I have a 1975 Bob Jackson and I can't seem to get the post tight enough to stop moving. The tubing is Reynolds 531 and the Factory confirmed it was made in 1975. A 27.2 fits in the tubing well but when I tighten the binder bold all the way it doesn't put enough pressure to hold the seat firmly in place (it is tightened to the end). The binder bolt if fairly short and I don't know if I can get a smaller one.
Do I need a bigger diameter post? Should I add a washer on the binder bolt area to increase the pressure?
Any help is appreciated.