Extreme physical
exertion to the point of almost giving up. Derived from bike racing in the
olden days when bike seats had rivets, and in an effort not to
get dropped one would slide forward on the saddle to exert maximum pressure on the pedals so as to hang on the the amphetamine-loaded Belgian in front of you.
Person 1: So
how'd you do?
Person 2: Dude, I was on the rivet for like
an hour until I finally
blew.