Once upon a time your options for saddles were basically either a Turbo or a Rolls. Happily those days are now well behind us as there are a plethora of saddle options available. Not only brands and models but different widths of those models. How can we compare them?
By measuring them and analysing the numbers of course! Understanding what the important differences are in saddle measurement makes choosing your next saddle (or preserving your position when you change saddles) much easier.
Ideally, we contact the saddle with our Ischial Tuberosities (sit bones). If your position is good and you have a saddle that suits you then most of your weight will be on these bones rather than the soft tissue of the Perineum.
As far as I’ve been able to determine from Anthropometric data (aided by examination of a model of the Pelvis) the width across the sit bones is generally 90mm – 120mm.
So I constructed the highly sophisticated measuring jig shown to the right. A spare piece of wood, a pair of nails and a steel rule allow me to consistently measure the distance from the saddle nose to the point where it is 90mm wide.
This 90mm width point serves as an approximation of the true sitting (contact) point.
So when I swap saddles over I take account of the setback to the contact point rather than just to the saddle nose.
As an example of the benefit of this approach, consider the San Marco Aspide Glamour and the Selle Italia SLK Lady. My wife uses the SLK Lady with a setback of 105mm from the bottom bracket to the nose of the saddle. When she trialled the Aspide Glamour I changed that to 85mm to account for the nose being 20mm longer on the Aspide Glamour (164mm vs 144mm). Otherwise she’d have ended up sitting much further back.
It’s pretty common for people to completely throw their position away when they change saddles, especially now that there is more diversity in shapes.
So, next time you’re thinking about trying a different saddle, make sure you match your true sitting position, rather than just using the saddle nose to replicate your position.