Cycling Biomechanics
Working in colaboration with
Cycling biomechanics
Foot/pedal interface
The foot/pedal interface is the 'cornerstone' to effective bike fitting, yet it’s rarely reported in the cycling literature, that for an optimum outcome, findings from the pre-bike musculoskeletal screening process should subsequently be used to work with, and further enhance, the bikefit package. Failure to undergo effective screening by a qualified clinician may deprive the cyclist opportunity to optimise bike fit, and thus achieve those elusive marginal gains.
The slightest amount of malalignment can reduce power output
From the conception of the bicycle in the 19th century through to the modern-day race cycle, cycling has been a marriage between an adaptable human body and an adaptable machine. Cycling is very repetitive; during 1 hour of cycling, a rider may average up to 5,000 pedal revolutions. The slightest amount of anatomic malignment at the foot/pedal interface (forefoot tilt) can lead to injury and reduced performance - which we have measured as power output.
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Why screening should extend beyond Bikefit
The purpose of pre-screening is to identify potential biomechanical/anatomical problems, prevalent in many cyclists, in standing and walking (gait) that lead to foot dysfunction. If the foot is not providing a stable platform in day-to-day movements off the bike, it’s likely, in a vast number of cases, by not taking steps to control pronatory forces in gait, you are taking problems onto the bike, ultimately compromising the corrective measures made during bikefit. It’s widely accepted that the foot/pedal interface is the cornerstone to effective bikefit, but it’s rarely reported in the cycling literature, that for an optimum outcome, findings from the screening process should subsequently be used to work with, and further enhance, the bikefit package. Failure to undergo effective screening by a qualified clinician may deprive the cyclist opportunity to optimise bike fit.
Why use our screening service?
We have developed our very own unique and comprehensive biomechanical / anatomical screening protocol that has been published in popular UK and USA Cycling Performance magazines. Clinical screening of competitive cyclists is an area often neglected, undervalued, or misunderstood. However, this year 2011, Team Movistar have employed a biomechanic (Jon Irriberri) to screen their cyclists. Team HTC Columbia has adopted a similar method to identify potential problems. In order to treat something, we must first be able to recognize / diagnose it. Like any profession, this requires experience and specialist knowledge. We offer a complete comprehensive Bikefit package - see below.
Bikefit package
Ideally, a complete bikefit package should include pre bikefit screening and when necessary, advice and /or corrective measures implemented to control excessive pronation during gait activities. In cases where muscle or joint problems exist, a personalised musculoskeletal rehabilitation plan (click here for an example). If necessary, personalised rehab plans may be accompanied by manual therapy. Screening should involve a qualified clinician and when used effectively can significantly enhance the bikefit process.
We have experience and extensive research knowledge
We have more than 30 years experience in cycling. This includes; competing as a race cyclist, working as a Sports Therapists for various cycling teams, these include; GB road and cyclo-cross, and Manchester Wheelers. We have work with many of professional riders and elite amteurs over the years. We have undertaken an extensive review of the cycling biomechanics literature. We have also contributed to the dearth of published literature on this topic.
Modern carbon equipment excerbates alignment and forefoot problems
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Rigid carbon wheelsets |
Not something often referred to in the literature, but it’s highly likely modern technology, particularly the advent of carbon-fibre wheel and frame-sets and carbon soled shoes, exacerbates the problem of foot dysfunction. Whilst frames, wheels, cranks, pedals and shoes and so on, have all advanced and become significantly stiffer, the human foot remains unchanged. Jarboe and Quesda (2003) demonstarted that carbon-fiber shoes are 42% stiffer in longitudinal bending and 550% stiffer in three-point bending compared with plastic cycling shoes. Consequently, in a system that has very little flex for energy to dissipate, pressure on the foot increases considerably. While these rapid technological advancements, compounded by ever-improving rider fitness/strength provide for more efficient power transfer, they come at the expense of increased forefoot pressures causing the foot to collapse inwardly, which in turn, can be responsible for forefoot problems and increased pronation (24-26). |
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Rationale
Efficient, injury free cycling relies on rider symmetry throughout the entire pedal revolution. Strength and balance in the muscles situated in and around the pelvis are prerequisite to symmetry and paramount to efficient cycling, whether road, track or mountain biking. Symmetry represents a stable, level pelvis, with minimal pelvic motion (no rocking) and sound core stability. Similarly, there should be minimal sideways movement of the knee when pedalling. Excessive aberrant motion of the knee means the knee must travel further than is necessary through each pedal revolution - as depicted in the image by red arrows.This extra, but unwanted knee motion constitutes wasted energy and is potentially destructive on the structures of the kinetic-chain (foot, ankle, knee, hip, lower-back and neck). Power lossOur own unique research carried out in 2010 at Manchester Metropolitan University found a strong correlation between power output and cyclists with varying amounts of forefoot varus. Interestingly, those with the highest levels of forefoot varus demonstrated increased mean peak power outputs of approximately 10% while performing 30 second maximum anaerobic effort. Considering the high prevalence of forefoot varus (87%) found amongst cyclists, these findings may have implications across the cycling population. In summary, cyclists presenting with higher levels of forefoot varus potentially have the most to gain. A summary of our findings were published in Cycling Weekly Jan 2011. Click here for the summary Click here for the full published article |
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What is the cause of asymmetry?The foot/pedal interface is the mechanical link between the leg and the cycle, and consequently, the point at which asymmetry most often arises. Less than (<) 10% of the population has a neutral foot (2-5). When translated into cycling terms, < 10% of cyclists have a perfect foot position when placed on the pedal (5,6). Reduced cycling performance and overuse injuries, particularly knee related, are frequently linked to the anatomic structure of the foot (i.e. excessive pronation). This is because the structure and function of the foot dictate how effectively pedal forces are transmitted via the foot/pedal interface down to the cranks, and potentially, how deleterious forces are transmitted up the kinetic-chain – impacting on the knee, hip, pelvis, lower back and neck. During one hour of cycling, a rider may average up to 5,000 pedal revolutions. The smallest amount of malalignment at the foot/pedal interface, whether anatomic, biomechanical or mechanically related, creates asymmetry – which often leads to overuse injury and impaired performance. In support of these claims, studies demonstrate excessive foot pronation can compromise core and pelvic stability and/or create postural issues (7-14). |
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Case Study
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Leg-length differences (LLD) which can be either anatomic or functionalAnatomical differences, which are true LLDs, result from an actual anatomic shortening of one or more of the bones of the lower extremity. Whereas, functional LLD is not a true leg-length difference, it usually occurs as a result of muscular weakness or inflexibility at the pelvis or foot and ankle complex. |
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What is pronation?
Pronation is when the foot rolls inwards and is considered a normal and necessary motion for efficient gait. Excessive pronation is when the foot rolls in too far, which can result in knee problems (17-22), pelvic and core problems (7-14), and reduced cycling performance (23-26). Excessive pronation can be unilateral (one foot) or bilateral (both feet).
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Forefoot varus and tibial varum are considered to be the two most common causes of excessive pronation in cyclists. In gait, forefoot varus, tibial varum and ankle equinus are the main culprits of excessive pronation. Forefoot varus is a forefoot-rearfoot alignment problem; the 1st MTP joint (big toe) is elevated from the pedal with the rearfoot in a neutral position - image on the left. Tibial varum (bowlegged) is represented by the natural bowing of the lower third of the tibia - image on the right. Both of these two conditions mean the foot must roll inwards to enable effective contact with the pedal surface. The greater the levels of forefoot varus and/or tibial varum, the greater the level of pronation. |
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The evolution of clipless pedal systems
In 1984, Look the French-based ski binding manufacturer first tested a rigid float-less clipless pedal with the help of professional cyclist Bernard Hinault. This clipless system was introduced to the market in 1986. However, this rigid float-less system placed undesirable stress on the knees. In 1987, Jean Beyl invented the Time pedal system, known as Bioperformance, which allowed free rotational float and some lateral motion of the foot. At first the Bioperformance system received much criticism from competing pedal manufactures, alleged claims of power loss due to float were proved incorrect after research studies demonstrated otherwise. Professional cyclist quickly adopted the system, and subsequently most manufactures modified their pedal systems to include varying degrees of rotational float (37).
Some riders need more float
Self-centering |
Most modern-day clipless pedal systems (e.g. Shimano, Time, and Look) use spring loaded devices which employ a self-centering mechanism which allows varying degrees of rotational motion (typically 4° to 8°) against increasing resistance, this brings the shoe back to the preset neutral alignment. We believe these systems are suitable for the majority of riders with limited biomechanical malignment caused by problems such as tibial torsion. However, in a minority of cases where riders present with greater biomechanical problems, thus often need more rotation to accommodate misalignments. The Speedplay pedal offers 0° to 15° of free float rotational motion. Compared with its competitors, the Speedplay can offer two benefits; increased but adjustable float, and free float – meaning the foot does not have to work against spring loaded resistance. |
Free rotational float |
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Tel: 01200 427457 | email:nickdinsdale@fsmail.net