The most important parameter that it makes sense to pay attention to when choosing this vehicle is the size of bicycles (i.e. the size of the frame). Material, model and appearance are not so important as comfort and a suitable size of an iron horse. Only in this case it will be convenient to ride.
Size History
To choose the optimal bike size, a number of parameters need to be considered. Everything used to be much simpler. In Soviet times, there were only road and road bikes. The frame had standard geometry, and the upper tube was always located strictly horizontally. Therefore, choosing the optimal height was easy. If necessary, it was always possible to additionally adjust the position of the steering wheel and saddle. The selection was carried out along a horizontal pipe, because it was the only parameter that could not be adjusted. In other words, only the size of the bicycle frame was used as the most important parameter. Everything else was customized for growth.
Currently, the range of bicycles has expanded. Frames of various geometries have appeared, for many types of bicycles the seatpost is located diagonally. Very often you have to deal with an unregulated steering wheel, etc. All this complicates the choice of a suitable model. And besides this, manufacturers consider the height differently and use different length systems. Now not only the size of the bicycle frame is used, but also the size of the wheel, the distance between the steering wheel and the seat and other parameters. However, seatpost height is still one of the leading factors. If you jump from a bike that is too high, you can hit with your groin and even cause yourself damage. If the frame is too low, skating becomes uncomfortable, you have to raise your legs above your head, as a result, the load is distributed incorrectly, which is also harmful to health.
Notation used in formulas
The calculation formulas used are pretty rough. In addition, there are a great many of them. They can vary not only from model to model (mountain, highway, sports), but also from manufacturer to manufacturer. However, the formulas to a greater extent take into account the characteristics of the bicycle, and not a person. And yet, in stores, they often resort to the calculation method of selection.
On a bicycle, parts are marked as follows:
- C is the seatpost length.
- SS is the horizontal distance between the saddle and the steering wheel.
- SIZE (CC) (center of pedal carriage - middle of upper pipe).
- SIZE * (CT) (center of carriage - top edge of seatpost). This is the so-called. frame growth.
From a person, only one parameter is required: the height of the perineum - VP. It is measured on the inside of the leg, from the heel to the groin. Also, in some cases, human growth is used.
How to find the right bike size: formula
When selecting, it is necessary to clarify the method for measuring frame growth : CC (center-center) or CT (center-top). The formulas in this case will be different.
The size of a road bike is calculated using the following formulas:
- SIZE (CC) = 0.65 x VP.
- SIZE * (-) = 0.67 x VP.
The size of a mountain bike is calculated differently:
- SIZE * (-) = 0.67 x VP - 10 cm.
- SIZE (CC) = 0.67 x VP - 12 cm.
For mountain bikes, the distance from the steering wheel to the saddle is of paramount importance, since the former is often impossible to regulate.
Trying Method
To do this, stand out of the blue, holding the seatpost between your legs. It is necessary to measure the distance between the groin and the frame. For a road bike, this parameter is optimal at 25–75 mm, and for a mountain bike, 100–200 mm, in some cases up to 5 cm.
table of correspondence
However, not all stores have the opportunity to try on a bike. Therefore, they often resort to various correspondence tables. For different models, the parameters may vary. Usually bicycle sizes are indicated in inches (digits), less often in centimeters. A letter designation may also be used. But the most generalized experience would look like this:
Bicycle size, compliance tableFrame size in inches
| Letter marking | Human height in cm |
13-14 | XS | Up to 150 |
14-16 | S | 150-160 |
16-18 | M | 160-170 |
18-20 | L | 170-180 |
20-22 | XL | 180-190 |
22-24 | XXL | 185 and more |
Of course, the proportions are averaged. Accuracy up to a millimeter is not to be expected. However, it will help to navigate approximately in the sea of goods. Knowing at least an approximate ratio of body length and frame height will significantly narrow your search.
The choice of the size of the bike depending on the type of riding
The height of the frame will differ not only from the purpose of the bike, but also from the riding style, the planned operating conditions. And this convenience of this or that type of riding is determined by the size of the bicycle. The table will help to make a choice. So, for leisurely city walks, you can buy a two-wheeled friend along the upper border. For example, with a growth of 160 cm, an 18-inch bike will be quite comfortable for urban conditions. And for aggressive riding, mountain trails and other complex elements, it is better to use a more compact iron horse with a frame of 16 inches or less.
Other sizes: wheel size
Often manufacturers indicate the diameter of the wheel. Depending on this value, all bicycles can be divided into children and adults. The first category includes wheels with a diameter of 12 to 24 inches. 20-24 inches are already considered teenage. By the way, adults of low stature may well ride on such models, since the frame, distance to the steering wheel and all other parameters are proportionally increased for an iron horse with a large wheel.
26 and 29 inches are common sizes for adult mountain bikes. The number 28 is often found on models designed for urban skating.
How to determine the optimum height of a bicycle saddle
Perhaps this is the only parameter that is adjustable. Rarely there are models where the saddle height remains unchanged and depends on the size of bicycles. Optimum location can only be determined empirically. Sitting in the saddle you need to pedal. At the lower point, the leg should not straighten completely, but remain slightly bent (no more than 160 degrees). At the upper point, the thigh can be horizontal, parallel to the ground, and slightly inclined downward. The knee should not rise above the pelvis. This suggests that the saddle is too low.
Steering wheel height
When you have decided on the saddle, go to the steering wheel, because their location is interconnected. To determine the height of this part of the bicycle, the chosen riding method will play a primary role.
For racing tracks and high-speed driving, the steering wheel is installed below the saddle by about 10 cm. Depending on the individual characteristics, +3 cm.
For aggressive driving and the same tourism, when it is supposed to overcome various obstacles, descents and ascents, the steering wheel should be 2-6 cm below the saddle. For older people, it is permissible to set them at the same level.
For walks around the city, the highway and riding on flat tracks, the steering wheel can be located saddles above or at the same level.
Saddle width
Another parameter that cyclists traditionally pay little attention to. Although it has little to do with the issue of bicycle sizes, it is completely in vain ignored, since a lot depends on a comfortable seat. If it is too narrow, then abrasions can occur, and the buttocks and lower back can begin to hurt. An improper saddle can cause various health problems. If it is too wide, then pedaling will be inconvenient, because the thigh will not be able to move freely. The sciatic tubercles should not fall on the slopes, but on the still flat edges of the saddle. Then it will not cause discomfort, get between the buttocks, rub, etc.
You can find out at what distance sciatic tubercles are from each other as follows: you need to sit on even sand, and then measure the distance between the deepest depressions. This will be the optimal width. It should be remembered that women have more pelvis than men. Therefore, bicycles for the fair sex differ not only in color, but also in the width of the saddle.
For a purchase, it is better to go to a specialty store. Here, experienced sellers will tell you how to choose the size of a bicycle, taking into account all the characteristics of the person and the intended riding style.