|Here's a hub with a flanged cup in place at the top, and another cup on the table|
|Here's the same hub with the bearing cup knocked out|
Cups come in different sizes, based on outside diameter, and also come with or without a flange.
|Here's a few new hub cups, small at the front, big at the back, flanged on the right, plain on the left|
It's not easy to get replacement hub cups, but it can be done (I remember buying bike hub cups from a small town bicycle shop in Thailand in 1993). In Australia, bike shop owners can buy hub cups from a major wholesaler, Bicycle Parts Wholesale (they don't retail). Aliexpress also has several vendors selling hub cups, if you want 10,000 pairs.
We recently repaired an old front hub with new cups (bought through a wholesale account). The hub itself was quite interesting, apparently spun from aluminium tube.
|looking into the spoke holes you can see the flange is made of 2 layers of folded pipe|
|Here's the reconditioned hub (new cups, re-ground cones) ready to lace into a rim|