1) Narrow quill pedals with tabs at the end of the cage to neatly hold a toe strap.
I wanted to have my feet be snug as a bug in a rug with these - but I always got jammed on the outer part of my (D-width, not really what I consider wide) feet.
2) uncomfortable cycling shoes. I had the old Puma shoes where the stiff leather and shallow toe box just killed my feet.
3) Aluminum rims that would go out of true all the time.
4) Handlebar stems with no removable faceplate.