April 13, 2021, 11:54 a.m.
Saddle height and saddle setback are effected by the rotation of the Pelvic, It follows that if your saddle height changes or your back angle changes it has an effect on the contact between the Ischial Tuberosity and saddle.
Since 2007 Saddle manufacturers have been producing different width saddles to better suit the riders individual Sit-bone (Ischial Tuberosit) width. Common sizes are 130mm, 138-143mm, 145mm, 150mm and 155mm options are used now as standard sizes. Companies such as WTB (Wilderness Trails Brand) have taken a slightly different approach to the Sit Bone width by using a comparison of your wrists. Read ( https://www.wtb.com/pages/fit-right-system ), read
Specialized have taken it digitally with by using a pressure mapping sensor, ( https://www.retul.com/dsd )
Regardless of how you arrived at your saddle choice it is important to set the saddle in the correct position on the bike, remember that on a standard road bike the rider is leaning forward to reach the handlebar resulting in a back angle ranging from 42-47deg from horizontal.
The best way to make your saddle position neutral should be based the saddle profile. (Profile when looking from the side)
Use a level to find the lowest point in the saddle profile, then half the rear of the saddle by finding the lowest to highest part of the saddle, once you have this position the saddle can now be adjusted to a neutral by the use of a level.
Place the end of the level on the position you have now marked as being the middle of the lowest to highest point, then extended the level forward over the highest point at the front of the saddle. This now is the neutral level position for all saddles. (There are a couple of different shape saddles such as Selle SMP and Cobb) where the manufacturer state the saddles should be positioned based on the rails but this is not perfect and the above method will still work.
and not on the saddle being levelled at the two highest points.
Regards Gary Land