I hang my Homage which has no top tube (being a step through) from the seat post. As I ride a large version my seat post normally sticks up less than three inches, I extend the seat so that there is a solid six inches of tubing to hold on to. Don't worry about clamping on to the square tubing but just extend your seat post and clamp on to that. As the bike is not really well balanced hanging it that far back, I put an upside down bucket under the front wheel once it is up on the work stand. That stabilizes it just fine