More efficient pedal stroke

The technical and technological developments in the cycling world over the past few years have been numerous, particularly for bicycles as a whole (frames, wheels, components, etc.). When talking about equipment for cyclists, however, such leaps in development have not been seen, particularly with shoes. In fact, shoe construction has remained unchanged for many years, with an upper (the top part of the shoe, often made of synthetic materials or leather) glued to the sole (stiff bottom part of the shoe) to which the cleat is attached.

Why is it that shoes are so important in cycling? Quite simply because they are the interface between the cyclist and the machine. You could put a well-trained cyclist on a very efficient bike, but if the connection between the two is poor, the system will not be the most efficient. And yet, if you take a look at top-level cycling today, you’ll see that the time differences have become smaller and smaller (for example, only 2 seconds separated the 1st and 2nd place finishers of Paris-Nice). It is thus important to optimize the performance of not only the machine and the athlete, but also the connection between the two.

By proposing our new Comète Ultimate shoe with its unique carbon shell + bootie construction (figure 1), the interface between cyclist and bike has never been so efficient.

Figure 1 – Mavic Comète Ultimate: the combination of a stiff shell and a soft bootie.

 

Pedaling, a motion more complex than it appears...

One pedal cycle corresponds to one complete revolution (360°) of the crank arm. The pedal cycle consists of a downstroke phase (forward), an upstroke phase (backward) and two transition phases also called the neutral points (top and bottom).

Even though the pedaling motion is constrained by the crankset, there are several different ways to pedal. You can just push down on the pedals, and you can also pull up on them (upstroke phase). The ultimate yet utopian goal would be to apply the same amount of power through the entire 360 degrees of the pedal cycle.

If we represent this force, or power, in a graph (Figure 2), here is what we can see:

Figure 2 – The evolution of power through one pedal cycle, represented by two pedaling patterns: basic and optimal.

 

The blue curve indicates asymmetrical pedaling, with drive phases when the crank arms are horizontal, and little (or no) effective force when they pass through the neutral points (when they are vertical). The orange line represents optimal pedaling, where the forces applied on the crank arm are constant throughout the entire cycle.

How does the Comète Ultimate shoe differ?

The Comète Ultimate shoe provides undeniable advantages. The first is directly linked to the shoe’s construction since it deals with stack height, which is the distance between the cyclist’s foot and the outsole (Figure 3).

The Comète reduces this height approximately 35%, from an average of 7 mm to just 4.5 mm. This limits the torque created between the foot and the pedal, which improves pedaling. This reduction in stack height thus provides a better connection between the cyclist’s foot and the crank arm.

Figure 3 – Illustration of the Comète Ultimate’s low stack height.

 

We have voluntarily chosen to concentrate on what occurs around the foot. From past tests, we have already been able to demonstrate the shoe’s rigidity and its unmatched transfer of power. Feedback was also very positive from our test riders, who noted a sensation of increased ankle freedom and “rounder” pedaling.

Ankle movement is very important while pedaling since it works to provide rounder and more fluid pedaling. We thus started by comparing ankle movement in the sagittal plane (plantar/dorsiflexion) using state-of-the-art motion capture technology. This technique (already widely used in animated films) consists of recording movement in three dimensions using small sensors placed on the articulations. This very precise method (< 1 mm) enables us to see ankle angulation in the sagittal plane during the pedaling cycle.

Figure 4 – Increased range of ankle motion with the Comète Ultimate.

 

Our results showed a significant increase (3 degrees) in the range of ankle movement, which was 19% on average when pedaling with the Comète Ultimate (Figure 4). This difference supports the fact that a very low shoe and very open construction provides more freedom for ankle articulation. This freedom thus enables the foot to work better while pedaling.

Does this have an impact on muscle function?

If we focus on ankle articulation, we can see that three main muscles are used to move the ankle (Figure 5):
The gastrocnemius (GAS) muscles, which permit plantar flexion (when the toes point down).
The tibialis anterior (TA) muscle, which permits dorsiflexion (when the toes point up).
The fibularis muscles (FL), which permit ankle eversion. These muscles provide lateral ankle stability while pedaling.

Figure 5 – Location and action of the muscles permitting the ankle to move.

 

By pedaling with a constant force (same resistance/velocity), we were able to compare the contraction of the muscles permitting ankle movement (GAS/TA/FL). Muscle contraction (in millivolts) is proportional to the muscle’s involvement in the movement. In other words, the more a muscle contracts, the more energy it expends. Figure 5 summarizes the results:

Figure 6 – Muscle contraction permitting ankle movement, according to shoe type.

 

One notes first that the muscles permitting the ankle’s flexion/extension (GAS/TA) contract up to 15% less when the Comète is worn. The same movement requires less muscle exertion, which makes it more efficient.
On the other hand, there is no difference with regard to the fibularis muscle (FL), which is a rather good result. In fact, the Comète Ultimate’s two-piece construction with carbon shell is able to provide a very low profile shoe that provides more ankle freedom (range of motion increased by 19%). Despite this, no loss of lateral stability was observed.

From a wider point of view, all these changes are going to affect our pedaling technique and drive efficiency. Let’s return to Figure 2, which shows the evolution of power during the pedaling cycle. We have the basic pattern with a large amplitude of power between the drive phases and neutral phases, and an optimal pattern with constant power throughout the entire cycle. Below, we have graphed what we measured while comparing pedaling with the Comète Ultimate and a high-end carbon-sole shoe (e.g.Cosmic Ultimate).

The test was performed at a constant force (250 watts). Once again, you can see the two drive/neutral phases for both shoes, but there is a 4.2-watt difference between them (Figure 7).

Figure 7 – Variation in power through a pedaling cycle according to shoe type (Comète Ultimate vs high-end carbon-sole shoe).

 

We observed that the power transmitted to the crankset through the neutral points was greater with the Comète Ultimate. This is due to the better application of force to the crank arms. Since the ankle has more freedom, the foot works with more efficient angulation and transmits a force which, although not greater, is more efficient. This thus accounts for the 4.2-watt difference through the neutral point.

Since this test was performed at a constant pedaling force (250 watts), all the power exerted to pass through the neutral point is power that won’t be applied in the drive phase. Put another way, by applying force more efficiently through the neutral points, less effort is required during the drive phase to remain at constant power. This clearly indicates much more efficient pedaling.

CONCLUSION

The unique two-piece construction offered by the Comète Ultimate provides several advantages. This combination of suppleness and rigidity, the result of five years of development, allows us to lower the shoe’s profile in order to free the ankle (range of motion increased by 19%). This increased freedom, coupled with the shoe’s overall rigidity, allows the foot to work:

  • more efficiently (gain of 4.2W through the neutral points + the shoe’s decreased stack height.
  • with less energy (ankle muscles work 15% less).

This is thus a product that allows the cyclist to be completely connected to the bike, for a perfect symbiosis between human and machine.

EXPERIENCE THE DIFFERENCE!

Mavic is offering you the opportunity to test the Comète Ultimate shoes with the Riding Is Believing program.

Book your test with one of the participating stores by clicking here right now!

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