What ....... did you think I was making it up.
I have to confess that after spending hours of each week keeping residents in the Nursing home comfortable and positioning them in bed with pillows in the correct positions to avoid the shear forces creating Pressure Sores or Ulcers it was after doing the extra education available about all things in regards to better Nursing that one day I realised it was in fact these very same forces causing the pain created by the shearing force causing firstly the numb bum and then the burning like pain so after some experimenting with different pieces of foam under the sheep skin to find the reason behind the Triumph seats problem and what was needed to correct it, I also while pondering for hours in the shed I happen to notice there were stress signs in the seats covering of the forward pushing shape.
The lighter members possibly would not have this problem as much and also the Roadsters as they take some of their weight on their feet which would reduce the shear forces as well, it is one of the reasons I like the boards as I can relax my legs and reduce the pressure on the cranky knees