Road bicycles frames with top tubes parallel to the ground. The current trend toward slanted top tubes on everything looks ugly as heck to me (I'd give an exception for MTBs). They can be steel, aluminium, carbon models, nice artistic lugs or even well-taken-care-of 1960s era Schwinn electroforged frames, and even have larger-sized tires (over typical 700x23-35 tires) and drop or flat handlebars.