Effective Surface Flexibility: The Saddle’s 4th Dimension

We’ve been asked many questions about different aspects of a saddle and noted recurring misconceptions people have. In this short article we address two of them:

  1. A saddle with less padding is less comfortable than one with more.
  2. A different saddle with the same shape will work just as well.

The key in understanding why the two statements above may not always be true lies in how the effective saddle surface flexes while pedaling.

Effective saddle surface

Saddles typically include padding and cover on top of its shell, all three of which deform to some extent with force. To simplify things, we consider the effective saddle surface, which we define to be the saddle area in direct contact with our body. This effective surface is two-dimensional, i.e. it has no thickness.

Effective surface (right) is the saddle area in contact with the body.

After making and testing saddles with varying surface flexibility, we observed that in general, the more flexible the surface, the greater the comfort.

The easiest way to think about this is to consider a saddle that has a lot of padding: we expect this to feel very comfortable (at least initially) while riding. If we think about its effective surface, it flexes noticeably when we sit on it and when we pedal.

False — ‘Less padding = less comfort’

With that in mind, imagine a saddle with less padding but with a flexible shell. Its effective surface is as flexible, and will therefore feel just as comfortable. Interestingly, shells with increased flexibility can even feel softer while pedaling, something which surprised us initially.

False — ‘Same shape = same comfort’

The second observation we often make is that most people seem unaware of the importance of effective surface flexibility. They look for saddles with shapes similar to those they know have worked for them in the past, and assume that they will be just as comfortable.

The fact is that it is difficult to deduce the comfort of a saddle based solely on its shape. Unfortunately, there is no standardized way of conveying effective surface flexibility. Manufacturers indicate whether their padding is ‘soft’, or ‘firm’. And perhaps say that their saddles’ nylon shells are more flexible. This non-standardization of flexibility, and indeed riders’ general unawareness of its importance, complicates the saddle selection process.

If a flexible shell is sufficient, why do we have all these saddles with thick padding?

Mass produced saddle shells are typically made of some sort of plastic and not that strong: over time with usage, they will fatigue and crack. To prevent this, shells are made thicker, which in turn means they are stiffer. To deal with that, manufacturers add padding. If instead we begin with a flexible and strong shell that doesn’t fatigue and crack over time, then we don’t need as much padding.

Can padding be bad?

At this moment, we believe that

  • Excessive padding can result in pressure in undesirable places, e.g. upwards on the perineum, as well as chafing.
  • While all padding will compress, poor quality padding collapses easily, and can be permanently deformed over a short period of time rendering an initially comfortable saddle unusable, sometimes even over the course of a ride.
  • Without a sufficiently flexible shell, thinner but firmer padding won’t result in a flexible effective surface, and hence doesn’t feel as comfortable.

Won’t the chamois help?

The chamois does change the effective surface’s shape and flexibility. It is similar to saddle padding, with the additional consideration that its positioning against the body needs to be managed. If the chamois is too far forward, it can cause chafing with the saddle edge. If too far back, it may not adequately cover the body surface in contact with the saddle. Similar to saddle padding, chamois collapses over time. Less expensive chamois in general can even collapse completely by the end of a ride.

In short, while thicker chamois can help, they may require more effort to ensure they work as intended.

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