I can do 80kgs benchpress but still can't do a single pull up. What is the problem?
This is how you can do pull up successfully :
This is very good question and a very common problem, I have seen guys with very good otherwise exercise capabilities sucks in pull up, whereas some skinny girl may come in front of you, get away with doing pull up easily. Don't be embarrassed, guys, okay. I am going to give you many solutions, you can try whichever you like or could try all of them.
[Solution no 1]