There's this great website called Shanghai Solved where you can post a question about Shanghai & one of the other members will answer you.
Several weeks ago, one of the members posted a question about where to buy shoes for big feet in Shanghai, & another member posted an answer recommending a store on the other side of town.
I took down the address, printed up a map, & went in search of it on my day off. After several wrong turns, I found the store in an alleyway, up a set of stairs, & with no other signage anywhere except for this declaration on the door.
work, & maybe some new tennis shoes.