Читать книгу The Bonsai Handbook - Adam Dickson - Страница 24

Once you have chosen the right frame and you’ve properly fitted the shoe cleats it’s time to look at the height of the saddle as it is the most important aspect of positioning on your bike. The saddle height affects the muscle activity of your legs. If the saddle is placed too high you run the risk of over-stretching your muscles and when the saddle is placed too low the pressure on your quadriceps might become disproportionately high. The correct saddle height enables your muscles to work optimally in the longitudinal reach and you will be able to maximize your power. You measure the saddle height from the heart of the bottom bracket to the upper part of the saddle in line with the seat post. To calculate your saddle height you have to know your inseam length. Your inseam length is measured as follows:

1. Stand straight up on your bare feet with your heels, back and head against a wall.

2. Position the inside of your feet approximately 15 to 20 centimetres (six to eight inches) apart.

3. Put a tube (eg a plastic bottle) with a diameter of three and a half to seven and a half centimetres (about one and a half to three inches) against your crotch, exerting the same pressure as your saddle would.

4. The edge of the tube should be horizontal and flush with the wall.

5. Ask a friend to draw a small line on the wall where the tube reaches its highest point.

The formula to measure the optimal saddle height = inseam length x 0.88.

Note: this saddle height calculation is based on Look Keo pedals and other pedals have a different stack height (check with manufacturers). This is the distance from the top of the cleat to the centre of the pedal axle. The closer your foot is positioned to the axle the more efficiently power is transmitted to your bike. When you change pedals your foot might be closer to the axle. The lower the stack height, the lower the saddle height. As an example, 87.5 (inseam length) x 0.88 = 77cm saddle height with Look Keo pedals (stack height 17.1mm). When you then switch to, for example, Shimano SPD SL pedals (stack height 13.7mm) you should decrease your saddle height according to the difference in stack height between the two pedals. This is 17.1mm - 13.7mm = 3.4mm, giving a new saddle height of 76.6cm.

If you need to radically change your saddle height then make the adjustments gradually so your body has time to adapt! If you are currently used to a saddle height that is off by a lot, then adjust the saddle by 2 millimetres (a fraction of an inch) per week.