getting the full post in here:
One of the things I found toughest to understand when I started designing shoes was how much the most subtle change in proportion altered a concept. Boots, Basketball Shoes, Trainers, Running Shoes, Athletic Lifestyle Shoes, Flats, Pumps, Mary-janes all have very specific shapes. When you understand these shapes, you can subtly push them. When you don’t, you scratch your head and wonder why your shoe doesn’t look right.
Above are three simple proportions. The top one is a Basketball Shoe, but it could easily be a Hiking Boot if the collar was raised and the toe box thickened. The second is a Running Shoe, but it could easily be a Trainer with a little thickening. The bottom shoes a low profile athletic lifestyle silhouette.
Above you can see how a few simple lines make these proportions come to life. These designs are pretty conservative. But from here you can start to push new concepts. In order to break the rules, you first need to know why they exist in the first place.