I think there's a misunderstanding somewhere! You say the measured distance from mark to floor is 76cm, but your inside leg is 83cm!!? The whole point of the measuring thing is to accurately measure your inside leg - where do you get 83cm from? Here is another way of looking at it: http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR&SITE.CODE=&gender=M&units=cm
I think there's a misunderstanding somewhere! You say the measured distance from mark to floor is 76cm, but your inside leg is 83cm!!? The whole point of the measuring thing is to accurately measure your inside leg - where do you get 83cm from? Here is another way of looking at it:
http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR&SITE.CODE=&gender=M&units=cm