What is the name of this movie?

It was made in the 1970's or late 60's, and I only saw a bit of it. But it was this couple and they went to the beach and when they parked their car the man went surfing and the woman was sitting outside and a big group of bikers came up. The bikers were wearing black leather and had black hair. they were menacing. i know this is vague, but my mother made me turn it off because I was young then. They played it on Maori TV a few years ago?