In our previous two blog posts we've learned what our sit bones are, how to measure them and how this impacts our choice of saddle. In this post we'll discuss the many other factors that must be considered when choosing a saddle. These include roll-off or curvature left to right, curvature fore/aft, taper rear to front, nose width, nose length and the presence or absence of a pressure relief channel or cut-out.

*Images above were identified in our previous post (part 1). Please review that post for details.

The goal is to find a saddle that matches the shape of your pelvis and suits your style of riding. Such a saddle will distribute pressure as evenly as possible, over as great an area as possible without inhibiting your pedalling, to minimise or eliminate discomfort or irritation.

The amount of overall pressure you feel when you sit on your saddle can be summarised as your weight divided by the area of the saddle that supports your skeleton and soft tissue. The regions of your skeleton and soft tissue that support the most weight will experience the greatest pressure. Therefore, more 'sittable' area generally means less pressure overall, although being comfortable requires the saddle shape and setup to be right for you.

Roll-off

We've previously mentioned the left to right curvature of the saddle when discussing the 'sittable' area or width. This is usually most obvious when viewing the saddle from the rear. The roll-off, or how quickly the saddle curves downward from centre to the sides or wings, will affect how your pelvis engages with the saddle. This, in turn, affects how pressure is distributed across your skeleton and soft tissue.

Too much roll-off for your pelvic shape and you may feel excessive pressure against soft tissue in the region of the perineum and/or genitals. This is because the skeleton (sit bones and ischiopubic rami) isn't being properly supported by the wings until the highest point at the centre of the saddle is already pressing firmly against soft tissue. The result is that the highest point of the saddle bears too much weight, and creates greater pressure, under the perineum and/or genitals. This can be very uncomfortable and even cause numbness. 

Too little roll-off, or put another way, a saddle that is too flat from left to right for your pelvic shape, can result in too much pressure in a very small area beneath the sit bones. This is because almost all weight is being borne on a very small area of your skeleton and is especially the case if you sit fairly upright. While thicker padding may provide initial relief from sit bone discomfort, padding will compress over time and become less effective. The better approach is to have your bike fitter check your saddle setup and if you are still uncomfortable, try other saddles. 

Fore / Aft Curvature

When looking for the optimal saddle for your pelvic shape you must also consider the curvature of the saddle from front to rear. The following is a guide used by most saddle manufacturers and referenced in their saddle selection criteria, for those that provide them. While I wouldn't call it a 'rule', it does seem to be very consistent across the bicycle industry and provides a useful starting point. 

Saddles that are flatter front to rear tend to be marketed to riders with an aggressive position, which typically means lots of anterior or forward pelvic tilt and a low torso. It is implied that these riders possess greater than average flexibility. Regardless of why the rider adopts this position, the flatter saddle provides a neutral platform on which they can easily rest their ischiopubic rami. It also seems to be assumed that these riders appreciate the ability to move around freely and locate their pelvis almost anywhere on the saddle to optimise their position for climbing, descending, seated sprinting, etc. Examples of such a saddle include the Selle Italia Flight range, Pro Falcon, SQlab Ergowave 612R and of course, some TT or Triathlon saddles.

Saddles that are slightly curved front to rear or have at least some variation in the height of the saddle across its length, tend to be marketed to riders with mild to moderate anterior pelvic tilt. This is the majority of riders and is consistent with little to moderate saddle to bar drop and potentially - although not a 'rule' - average flexibility. The slight curvature is designed to help the rider locate their pelvis at in ideal point on the saddle and then gently cradle their pelvis. The rear of the saddle generally rises to provide support at or behind the sit bones. The front of the saddle tends to slope slightly upwards to meet the ischiopubic rami and allow them to bear some weight even though they are not quite horizontal. Examples of such a saddle include the Pro Turnix, SQlab Ergowave 612, Selle Italia SLR range, Ergon SR Pro and many others.

Saddles that are heavily curved front to rear tend to be marketed to riders with a fairly upright posture, those with below average flexibility, or those who struggle to maintain an ideal location on the saddle. The pronounced curvature firmly cradles their pelvis to minimise or eliminate fore/aft movement and provide clear proprioceptive cues to improve stability and overall position. These saddles can be more challenging to set up correctly as they rarely have any truly horizontal surface. This makes it difficult to gauge whether they are set at an ideal angle, or nose up/down tilt, without referring to the manufacturer's instructions. They can be less forgiving than other saddle types as they eliminate the possibility of moving around on the saddle to accommodate other shortcomings in overall position. Examples of such a saddle include the Selle Italia Novus range and the infamous Selle SMP range.

Taper

Taper refers to the profile or shape of the saddle as viewed from above. A saddle with fast taper will narrow quickly from its widest point near the rear, to the narrowest point near the front. A saddle with slow taper is, therefore, the opposite of this. It will maintain much of its maximum width for some distance as it tapers from rear to front. While there is no direct correlation between sit bone width and ideal taper, wider saddles do tend to have slower taper. There will, of course, be exceptions to this. However, given the wider starting point, even a 150mm saddle with fast taper will be wider for most of its length than the same saddle that is, for example, 132mm at its widest point.

Determining the taper that is ideal for you requires test riding the saddle or reflecting upon your experience from previous saddles. Finding the right mix of 'sittable' area towards the rear of the saddle and clearance between and behind your thighs can be challenging. Two signs that the taper is too slow or that the saddle is simply too wide include:

1. Chaffing as your inner thigh rubs against the sides of the saddle, or

2. Catching the rear of your thighs on the front edge of the wings as you transition from downstroke to upstroke while pedalling.

Nose Width & Length

Nose width and length are generally a matter of personal preference. A wide nose can provide a more stable platform for those who spend a lot of time at the front of the saddle. Perhaps they spend much of their time climbing or perhaps they routinely adopt a very aggressive position. As long as the width of the saddle at or closer to the nose doesn't cause chaffing against their inner thigh of course.

A traditional, longer saddle nose can provide a greater variety of positions for riders who choose to take advantage of that. A longer nose can also provide additional, and often subtle, control of the bike by experienced riders as they use their thighs to adjust the lean and shift their weight to influence handling. Some prefer shorter noses as there is less saddle to "get in the way" if they are in and out of the saddle a lot such as when sprinting.

Cut-outs

Cut-outs and pressure relief channels can be invaluable when pressure relief is required under particularly sensitive regions of soft tissue such as the perineum and genitals. Not everybody needs them, but for those who do they are a godsend. In conjunction with the appropriate saddle shape for your pelvis and correct setup, they can relieve and prevent numbness that results from nerve compression or lack of blood flow. Cut-outs and pressure relief channels also affect 'sittable' area and the pressure you will feel under the parts of your anatomy that are in contact with the saddle. 

In some cases, cut-outs or pressure relief channels can create issues. This is usually because they are poorly positioned, too small or a shape that is incompatible with your pelvis and soft tissue, have harsh edges that irritate soft tissue, or use inappropriate padding. There can also be too much of a good thing. Some saddles (no names in case someone gets upset) have extremely large cut-outs that almost guarantee your most sensitive bits will never come in contact with the saddle. Unfortunately, for some people this will mean that there isn't enough 'sittable' area left to comfortably support the regions of skeleton and soft tissue that do come in contact with the saddle. The additional pressure on those regions can create discomfort.

Our next blog post will address the critical issue of overall position on the bike. It is universally applicable to all saddles that all aspects of your position should be as close to optimal as possible before insisting that the saddle is the source of your discomfort. We will discuss saddle height, fore/aft position, angle or tilt and reach to the handlebar and controls and what effect each have.