* Maximum power application to the pedals
* Road Safety (better control of the bike)
* Easier to achieve aerodynamic position
* Injury prevention
If the saddle is too high it will be difficult to spin the pedals at high cadences, there will be undue pressure on the hamstrings, Achilles tendons, Gluteal muscles and lower back you will also be more likely to get saddle sore from friction as your rear end moves from side to side on the saddle.
If the saddle is set too low there will be undue pressure on the front of the knee as there is more pressure generated between the Patella and Femur by the more acute angle at the knee.
CALCULATING THE SADDLE HEIGHT
There are many suggested methods of determining the optimum saddle height. However they are all only guides and designed to get the rider very close to the optimum height where the height is then very often gradually adjusted until the rider feels it is correct.
A simple method, which many competitive racing cyclists use successfully, is by measuring the inside leg (inseam) to the ground while barefoot and multiplying by 0.885
The saddle height is measured from the centre of the top of the saddle to the centre of the bottom bracket axle,
This measurement should bring you to within one or two centimetres or so of the ideal saddle height, allowing for the type of pedals used, shoe size, thickness of the soles of the shoes flexibility of your thigh muscles etc.
For example, if the rider has large size shoes the saddle might need to be raised, or lowered for smaller size shoes and this can be refined with very slight adjustments over the next few weeks until the ideal height is achieved.
Women have to be careful with this as usually they have smaller shoe sizes and the saddle often has to be lowered to allow for this.
Having adjusted these measurements, there should then be a reasonable bend in the knee when the feet are in the pedals (pedaling position) and the pedal is at the lowest point (the crank in line with the seat tube) with the lower foot horizontal.
Any changes to the saddle height should consist of a max of five millimetres every week or so to allow your muscles to adapt to the changes.
The final adjustments must be closely monitored until the rider feels perfect on the bicycle.
When a final decision has been made on the optimal saddle height and position this should then be a fixed measurement. If you need to change your reach to the handlebars the handlebar stem may need to be adjusted or changed.