There are quite a few considerations when it comes to choosing a perfect saddle. The perfect saddle is the saddle that you don’t even feel or notice because it’s so comfortable. It’s very difficult to examine every feature that goes into saddle design separately from all other aspects, since each feature interacts with the others to create the level of comfort, posture, stability and cornering support a rider may require. Due to this, the wide variation in rider’s anatomy and the many different styles of bike, there will never be a “universal saddle” that everyone is comfortable with.
I used to say that the easiest factor to consider in saddle selection was saddle width, but like most things that seem simple the answer is rarely as obvious and straight forward as you would like to think it is. Currently I encourage cyclists to seek out a saddle based on its “effective” or “usable” width, which can be very different to simply measuring the maximum width of the saddle.
Saddles generally come in a range of widths, with the width quoted by the manufacturer usually referring to the maximum measureable width of the saddle. In this context a “narrow” width could be considered as 130-140mm, a “medium” width 140-150mm, and a “wide” saddle being 150-170mm.
There is a gender difference in saddle selection based on width. One of the first things you learn in anatomy at university is how to tell the difference between a male and female pelvis. There are well recognised differences with the female pelvis needing to accommodate child-birth, so the average female pelvis is a little wider than the average male pelvis. Anatomical studies suggest that this difference is in the order of 18mm (on average) at the ischial tuberosities. As a result women will tend to use medium to wide saddles and men narrow to medium. Of course there are exceptions, but the point of selecting the appropriate saddle width is that it will rule out about 2/3 of the available saddles on the market from your list of possibilities.
For a more sophisticated approach to selecting the ideal saddle width, you need to consider the effective width of the saddle. Effective width is narrower than the maximum width. If you look at the back of the saddle, the outer edges start to fall away. I define the effective width as the width at which the edges drop by 1cm on each side (see image below). This is measured at the point on the saddle where the cyclists’ ischial tuberosities sit. If the saddle is too narrow it will create pressure exactly where you don’t want it: the soft tissues of your perineum.
How to measure effective width
Maximum width measurement
Effective width measurement
In theory the effective saddle width should match the width of that part of the bony pelvis you are weight bearing on. The weight bearing part of the pelvis varies according to your spinal / pelvic posture on the bike (as we discussed in the first post about saddle selection). Given that there are different types of bikes (eg mountain bike, time trial bike, road bike) that each requires a different riding posture, for any individual rider the change in cycling posture between bikes requires a change in the effective width of the saddle . So it makes sense to have different saddles for the different types of bikes you may own.
So back to considering the type of saddle and the type of riding you do: the lower and more aggressive your race position, the narrower the saddle needs to be. The more upright and relaxed the position, the more weight is placed on the ischial tuberosities and the wider (and more padded) your saddle can be. The reasoning behind this concept is that by tilting the pelvis forwards and riding in a low aggressive racing position (or time trial position) you place more weight forwards on the saddle where the width of the ischiopubic rami are narrower than the ischial tuberosities. Conversely the more upright the rider, which occurs with recreational and touring styles of riding, the more support needed under the ischial tuberosities which are the widest part of the inferior aspect of the pelvis and in this posture will bear almost all of the weight. See the images of cyclists below and the pelvis above to better understand the complexities of pelvic anatomy and its relationship to saddle width and cycling posture.
Remember it’s the ischial tuberosities you sit on in your chair that are designed to take your weight. The soft tissues of the perineum, especially higher on the rami towards the pubic symphasis, are sensitive and not designed to sit on for either male or female cyclists. Excess weight or pressure in the pubic region is a cause of erectile dysfunction or labial pain.
Saddle shape has a significant impact on effective saddle width. Consider the images below of three very different types of saddle: a Selle SMP Stratos (in green); a Fizik Arione Donna (black and white) and a SQ Labs Ergowave 611 14cm saddle (black). Note how the very rounded rear profile of the Sella SMP results in a very narrow effective width, which is in contrast to the very flat profile of the SQLabs saddle, which results in effective width being almost as wide as maximum width. This concept explains why saddles which have the same maximum width (but different effective widths) are not equally comfortable nor equally suitable for a given individual.
Consider what might happen if the rider has a saddle whose effective width is too narrow for the riders’ pelvis: the cyclist would have to rock the pelvis side to side excessively in order to keep both ischial tuberosities in contact during the downstroke for each leg when pedalling. When the effective width is too narrow, excessive rocking doesn’t always happen in the real world; in some cases the cyclist will twist their pelvis and spine to get one sit bone firmly supported whilst the other one relies on some unusual (and subconscious) tensing of buttock and pelvic floor musculature to achieve a level of pseudo-stability to minimise rocking motion. In other words, if the effective width is too narrow compared to the cyclists’ bony anatomy then they compensate, often by trying to get one bone on the saddle firmly. If you can only feel one of these bones when you’re pedalling then this might be happening to you. It can lead to saddle soreness or back complaints, and even knee complaints over time as twisting the pelvis usually causes the knees to twist in their alignment (for example one will twist inwards and the other outwards when cycling).
If in doubt consult a Physiotherapist who works with cyclists and has the ability to measure anatomical landmarks and understands the impact on your preferred mode of cycling.
Read our next blog for more tips to help you select a saddle shape to suit your needs.