Originally Posted by Clang

It's easily bad depictions of bikes: lazy illustrators and sculptors who don't want to use reference so they draw weird frame angles, missing tubes (chain stays especially), brake levers but no brakes, hubs that look narrow and pinched, handlebars sprouting out of the top of the fork with no stem, drivetrain on the left, etc. The more respected the artist, the angrier it makes me.

Example: Note the bent fork, 0 cm length stem, cranks that aren't opposed, drivetrain not hooked up to the rear wheel, and the seat stays and seat tube meeting somewhere in the middle of the saddle.