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. Multiple ergonomic features combine to create the level of comfort, posture and stability a rider may require. Due to these multiple factors and the wide variation in anatomy and types of bike, there will never be a “universal saddle” that everyone is comfortable with.
I often say that the easiest factor to consider in saddle selection is saddle width, but like most things that seem simple, the answer is not as straight forward as we would like it to be. 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.
Maximum vs Effective Saddle Width
Saddles generally come in a range of widths, with the width quoted by the manufacturer usually referring to the maximum measurable 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.
Male v Female Saddle Selection
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 (bony points on the bum!). 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.
Effective Saddle Width
For a more sophisticated approach to selecting the ideal saddle width, you need to consider the effective width of the saddle in relation to the width of your pelvis and to your posture on the bike. Effective width is narrower than the maximum width. If you look at the back of a 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 the perineum (your under carriage or front bottom).
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, road bike, time trial bike) each requiring a different riding posture, for any individual the change in cycling posture between bikes may require 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.
Selecting Saddle Width
As mentioned saddle width usually changes with the type of riding you do. The more upright and relaxed the cycling position, the more weight is placed on the ischial tuberosities and the wider (and more padded) your saddle can be. In contrast, the lower and more aggressive your race (or time trial) position, the narrower the saddle needs to be since you bear weight on a narrower part of the pelvic bones (the ischiopubic rami are narrower than the ischial tuberosities). 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 symphysis, 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, labial or penile pain, and genital numbness.
Saddle Shape Affects Effective Saddle Width
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 the 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 compensate in one of a range of ways to establish some postural support from their saddle. This can lead to saddle soreness or back complaints, and even knee complaints.
So the take home messages here for selecting your saddle width are:
1. Get your sit bone width measured accurately. The rubber pads you might sit on in a bike store are, generally speaking, inaccurate.
2. Select the effective saddle width you require. In my experience you are better off and a lot more comfortable with fewer problems when choosing a saddle that is marginally too wide than one that is too narrow. SQlabs are a saddle company that suggest the following “adjustments” to width based on your riding posture (they define pelvic width as the distance measured between the centre of each ischial tuberosity):
a. Time trials with a flat back posture: +0cm
b. Aerodynamic track / road cyclist posture: +1cm
c. Endurance road bike (45° torso angle): +2cm
d. Town / touring bike (not quite upright): +3cm
e. Totally upright: +4cm
3. Measure the effective width of any saddle you are considering and select one that matches the anatomical width you require with the above adjustments taken into consideration (remember that effective width is less than maximum width).
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.