Sanderson et al. [43,44] analyzed the distribution of plan-tar pressures during pedaling, and showed that the morethe resistance, the higher the percentage of pressure underthe zone comprising the head of the first metatarsal andthe hallux. Moreover, it has to be taken into account thatthe antero-posterior position of the foot (together with theheight of the saddle) alters the length of the lower extrem-ity.
In the present work, two models of linear regression havebeen constructed: one based on measurements from a radio-graph, and the other one based on those from a photograph.In the first one, the dependent variable was cleat/firstmetatarsal distance, and metatarsal index [36,37,45] andshoe size were used as independent variables. In this model,the value of R2 indicated that it was not very useful, so itwas rejected, allowing the statement that the longitudinalposition of the cleat will not be affected by either the typeof metatarsal index [36,37] or the cyclist’s shoe size. Allfeet, independently of the type of metatarsal index [36,37],presented very similar values for the cleat/first metatarsaldistance, with a mean value of 3.6 ± 0.8 cm (Table 2). Inthis type of pedal, the spindle is always 3.6 cm from thebase of the cleat. This means that there is a constantfor the position of the cleat with respect to the head ofthe first metatarsal, according to the studies of Sanderson
[43,44], Ruby [15], and Callaghan [16]. There is the samedistance from the base of the cleat to the head of the firstmetatarsal and to the pedal spindle, so it tends to be aconstant.tepi
e59
In the second model, based on the tip/cleat distance,t was used the same independent variables (metatarsalndex and shoe size). This model yielded R2 values evenower than the first one, meaning that the relative posi-ion of the cleat does not vary with the shoe size. Fromhe data of the variable tip/cleat distance, the mean valueas 0.43 and, as it was confirmed in the first model theffect of the spindle over the head of the first metatarsal,he cleat can be exactly placed, by multiplying the cons-ant 0.43 (variable tip/cleat) by the length of the cyclist’shoe (centimeters), so that the pedal spindle will lay overhe head of the first metatarsal. These data were in concor-ance with those obtained by Gonzalez and Hull [46], whoetermined that the ideal position is that in which the cleats at 54% of the length of the shoe measured from theearfoot, that is, at 46% from the distal end. This coulde used in future works to create a scale containing thexact distance from the distal end for each shoe. Thisould help avoid potential injuries caused by a poor adjust-ent, such as Quadriceps overloading (due to a rearwardosition) or Gastrocnemius overloading (due to a forwardosition) [7], and excessive tension on knee ligaments [47].nother practical implication of the results of this studyould be their application to help in techniques of reha-ilitation — thus, knowing the position of the cleat for aertain cyclist, the tension of an damaged Achilles ten-on could be regulated by using the results of the studyy Ericson et al. [48]; or working the dorsiflexion of aosttraumatic ankle by moving the cleat rearward to areater or lesser extent; or helping in the rehabilitationf a knee with anterior cruciate ligament injuries or chon-romalacia patellae, by bringing the cleat forward [49,50].his is because, by varying the longitudinal position of theleat, the lever arm of the lower limb is altered, chang-ng its ranges of movement and muscular actions. Futureesearch could be aimed at testing whether these variationsn the position of the cleat would yield the proposed resultsegarding the rehabilitation of injuries in the cyclist’s lowerimb.
The authors consider that this work has some limita-ions, as the low number of women in comparison to thatf men, or the use of only one type of pedal, as there arearious models available in market. Future works could tryo cast new light on this issue by increasing the numberf female cyclists, as well as by using different types ofedals.
. Conclusion
he antero-posterior adjustment of the cleat does notepend on the shoe size or the metatarsal index, but it is
constant, according to the results of the present study.f the base of the cleat is set at 43% of the length of theyclist’s shoe (measured from the shoe distal end), the basef the cleat will be at 3.6 cm from the head of the firstetatarsal, which coincides with the pedal spindle. This
he first metatarsals on the pedal spindle. By knowing thexact determination of the cleat position, it could be pro-osed and studied progressive rehabilitative treatments ofnjuries to the knee or ankle.
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isclosure of interest
he authors declare that they have no conflicts of interestoncerning this article.
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