Humans are asymmetrical beings. Yet bikes & pedal systems are designed symmetrically which can create biomechanical challenges for the lower extremities of a cyclist. In this blog we will look at the most crucial, and often misunderstood, connection point on the bike: the foot/pedal interface.
On Physics Of Cycling, it is said that “At the start of the ride, the cyclist initially has chemical energy stored in his/her body as a result of the cyclist’s food intakes. This chemical energy in the cyclist is then converted to kinetic energy on the bike pedal due to the cyclist applying a downward force upon the bike pedal. As a result, the kinetic energy upon the bike pedal is transferred to the cogwheel on the bicycle’s backside via the bike chains attached to the pedal. The cogwheel begins to output motor energy onto the back bike wheel, which enables the bicycle back wheel to move in a clockwise direction.” In other words, every watt of power generated in the key cycling muscles, is transferred in to forward motion of the bike via the foot/pedal interface.
One of the most important and overlooked aspects in bike fittings is the tilt and angle of the forefoot. Studies show that 96% of all cyclists are misaligned in their connection to the bike, decreasing comfort and efficiency. Of these cyclists, most have what is known as a Forefoot Varus (the inside of the foot tilts upward) – for runners who may have had a “gait analysis“, they will be familiar with terms such as ‘pronation’. This causes a misalignment as soon as you clip into a pedal because the pedal is flat, and solid carbon fibre. This misalignment can also lead to pain and/or numbness in the feet, with reports suggesting up to 54% of cyclists suffer from such (ref 1).
A specific tilt adjustment where the cleat/shoe meet can resolve the most common painful or numb areas of the feet. Cleat Wedges, or In-The-Shoe Wedges, are stackable to fine-tune your unique forefoot tilt, which can be measured by a professional. They are specially designed to fill the gap between the natural angle of your foot and the flat, hard pedal. This allows your foot to maintain its natural position – not change it.
This can also have dramatic effects further up the chain, as, whereas with running the foot is a slave to the hip, in cycling, the knee becomes a slave to the foot. If your foot is forcing itself flat in the solid shoe, the knee will follow. Have your cycling friends ever commented on your knees deviating in toward the frame on your rides together? Do you suffer from knee pain in the low impact sport that is bike riding?
And its not all about wedging the foot; the fore-aft (front-back) position of the cleat, the width of the spindle, the medial-lateral (left-right) position and the rotation (or float) of the cleat will all have dramatic effects on where both the foot and the knee will travel in each single revolution – of thousands at a time.
If you are suffering from foot or knee issues on the bike, or would like to know more about increasing your efficiency, more information can be found here.
Journal of Science and Cycling 2012; 1(2): 28-34