The perineal nerve arises from the pudendal nerve to supply the perineal area and the sexual organs. The pudendal artery also forms the perineal artery that supplies blood to the same area. Both these structures can be compressed and compromised with prolonged, direct pressure from a poorly fitted saddle.
Most cyclists don’t realise that saddles actually come in a range of sizes. I am often explaining to patients that saddles are like shoes – the most important thing is they fit, the gimmicks are secondary. Saddles commonly range from 130mm to 170mm and the essential measurement to determine which one is appropriate is your sit bone width.
How Wide Are My Sit Bones?
When I measure a clients sit bones and we determine they need a wider saddle, their first thought is – “oh, so I have a big butt”. Sit Bone width is the boney architecture of the pelvis, it bears no correlation with pelvic width or mass. I see large clients with narrow sit bones and skinny clients with wide sit bones, the important point is that they are weight bearing on the saddle. A poorly fitting seat that is too narrow will sit inside the sit bones. the edges of the seat rub up against the inside of the sit bones and cause painful saddle sores. The prolonged perineal pressure leads to perineal artery and nerve compression which results in numbness to perineal area and possible sexual dysfunction and urinary issues.
What Can I Expect With The Correct Width Saddle?
Well firstly comfort. You are now sitting on the widest part of the saddle, through your boney architecture. This enables the rider to connect to the saddle as a reference point and apply the greatest amount of power through the legs. We have all ridden behind cyclists that rock around their saddle as if they are sitting on a narrow tube or watched a poorly fitted time trialist perched on the end of their saddle rather than through the widest part of the saddle (which is a separate blog at a later date). In these the examples the body is defining its stable reference point for power at the shoulder girdle – resulting in neck and shoulder tightness. The saddle provides a significant mechanical advantage and as such not only needs to be the right width, it also needs to be set up correctly.
Saddle position comes with good bike fit. You can have the right width saddle, but if you are too far forward, aft, high or low there will be a compromise. I often get people coming to see me with SMP saddles, saying they are disappointed that the seat didn’t work for them like it had for their mates. The SMP is a great saddle with a great size range (most important), a generous cut away, long rails (for adjustment) designed by an urologist. They do require specific set up, but once in the right place they are a fantastic saddle. Specialized have just brought out a new size range in the Romin range, which is also great – a reasonably priced saddle, good cut away, good rail length and light. There are other saddle companies that offer good saddles, but most are limited to smaller sizes – which isn’t a problem as long as it is your size.
There is an interesting historical note to saddles. In the 1980′s most bikes would come with a 150mm wide saddle. In the 1990′s most bikes would come with 140mm wide saddles. From the 2000′s most saddles on bikes bought off the floor in a bike shop are 130mm wide. In my experience (dealing with a sample size of over 5000 bike fits), the average male sit bone width is 140mm and the average female is 150mm (again these are my observations), why are saddles getting smaller? The answer here perhaps lies in marketing, a narrow saddle simply looks faster, sleak and less bulky. Coupled with the fact most Pro riders are small and fit 130mm saddles, this width saddle will be the standard that comes with your bike. I find it interesting when I hear cyclists say they love their Brooks or Rolls saddle (the Brooks “narrow” saddle is 150mm) as they are so comfortable compared to other saddles – they have simply found a saddle that fits their sit bone width.
Saddle width is often overlooked when purchasing a bike and in bike fit, getting it right will go a long way if you spend a long time in the saddle.