How to choose the correct stem length

How to Determine the Right Stem Length for You and Your Bike?

The simplest way to find out which stem length is right for you is to consult professionals in the field who will determine, in simple or more complex ways, the best saddle position for you. Many bike shops, in fact, offer a “bike fitting” service for free with a purchase. Stems are available in various lengths to better suit the needs of the cyclist. Simplifying, if you want a more aggressive and aerodynamic position, a longer stem will give you a more extended position. If, on the other hand, comfort is your main interest, a shorter stem will give you a higher and more relaxed position that won’t strain your back. However, the stem must be considered as part of the overall measurements and position on the bike. In short, it must be considered along with the frame size, saddle height, saddle setback, and the shape and size of the handlebar. That’s why a careful assessment of position should be done by a professional: it’s all a bit more complex than it might seem at first glance to the inexperienced. However, small experiments are allowed and can be quite useful in some cases. Let's see, then, what are the main components that the stem length affects and some small adjustments that will help you, if not to decide, at least to start unraveling the tangle.

Stem Length Affects Handling

Changing the stem length not only impacts comfort but also affects the handling dynamics of the bicycle. A shorter stem, in fact, results in quicker steering, while a longer stem, conversely, leads to slower steering. By adjusting the stem length, you can therefore adapt the handling to your needs. Cyclocross riders, for example, use shorter stems than road cyclists because they need more responsive steering in tight corners.

Correct “Reach”

The stem length alters the actual “reach” measurement to the handlebar. The “reach” measurement, remember, is the horizontal distance between the center of the head tube and the center of the bottom bracket. The stem length doesn’t directly affect this measurement but does so indirectly because it extends the cyclist’s position. So, it’s important to be careful and take this into account. If you've ridden your bicycle for some time, your feelings can be a good initial indicator. Neck, shoulder, or back pain can be a first sign that your position is not correct and that you might need a longer or shorter stem.

Optimal Position

Finding the optimal position is much more difficult than it may seem. However, we can say that a correct position leads to having slightly bent elbows. If the stem is too long, the arm would remain completely extended, which could cause several problems, not just with handling, but also with the back. A good way to check if your saddle position is correct is to sit on the saddle and grab the brake levers with your hands. Looking down, if the front wheel hub is covered by the handlebar, then, generally, the position is correct. If in this position you see the hub in front of the handlebar, it probably means the stem is too short. This is a general method, the best thing, as mentioned earlier, is to consult a professional in the field.

Experiments with Stem Length

Don’t be afraid to experiment, though. Small changes can lead to significant benefits in comfort or aerodynamic performance, depending on what you’re looking for. Try changing the length slightly (start with 10mm?) and take a couple of rides to see if things improve or worsen. However, if you notice that the changes you've made are significant, it probably means you have a wrong-sized frame. The stem is indeed meant to make small adjustments to allow you to achieve the maximum.

Stem Length in Relation to Frame

Most manufacturers fit the stem length in proportion to the size of the bike frame itself. Therefore, smaller-sized bikes will have very short stems; while larger bikes will have longer stems. This tends to standardize things a lot and can lead you a bit off track regarding the correct length of your stem. Generally, the length of stems on road bikes varies between 80mm and 140mm. The most common size is about 100/110mm. However, there are shorter or longer stems for very short or very tall people who find themselves at the extremes of the sizes.

Stem Angle

Another factor to consider is the angle of the stem. Stems with negative angles will lower the handlebar height and are perfect for those looking for a lower and more aerodynamic position. Conversely, positive angles will raise the handlebar, promoting comfort. It depends, in this case too, on everyone’s preferences.

Do Not Copy the Professionals!

A general golden rule, do not copy the professionals! Many amateurs choose their stem length simply by observing and copying the choices of professionals. This is dangerous. A professional cyclist has a bike assembled to perform at its best, and they often assume a very extended and aerodynamic position. To maintain that position, however, they work very hard during the winter. Most of us are not able to maintain those positions.