Finding the Right Size Bike for You – How to do it right?
If you have already decided what type of bike is suitable for your needs, then you should move on to the next important stage – choosing a bike for a person’s height.
In this article we will talk about the features of choosing the right frame size for an adult. Choosing a bike for a child has its own nuances, so we recommend reading our article How to choose a bike for a child.
What are the risks of riding a bike that is not your size?
First of all, it is inconvenient. Here you can safely draw an analogy with clothes or shoes – discomfort will make you stop wearing or putting on this or that thing because of inconvenience or awkward appearance.
It is the same with a bicycle. An uncomfortable fit, which results in an incorrect distribution of your body weight on the bike’s controls and seat, contributes to pain in the neck, lower back and wrists, which can completely discourage you from cycling.
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Secondly, it reduces your productivity and efficiency. The frames of modern bicycles are designed taking into account the anatomical features of the body in certain growth intervals.
The length and height of the frame are selected in such a way as to provide your torso and legs with the optimal position for the rational use of your strength and capabilities. Violation of one of the parameters leads to the wrong position of joints and muscles, in which you will not be able to make the most of your efforts.
Thirdly – more harm than good. Riding a bike that is not your size you risk to spoil your posture and disrupt the knee joints, or even disable them. The wrong position of your body will make you bend more or hunch over, which will eventually lead to fixation of the spine in this position even off the bike.
As for the knee joints, when the legs are not fully straightened, friction occurs in other areas of the necks of the knee bones, which are not designed for such loads and movements. Over time, due to rubbing, inflammation may form or other more serious diseases may appear.
What does frame size mean and where can I find it?
All bicycles have a frame size designation, which is applied as a sticker or is part of the bike design. Most often, this marking is on the seat tube and can use a variety of numeric or alphabetic combinations. Numerical designations may use a measurement system in inches or centimeters.
Alphabetic in the form of symbols of the English alphabet and in this case it is possible to draw an analogy with the sizes on clothes (S, M, L, XL, etc.). Each designation is able to cover a certain period of human growth due to the adjustable seat height. The seat tube of the frame is welded at a certain angle so that by raising the seat post not only the seat height but also the distance from the handlebars changes.
Why can’t one frame size be made, and the parameters of seat height and distance from the seat to the handlebars set by the seat tube? For such purposes, manufacturers would have to significantly increase the wall thickness of both the frame tubes and the seat tube, which would significantly weigh down the entire structure.This would also negatively affect the running qualities of the bike, because the rigidity of the frame is reduced. No, this practice is commonly used, especially in folding bikes. That is why they are so small in size and have a weight approximately equal to a full-fledged bike. Well, as you understand, you can’t go fast on a folding bike and you can’t make much effort either.
Calculate Your Bike Size
There are two main methods for calculating the size of the bicycle frame that you need. The first one is based on your height and inseam (the distance from the crotch to the floor).
The second method uses your height as a parameter and provides an opportunity to take into account different proportions of leg length to torso. In general, according to this method, if you have long legs in relation to your height or a short trunk, then you should choose a larger frame size. And vice versa – when the trunk is longer than the legs or the legs are very short – it is worth taking a smaller frame size.
Height and inseam
So, having determined which of the two options is more convenient for you, calculate the required size by one of the following formula:
You need to take into account your height and inseam. The frame size is calculated using the formula: frame size = inseam (cm) x 0,685 + 10. If you have an inseam of 80 cm, then your bike size will be 58 cm.
The table below will help you more accurately determine the size of the bicycle frame, based on both your height and inseam:
In order to find out your inseam, you need to take a book and, putting it against the wall, put your heel on it. The distance from the crotch to the floor is your inseam. If you don’t have a book at hand or can’t do it yourself for some reason, ask someone for help.
You can also measure your inseam using a special device – a stadiometer. You can find such an instrument in any sports store. Just stand up against it and read the number that will indicate your height. To find the inseam, you need to subtract about 2.5 cm from this figure.
For example, if a person’s height is 185 cm, then his inseam will be approximately 182.5 cm (185-2.5 = 182.5). Now that you know your inseam, you can easily calculate the size of the bike frame by the formula given above.
It should be noted that this method of calculating the size of the bicycle frame is suitable for people with an average build and proportions. If you have very long legs or a short torso, it is better to use the second method for calculating the size, which takes into account not only your height but also your proportions.
The ratio of leg length to torso length
The second method is based on your proportions – the ratio of leg length to torso length. If you have long legs in relation to your height or a short trunk, then you should choose a larger frame size. And vice versa – when the trunk is longer than the legs or the legs are very short – it is worth taking a smaller frame size.
According to this method, the frame size should be: 54-56 cm – if your height is 152-160 cm; 56-58 cm – if your height is 160-168 cm; 58-60 cm – if your height is 168-176 cm; 60-62 cm – if your height is 176-184 cm; 62-64 cm – if your height is 184-192 cm.
Let’s say you have an average build and your height is 172 cm. In this case, according to the first method, you need to take a bike with a 58 cm frame.
But if you have long legs or a short trunk, it is better to choose a larger frame size – 60 cm. And if your proportions are such that you have a long trunk or short legs, then it is worth taking a smaller size – for example, 56 cm.
The main thing is that when choosing a frame size, you should feel comfortable on the bike. The saddle should be at such a level that when pedaling, your leg will be almost straightened in the knee. If your knees are bent too much – it means that the frame is small for you, you need to choose a larger one. If the leg is fully extended on the pedal – the frame is too large and you need to choose a smaller one.
Of course, it is not always possible to find the perfect size, but it is still worth trying to do it as accurately as possible so that you are comfortable cycling.
And one more thing – if you can’t choose between two sizes, it’s better to take the smaller one. Because if the frame is too large, you will always be able to lower the seat and handlebars. But if the frame turns out to be small, then you will not be able to significantly increase its size. Therefore, when in doubt, it is better to give preference to a smaller size.
Bottom Line
It’s quite simple – just find out your exact height. You will be surprised, but most people cannot answer this question and immediately run to look for a tape measure. Knowing the length of your body from the heels to the top of your head, as well as the inner length of your legs – you can choose the right bike with the frame of the size you need, just look at the plate below.