In a sport where efficiency is king and power transfer is the number-one goal, it’s often drummed into us that stiffer equals better. Top of the list where this mantra has been repeated almost ad nauseam is the cycling shoe.
Cycle any appreciable distance in a normal shoe or trainer, as we all have, and it becomes quickly apparent that a sole designed around walking does not make for a comfortable riding experience.
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This is why, as cycling shoes evolved, one of the primary goals was to create a stiffer sole to limit discomfort.
As cycling advanced so too did our understanding of efficient power transfer leading to the role of the cycling shoe becoming more than just about comfort.
Stiffness comes from the material the sole unit is crafted from. Less expensive entry-level shoes mainly utilise a nylon or injection-moulded plastic sole.
Carbon-fibre, as in most areas of cycling, is the material of choice for all high-end shoes. Carbon enables the sole to be stiffer, lighter and much thinner.
Is stiffness the sole goal?
The biomechanical impacts of cycling have been studied at length, mostly in a bid for improved performance but also to help prevent injury. Most shoe companies and bike-fit experts agree that while sole stiffness is undoubtedly important, other factors are equally crucial.
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Phil Cavell, founder of CycleFit and bike-fitter for Trek-Segafredo, explains: “The actual shoe brand or material of the base of the shoe is entirely subservient to fit and support considerations.
“Our hierarchy [for shoe choice] is: the fit of shoe based on foot length, foot width, and volume of foot; then the support of the static foot within the shoe through custom footbeds or orthotics, before finally considering a shoe brand or material.”
In simple terms, all feet are unique.
A manufacturer could produce the stiffest shoe on the market but if it doesn’t fit an individual’s feet then performance will suffer. In Cavell’s opinion: “This is equally as inefficient as a highly flexible shoe.” This inefficiency is brought about by losses in potential energy, typically caused by continued foot movement or even worse, discomfort and pain.
Specialized has long been an exponent of a holistic shoe approach through its Body Geometry fit designs. For the Californian company, sole stiffness is very much only one part of performance cycling footwear.
It does recognise, however, that if everything else is equal (fit, upper, retention, materials, and construction) then sole stiffness, for the majority of riders will be seen as a performance benefit.
Is stiffest always best?
Giro is a brand that acknowledges that stiffness needn’t be the primary consideration. Rather than using a ‘stiffness index’ to rate its shoes, rider style, preferences and price are the deciding factors. Giro UK manager Stuart Hayes explains that while it produces the super-stiff ACC carbon sole, most Giro-supported high profile riders choose the lighter but less stiff SLX outsole.
Not all riders are looking for the stiffest interface.
An individual’s riding environment can make all the difference. A track sprinter might look for the stiffest shoe with little compromise, but for beginners or those that race cyclo-cross and venture off-road, a little flexibility is important for overall foot health.
For most road cyclists though, Madison and Shimano’s Mike Anderson sums it up best: “Essentially if everything is in perfect alignment and the foot is supported properly by the insole then stiffer will always be better.”
Dave Alexander, body geometry trainer at Specialized
“A stiffer sole unit has the ability to support the performance features of a shoe, rather than deform or flex under load and potentially lose some of those benefits.
As shoe, bike and pedal technologies have improved, the emphasis has been on ‘lighter and stiffer’ which is a mantra that looks great on paper and in numbers. Comfort, however, is a metric that is much harder to measure as it is more subjective to each individual rider.
“When a flexible structure (such as the foot) is turned into a lever (such as via the femur) there is always the chance that some riders will not like their feet to be so directly connected to the pedals. In effect, the stiffer the shoe is, the more focused the pressure will be through the sole and of course, the rider will feel that.
“However, I would conclude that the above rider is in the minority and there are always plenty of options for a ‘less stiff’ sole, whereas the stiffer sole can potentially become even more tuned in to each individual rider’s needs, especially when supported by a bike-fit.”
There is no doubting that, on paper, the stiffest sole units will be the most efficient and performance enhancing. However, it is equally important to acknowledge that this performance will go to waste if the rest of the shoe doesn’t fit.
More than with any other piece of equipment, it is vital to opt for the shoes that work for you.
Get this right and stiffer will almost certainly equal better.