a hanger
A hanger is a free-loader who clings to people like a smelly sock in a sock drawer, always trying to get a ride or a break.
"I'm not a free-loader. I'm a strategic rider.", Jake, who's been riding with the same group for years
"He's like a shadow, always there but never noticed.", Lisa, watching her friend
"He's a hanger. He just wants a free ride.", Emma, watching him ride with the group