Hip Rotation

We’ve recently been talking to cyclists who aren’t sure why saddles with gradual tapering (also called V or pear-shaped saddles) are useful. We describe in this short article how it is related to the rotation of our hips while pedaling.

First, a few graphical representations of the sitbones and rami:

Representation of hips, seen from the right
Representation of hips, seen from above

Riding postures

When we ride with an upright posture, our weight is primarily supported by our sitbones. This is especially true when we are not in an aggressive posture and/or our saddle-to-handlebar drop is low:

Upright posture: only sitbones support our weight

In the upright posture, the saddle must be wide enough for our sitbones to support our weight.

When we adopt an aggressive posture and/or have a significant saddle-to-handlebar drop, two scenarios are possible:

More aggressive postures: (a) bending at waist (b) hips rotated forward

(a) Keeping the hips upright, we bend our waist in order to reach down to the handlebars. As before, only our sitbones support our weight.

(b) The alternative is to rotate our hips, with our backs remaining relatively straight compared to (a). Rotating our hips brings the rami in contact with the saddle, allowing the former to bear weight in addition to our sitbones. In the case of extreme postures, e.g. time-trial, our sitbones can lift off the saddle and all weight is then borne by the rami.

Saddle shape and hip rotation

With hip rotation, V-shaped saddles provide more support as there’s ‘more saddle’ underneath the rami. On the other hand, T-shaped saddles remain primarily supporting the sitbones, which means that attempting to rotate our hips further can cause pressure to be placed on our perineum instead of our rami. Consequently, T-shaped saddles are less suitable for hip rotation.

With hips rotated forward, (a) T-shaped saddles provide less support for the rami, unlike (b) V-shaped saddles

There is the misconception that V-shaped saddles always interferes with the inner thigh while pedaling: in fact, it interferes only when the saddle shape does not fit. Due to the need to support both our sitbones and rami, finding a V-shaped saddle that fits may be more difficult.

Pros and cons of hip rotation

Hip rotation, together with a V-shaped saddle, allows the distribution of weight over a larger contact area, thereby reducing pressure at any one spot. This usually leads to more comfortable riding, and is helpful for those suffering from soreness around the sitbones during and after riding.

Due to the larger contact area, V-shaped saddles usually also provide more freedom to move around the saddle lengthwise. For cyclists who sprint on the nose or hammer for extended periods of time, this can be invaluable.

The downsides to hip rotation include:

  1. Potentially having to assume more aggressive postures, which in turn requires a stronger core (i.e. more exercise off the bike).
  2. More pressure on the perineum. An increase in perineum relief is likely to be required even when the rami is bearing weight. That is, if we normally use a saddle with a channel, a cutout may be necessary instead.

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