The crank scale and frame size proportion for the perfect athletic riding

Pedemonte is the premium Company which produces be-spoke carbon products featuring premium technologies. The Pedemonte production is located in Genova, in the north of Italy, in the Company there are 10 high qualified workers and advanced machinery.
The bespoke Pedemonte production of carbon frames and components for road, off-road and e-bike has an important technical advantage comparing to Asian monocoque carbon production.

By the Pedemonte factory it is possible to produce a carbon fiber frame with superior stiffness and lightness thanks to the possibility to select the best raw materials available in the market. The IWS technique introduced by the Pedemonte expertise, award winner of worldwide Shows and Competitions, has taken the cycling riding to to the next step.
On the other hand the Asian monocoque carbon production is based upon a chain production offering undifferentiated, standard frames at the lowest costs of labour and raw materials.

From a technical point of view the Asian carbon production tends to flat the offering in order to contain the available sizes therefore costs and at the same time maximizing profits. As a matter of fact Chinese factories usually offer a concentration of sizes to “satisfy” the average European public. This concept explains how the most proportioned sizes are those included between top tube from 53 to 58 cm. In these 5 centimeters are normally squized 3 sizes (S, M, L) and more or less all frame producers follow the same pattern in developing such geometries. The frame size standardization is extended to components which are proportionally to few body sizes but they cannot fit the needs of all cyclists.
First of all is the crank; in the market are available cranks from lenght from 170 to 175 mm but it is hard to find lengths under 170 mm or over 175 mm. In these 5 mm range are usually squeezed cyclists from height 150 to 200 cm. Moving from the center of the size chart and from the crank range, it is also difficult to meet the optimal and balanced proportions, this afflicts the correct bicycle fitting therefore the correct power transmission.
Pedemonte successfully exports carbon frames in Asia. It is recognized that Asian riders have specific heights under the worldwide average population. The Pedemonte tailor production got the favor of Asian cyclists thanks to possibility of customizing and adapting geometries to every height, even the extreme ones.
Sam Huang is the Pedemonte Official Taiwanese Distributor and Service Center, he is also the owner of the LAB BIKE store, and at the same time he is a careful bio-mechanic. Sam has recently introduced the concept of optimal selection of the crank length (CRANK SCALE) with particular focus to cyclists with body height under 165 cm. Cyclists under such height usually have some difficulties to ride the right frames suited to their morphology and the majority of the bicycle producers dont have in their range frames with top tube below 50/51 cm.
The crank scale and frame size proportion
This is because frames are manufactured by Chinese companies, and they tend to flatten the size of the offered frames.
Sam Huang, who is also the owner of a testing machine to evaluate the frame stiffness, he has found out that it is quite hard to offer the perfect bike fitting to his customers due to the lack of longer and shorter cranks. The major part of bike fitting slightly adjust the frame to the rider when it should be the opposite; the frame must be adjusted to the bicycle rider: active fitting.
With the wrong crank lenght it is possible to analyze the following considerations:
1) When the crank is in the top dead center (A) the femoral compression angle is excessively closed, forcing the cyclist to draw back with the torso, and at the same time the hip bone twists on the saddle. The flexors of the joint, mainly the ileum-psoas and the rectus femoris which, with the rising of the pedal from the lower dead point, tend to approach their maximum shortening.
2) When the crank is placed 90° (B), parallel to tarmac, it means in the best pushing moment, the knee angle is excessively reduced therefore the pedaling force is proportional to the thrust angle.
3) When the crank is placed in the lower dead point (C) the width of the angle of the knee is excessive, this determines an excessive lengthening of the pelvis and a consequent twist on the saddle
4) The cyclist struggles to keep the aerodynamic position, and at the same time loses pressure on the pedals. Those effects compromise the cyclist posture developing criticalities, therefore the overloads that result in pain and discomfort

The proper crank lenght combined to the Pedemonte bespoke frame allow the following fitting improvements:
1) Greater and better angle hip opening (A) with a consequent maintenance of the back leaning compression in aerodynamic position
2) Using both a shorter cranck and the correct higher saddle positioning, when the crank is positioned at 90° (B) respect to ground it allows the right leg angle; this process takes to a better leg thrust therefore more power on the pedal, and at the same time less effort and pain on knees
3) Shortening the pedaling diameter (C) it produces a better frequency and therefore greater thrust efficiency
4) Reduction of fatigue and heart rate, therefore less psychological stress

These elements show that the crank proportion to body height is an advantage concept:
1) Reduction of the contact interference between the front wheel and the foot 2) Increase of the knee opening angle by reducing the pressure on the knee itself and on the quadriceps, ensuring a higher quality of power 3) Increases the pedal peripheral speed and the pedaling frequency itself 4) Decreases the closure of the hip in the top dead center that benefits the maintenance of the posture of the back and therefore of the aerodynamic advantage, less painfully than the lumbar area 5) In the upper middle point the dorsal flexion of the ankle is reduced, ensuring greater power and less overload of the tendinous and muscular structures 6) The shorter crank is also lighter hence the inertia is partially reduced 7) The sum of the described elements ensure greater power, pedaling profitability and less physiological fatigue

The crank lenght size does not involves only differences in saddle height, but it is necessary to rearrange all frame tubing and geometry measurement, so we will have differences in the position of the center of gravity, centrality on the pedal, distension of the spine, etc.
Pedemonte offers the chance to amend the carbon frame geometry thanks to bespoke production. In particular, the change of the crank requires to replace the following specifications of the frame geometry:
1) BB Drop (A); or the distance between the bottom bracket and the straight line joining the two wheel hubs

2) STACK (B); that is to say the height of the frame, from the center of the bottom bracket to the horizontal coming from the upper center of the head tube

3) SEAT TUBE ANGLE (C) or vertical tube angle; this angle represents the inclination of the vertical tube which is conneted to the cyclist support: the saddle

Pedemonte allows to produce custom frames not only in color and graphics but also in geometry and dimensions, in order to allow cyclists to ride in the best efficiency and comfort conditions.



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