How to get the right stem length on your bike

Stem length is a key parameter in the biomechanical adjustment of the cyclist on his road bike, as well as having a great influence on bike handling. Choosing the right size will depend not only on our physique but also on the riding style and physical abilities of the cyclist.

How stem length affects your position on the bike

Often, stem length seems like an immovable measure when we acquire a bike. It comes with a length determined by the manufacturer for that size decided based on statistics and biomechanical studies data that say it is what best suits the majority. However, we all know that no two cyclists are the same and what may work perfectly for one may not necessarily work for another.

The stem length serves to achieve the appropriate effective reach for the cyclist, but what figure is this?. As with everything related to biomechanics, there is no single answer. It depends. In general terms, a cyclist properly positioned on his bike should have the weight distributed between both bike axes, as centered as possible.

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Some biomechanics seek this center of gravity by ensuring that the cyclist's scapula base is over the pedal axis. However, this is valid when choosing the size that is initially appropriate for us. But, on many occasions, whether because the cyclist has long legs, short legs, long arms, in other words, they deviate from the morphologically normative size that would theoretically correspond to us is not the one we have to use, which forces us to adapt the stem length to both fit on the bike and easily reach the handlebars.

It is also very common among competitive cyclists to opt for a size smaller than the one that corresponds to them in order to achieve a stiffer, more compact, and agile bike, as well as sizes with a lower stem that allows them to lower the position. This means they have to resort to very long stems that always catch the attention of novices.

As we always recommend, rather than using the trial and error method, the way to find the correct stem length that corresponds to us is to visit a biomechanic who assesses our morphology, analyzes our pedaling, and determines the best position based on our abilities and the cycling practice we do. Obviously, the position needed by a middle-aged cyclist with limited flexibility is not the same as that needed by a perfectly trained competitor seeking maximum efficiency.

Aside from the constraints regarding the cyclist's position, stem length also influences the behavior of the bike, simply because a longer stem makes us exert more leverage on the steering, and although we require less force to move the steering, we have to make wider movements to achieve a certain displacement and, conversely, we achieve a more direct behavior.

Of course, it also affects the balance of weights between both axes, in fact, one of the reasons why professionals opt for long stems is to shift weight to the front axle so that the grip of the front wheel is maximized, gaining safety in the trajectory when descending at high speed.

As you can see, a seemingly simple component has a tremendous influence on the behavior and position on the bike with the added problem that the trial and error method until finding the right one is no longer viable with current bikes that use expensive integrated handlebars and guide the cables inside this component. Therefore, we insist that you trust a qualified biomechanic to get it right the first time with what suits you best.