Choosing the correct length cranks

autorRotor Bike Components
fecha7th October 2020

Have you ever stopped to think about the length of cranks you use? Maybe it is something that you have looked into to get the maximum performance from your pedal stroke, or maybe you have never thought about it. At ROTOR we are specialists in offering our cranks in a multitude of lengths. You only have to choose the one that best suits your needs. We explain the details of the importance of the correct length of cranks.

In order to get the most out of our training, we must optimize all the elements that intervene in the pedaling cycle. The cranks are one of the main parts of each pedal stroke and that is why at ROTOR we are one of the brands that has the most crank lengths on the market. If you want to adapt your pedaling style, your cadence and your power, you must bear in mind that a crank length suitable for your morphology and technique can help you feel more comfortable and pedal more efficiently.

Although the usual crank lengths for most users are between 165 and 175mm (in 5mm or 2.5mm intervals), at ROTOR we have models like the Aldhu for road, which are available in up to seven sizes (150, 155, 160, 165, 170, 172.5 and 175mm). Although there are not many studies that confirm that one crank length or another can vary the power generated in the pedaling cycle, shorter cranks can help you in certain circumstances.

Choosing a shorter crank can help you achieve a little more comfort when riding and reduce the stresses that occur in the knee and hip due to less stress suffered by both joints. Also, with shorter cranks, you can improve the quality of your pedal stroke, as effectively the pedal stroke circumference has a smaller diameter, which affects the ergonomics of your hips and knees during the pedaling cycle. The leverage applied is less and thus less stress on the joints. Also, from an aerodynamic point of view, switching to a shorter crank makes the position of your back drop slightly and improves your aerodynamic penetration on the bike.

It is very important that you keep in mind that the height of a rider, as well as the height of the saddle to the bottom bracket, are not decisive for the crank length to be very different. You can see riders with a high 860mm saddle height with a 170mm or 172.5mm crank. Similarly, a low saddle height as with shorter riders, of, for example 650mm, makes them use 165mm cranks. In other words, with a notable difference in saddle height, the crank length changes by only 5 or 7.5mm. This is a key indication why there is now a clear trend for shorter cranks even on plus size riders.

The best way to know which crank length is the most appropriate for your height and your pedaling style and position on the bike is through a biomechanical study. There are tables in which they recommend one crank size or another, depending on your height, but it is only a recommendation. If you are two meters tall, this does not mean you need to run a 200mm crank length nor for being 1.50m means you need to use a 120mm crank. Height is a factor to take into account, but not the only one in choosing the right length.

By carrying out a biomechanics study, you will be able to understand what crank length you need, taking into account the work you do with your ankle, knee and hip joints, which are those that use the large muscle groups of the leg when pedaling.

Normally what we do at ROTOR, on road models like the Aldhu or Vegast, we have more crank lengths available, so you can find the exact measurement that suits your pedaling style. On the other hand, on mountain bikes the measurements are more limited since, in addition to the pedaling cycle, other factors come into play, such as ground clearance, and most of our models are available in lengths of 165, 170 and 175mm. Including models with an integrated powermeter such as the 2INpower.

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