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How to know the size of connecting rods you need

How to know the size of connecting rods you need

Carrying longer or shorter connecting rods can mean the difference between having a more efficient or more inefficient pedal. But being wrong with the connecting rod length can involve suffering discomfort during your outputs or provoking an injury. To the one that happens with other elements, such as the shell or the handlebar, the connecting rod is one of The bicycle components that can be modified to obtain a better performance in each of your outputs and prevent injuries. The connecting rods are responsible for transmitting the energy of each pedal blow to the pedalier axis and from this one to the wheels through the chain. That is, the connecting rods are responsible for transforming the strength of the pedaling in motion. [IRP posts = "87" name = "How to choose the correct bicycle size"] Choosing a correct connecting length is fundamental. The improvement that you can introduce in your connecting rods is determined by its size, specifically by the length of its arm, which is the section that joins the pedal with the pedalier axis. You can also get an improvement in your performance by choosing some rod of a lighter material, such as carbon, or with some special characteristics, as with hollow connecting rods. However, weight savings between one and the other rods, average encryption in 200 grams, will not be as important as in other components, such as wheels or handlebar.

Why change the size of the connecting rods?

Cycling shoes Choosing some rods of one size will give you certain improvements in your way of pedaling, although not your pedal will be more powerful. The latest biomechanical studies related to connecting rods, especially the teacher Jim Martin of the University of UtahThey have determined that the increase in power is very scarce with change, less than 4% from one end to another (120 to 220 mm). A much broader range than the most used measures in the market (165 to 175 mm).
Pedaling with the ideal rod size avoids the appearance of muscle discomfort
The improvement, in practice, translates into a superior adaptation of your way of pedaling to the joints involved, mainly hip, knee and ankle. Pedaling with the ideal connecting storage size avoids the appearance of muscle discomfort, by adapting the movement of these joints to your pedaling shape. However, and depending on the praticated modality (road or Mountain Bike), Opt for one or another measure will add extra improvements in aspects such as acceleration or passage through obstacles.

What connecting sizes are available?

Measuring tape In the current market two connecting connections have been imposed in a standard manner: 170 mm and 175 mm. The first is the most frequent in bicycles of s and m sizes, while the second is more common in large sizes, such as L or XL. But we can also find in the market of larger or small measures, as well as other intermediates (180 mm, 172.5 mm or 165 mm). Thus, in general, the choice of one or another is determined by the carving of the cyclist.

Connecting rod sizes according to bicycle size

In the following table we can see a ratio of connecting rod sizes depending on the size of the bike or cyclist's height (Source: Burke, Edmund R. High-tech cycling):
Height / bicycle size Connecting rods
Less than 152 cm / xs 160 mm
Between 162 and 168 cm / s 165 - 167 mm
Between 168 and 183 cm / m, m-l 170 mm
Between 183 and 189 cm / l 172.5 mm
Between 189 and 195 cm / xl 175 mm
More than 195 cm / xxl 180 - 185 mm
However, this rod size/size is the traditional one, which have adopted brands generalized to manufacture their models. But the progress of biomechanics applied to cycling of recent years, with the publication of different specialized studies on the subject, contradict this formula, giving more importance to the length of the leg than at the height of the cyclist.

What connecting rod length is the ideal for me?

According to these latest studies in biomechanics, the choice of the ideal linked size depends on several body segments that actively inves into the pedaling, such as the height of crop (measured from the perineum to the ground). This reference change is based on the decompensations that each body can have and that are not taken into account when measuring the height. Two cyclists with the same size can have different leg lengths, so they may not have the same recommended connecting rod size.

Connecting rod sizes according to the height of crop

The following table of BIOLASTER It shows how to choose the length of connecting rods depending on how long the legs have. To do this we must measure the length of our leg stretched from the ground to the groin.
Entrepierna height Connecting rod length
Less than 70 cm 165 mm
Between 70 and 74 cm 167.5 mm
Between 74 and 80 cm Enter170 mm
Between 80 and 86 cm 172.5 mm
Between 86 and 99 cm 175 mm
More than 99 cm 177.5 - 180 mm

Choose the connecting rods based on the modality

Mountain Bike cyclist In addition to taking into account the length of your leg to find the perfect size of your connecting rods, you should also consider the special characteristics of the cycling discipline that you usually practice. Although the measures are practically the same in all modalities (road, Mountain Bike, cyclocross or grave) There are certain elements, such as the type of routes, distance or land, which will opt for a rod length or another. On the road, for example, a standard of larger connecting rods, 172 or 175 mm, is being imposed, especially for bicycles more focused on cycling, such as those of Great background geometry. However, in the Aero bicycles, focused on performance, 170 mm rod predominates, which favor the adoption of a more aerodynamic position. In it Mountain biking It also tends to shorten the size of the connecting rods. First because there are biomechanical studies that have demonstrated certain improvements in the accelerations, such as the one made in 2010 William Macdermid (fountain), On the difference of wearing connecting rods, 172.5 mm and 175 mm in tests of Cross country. Secondly, because shorter connecting rods are less likely to hit themselves with the rocks or steps of many trails, thus avoiding that they are damaged or caused.
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