The understand better the principals behind the Cyclefit measuring system below a short explanation of how the adjustments for both length and height have been developed
Correct Saddle Position
Cycling is not very efficient when looking to maximize the use of the leg muscles. Only during part of the pedal rotation can the hip and knee joint deliver force while stretching. Despite that, one can still achieve the highest efficiency during pedal rotation. To achieve this, however, the contracting and stretching of the muscles have to be within certain limits. A muscle creates force by contracting, and therefore can be compared to a pull spring. When the ends of the spring are close to each other, little to no force is created. When pulling the ends further from each other, the force increases. When the spring or muscle is overstretched, then the force will be lost. In order to maintain a smooth and supple pedal pace, the saddle needs to be adjusted so that the knee is not fully stretched or extended. Not only do the leg muscles function inefficiently and insufficiently when the saddle is positioned too high, also the pelvis will rock from side to side, which transfers to movement in the spinal column. Eventually, this can cause back problems. The saddle cannot be positioned too low, so that the knee bends still too much at the bottom of the pedal stroke. In this position, the quadriceps cannot develop enough force, as the muscle is being overstretched. The advised saddle height by CycleFit is not only for optimum force, but also prevents the muscles from being overstressed. From several tests, it has been shown that the incorrect saddle height will lead to an increased use of oxygen compared to a CycleFit set optimal height. This means that more energy is being used for the same effort. When riding with an incorrect saddle height, one is already starting from behind from the start.
Characteristic for the CycleFit advised position is the stretched position. This position is suitable for mid and long distances and unburdens the wrist, neck, and spinal column. Many have neck problems due to incorrect saddle position complaints that can be directly related to too short bikes. CycleFit advises a long forward stretched position. Stretching the back will unburden the neck and lower back. In addition, a stretched back leads to the enlargement of the thorax. This will lead to a increase of oxygen intake. Also, the more forward overturned position of the pelvis creates more stability. Finally, this position is more aerodynamic.
A short position can lead to back problems because of the terse position of the spinal column. This position caused a lot of stress on the lower part of the back. Besides that, the neck has to make a sharper angle in order to look ahead, which can cause cramps. The short position, from the pelvis, up the spinal cord, to the head causes lots of stress. The cyclist becomes cramped. The oxygen supply is limited in this position because the thorax is being compressed.
Although the Cyclefit programme incorporates a large number of parameters there are several parameters that are not (yet) included. The following points should be taken into consideration.
Leg length difference
Some cyclists have a leg length difference. Cyclefit does not offer a standard correction for this. In this case, a clear distinction should be made between a ‘real’ length difference and a length difference that is caused by an incorrect posture. In the case of the latter, the person can often reduce or solve the problem with the help of exercises. In this case it’s not wise to compensate for the length difference because this may force the cyclist into an incorrect position. In the case of a ‘real’ leg length difference, it’s important to know if this concerns the upper or lower leg as this will determine the way in which this will be compensated. If the difference in leg length is in the lower leg, the problem can usually be solved by a plate under the shoe. If the length difference is in the upper leg, the problem can normally be solved by moving the shoe plate forwards or backwards. Please note: if you have a leg length difference of over 10mm, then Cyclefit recommends consulting a sport doctor / physiotherapist first.
Flexibility of the pelvis / lower back
As explained elsewhere, to adopt the correct position the pelvis must be tilted slightly. The posture that Cyclefit advises will offer relief to your back. Even people with back complaints, such as hernia, will be able to adopt this posture. If the cyclist does not have sufficient pelvis flexibility, then we advise positioning the handlebars higher [maat N verkleinen], but not closer.
As illustrated on the previous pages, the frame size is measured as if it were a traditional frame with a horizontal top tube. In practice, this means that this measurement cannot be measured directly on the frame. The measurement is determined by placing the bike on a level surface and using a long level from the centre of the fork head tube, the level is positioned horizontally and the distance between the bracket and level is measured.
Different types of seat posts
The aerodynamics of the frame has become increasingly important. As a result, more and more frames with different shaped seat posts are put on the market. This can pose a challenge when measuring the length of the top tube. This is typically measured from the centre of the fork head tube to the centre of the seat post / saddle pin. However, the Cyclefit system will also work with an accurate measurement of the ‘reach’, the length of the top tube (measured horizontally) from the bracket to the centre of the fork head tube.