Bike Sizes

Buying bicycles is easy but not in the case of buying the correct bike size that fits you. Bicycle sizes are measured by the length of the seat tube. This measurement is taken from the center of the top tube to the center of the bottom bracket of the bike frame. Tips on buying the correct kids’ bicycles sizes is covered in another article of this site.

Road Bike Sizing

In the case of road bike sizes, they come in metric measurements of 54cm, 56cm, and 58cm, so on and forth with intervals of 2cm each size.

Sometimes the dimensions on road bikes can also be measured by the horizontal line that runs from the top of the center of the head tube to the center of the seat tube. The usual range of the length is from 53cm (21 inches) to 58cm (23 inches).

It is important to know how tall the cyclist is in order to get a bicycle that is of the right size. Below is a bike sizing chart as reference:

Height of Cyclist/ Rider (cm)	Length of Top Tube (cm)	Height of Cyclist/ Rider(feet, inches)	Length of Top Tube (feet, inches)
160 – 170	53 – 54	5 ft 3 in – 5 ft 7 in	21 inches
172 – 180	54 – 56	5 ft 8 in – 5 ft 11 in	21 – 22 inches
183 – 193	56 – 58	6 ft – 6 ft 4 in	22 – 23 inches

Besides taking the rider’s height as a reference, there are also other factors to note when it comes to bicycle sizes. The frame’s top tube should also be in proportion to the handlebar stem so that the whole bike is of a well-balanced set up. Shorter stems give quicker responses in controlling while longer stems allow more flexibility in maneuvering. An ideally set up bike should allow rider to have his back inclined at 45 degrees and with arms slightly bent when reaching out to grip on the handle bars.

The length of a bicycle’s head tube will also affect the saddle seat position and pedaling position. While the saddle position can be adjusted forward or back in accommodating the distance to reach the handlebars, the position of the pedals is one thing to take note of as improper pedaling postures can lead to knee and leg problems.

For mountain bike sizes, the seat tube lengths are still sizing factors for some hardtail models, however they are measured in inches instead of centimeters (imperial measurements). Generally, mountain bike frames are smaller than road bike frames.

The following are few tips that can guide you in determining the bike sizing and fit:

Reach

Shorter top tubes would mean sitting in a more upright position and longer top tubes will result in a more inclined riding position. An ideal reach would be one that allows the rider’s torso to lean slightly forward without having to lean too far forward to reach the handlebars. To adjust the reach, the stem can be changed to a shorter or longer length or adjusted to a higher or lower position. Additionally, the saddle can also be adjusted backwards or forward to accommodate the reach.

Standover

This is a very simple thing to do in measuring your body frame against the bike frame. Stand over the bike frame and make sure the top tube is at least 2 to 3 inches below the height of your groin. The saddle height can be fine-tuned by adjusting the seat tube length.

Position

The ideal position for most cyclists will be a 45 degree inclination to the back when the cyclist’s hands are on the brake hoods of the handle. This is especially true for leisure cyclists. For racers, the inclination can be lower. For mountain bikers, they are usually casual cyclists and comfort would be most important to them, thus the position of riding should be one that is upright.

Saddle Height

Mountain bikers mostly prefer to have lower saddle heights as this gives them extra clearance and greater mobility. Every individual has a unique body built and different lengths of legs, thus the experience of bike fitting is not the same for everyone. With the help of pedal cleats and wedges, pedaling motions and feet pronation of a cyclist can be altered to give optimized comfort.