Saddle position
Saddle position is the foundation of a good bike fit. Finding an appropriate handlebar height and reach cannot be done well if a proper saddle position is not established first.
There are 3 aspects of saddle position - height, fore/aft or setback, and tilt. They are all inter-related, and often adjusting one aspect will require reviewing another.
The other consideration is the actual saddle itself. The saddle’s characteristics such as width, shape, firmness, and cut out will influence whether you are comfortable and efficient when pedalling.
Saddle height
There are a number of basic methods and calculations that can be used as a starting point to set saddle height, most based on a relationship between saddle height and lower limb length (inseam), or a reference range for knee joint flexion. Of these methods, it is preferable to use one that sets saddle height according to knee angle rather than a formula, although there is no absolute consensus on what this angle should be. Research suggests that a dynamic angle of around 30-40deg is optimal. However, none of these methods take into account individual characteristics such as flexibility, pedalling style or limb proportions.
Common issues resulting from an inappropriate saddle height include knee pain, saddle discomfort (pressure, numbness, sores), hip pain/impingement, hamstrings tendinopathy, achilles issues, back pain, neck pain, and hand and wrist pain/numbness. However, you don’t necessarily need to have pain or injury for then saddle height not to be optimal! An inappropriate saddle height can also result in a reduced power and efficiency.
Saddle fore/aft
Saddle fore/aft (or set back), is the horizontal distance between the centre of the bottom bracket and the front of the saddle, and is the main adjustment affecting weight distribution on the bike and how much upper body work is needed to stabilise the body under load.
Saddle fore-aft should aim to set the rider’s centre of gravity in the position on the bike that does not cause undue discomfort (especially on the upper body), is not too fatiguing, is functionally stable and allows good weight distribution between front and rear wheels. It also should promote an even spread of load through the muscle groups and allow the hip to function within it’s anatomical range.
Various starting points can be used, such as the Knee over pedal spindle (KOPS) or Balance Test methods, or even the rider’s current position. Small adjustments can be made from there to achieve an ideal position.
KOPS, or Knee Over Pedal Spindle, is a traditional way that some bike fitters have used to set saddle setback. According to KOPS, a vertical line from the tibial tubecle should intersect the centre of the pedal spindle when the crank arm is at 90deg on the downstroke. However, some argue that the rider’s centre of gravity is a more important factor in setting saddle setback.
Saddle fore/aft has an influence on muscle recruitment - how far forward or back the saddle is placed will change the relative contribution of the quads, hamstrings and gluts. It also influences hip angle - a forward position will open the hip angle (less hip flexion) and further back will result in a more closed the hip angle.
Individual characteristics need to be considered when determining an ideal saddle setback, including range of motion (especially the hip), anatomical variations (eg. long femurs and large upper body mass will require more set back) and core or functional stability.
Saddle tilt
Settling an appropriate saddle angle is important for comfort and efficiency on the bike.
There are very few occasions where a saddle should be tilted nose up, in fact almost never. A saddle tilted nose up will encourage posterior pelvic rotation as the nose stops the pelvis from rolling forward. This will result in increased spinal flexion and possibly lower back pain, and over-reaching for the handlebars, resulting in neck and shoulder pain. Glutes can get inhibited or hard to recruit. It can also cause perineal pain and numbness due to increased pressure at the front.
An inappropriately tilted down saddle will create instability as you tend to slide forward on it, and also result in you sitting on the narrow part of the saddle providing less support for your pelvis and creating pressure through your perineum. It can increase tension through your quads (and therefore knees) as you brace yourself from sliding forward, and you also end up increasing weight going through your upper limbs, causing hand or wrist pain.
Many people tilt their saddles down excessively in an attempt to relieve perineal pressure or numbness. If this is the case you probably need a different saddle that is more suitable for you, often one that is wider or has a (larger) cut out.
How much a saddle should be tilted down not only depends on the characteristics of the individual rider (e.g. type of riding, flexibility, core strength, personal preference, etc.) but also the type of saddle they have. A saddle with a wave-shape in the horizontal plane - or kick up at the back - can be tilted down far more than a completely flat saddle.
The aim is to find the comfortable sweet spot, where the pelvis is stable and supported, you have sufficient pelvic rotation forward, perineum pressure is minimised, and the hands are not overloaded.
How do I know that my saddle is in an optimal position?
A stable pelvis with sit bones supported, without excessive tilting of the pelvis from side to side
A stable foot - there should not be excessive toe down or heel down.
A smooth pedal stroke - a “dead spot” or a feeling of losing contact at the bottom of the pedal stroke may mean the saddle is too high or too far back.
Not continually moving on saddle - we often move forward or back on the saddle to find ideal knee extension, or where the saddle is most comfortable
Balanced recruitment of muscles with an even load and tension through the major muscle groups
Minimal discomfort, especially the knees, hands, lower back, neck, or at the saddle itself.
Good weight distribution between the 3 contact points (feet, hands, saddle) as well as the front and back wheels (for stable handling)