I offer pure conjectures in response to Amir's question:
1) Not sure about "common," but Sturmey long offered drum-brakes, both front and rear. Indeed, I used to have a pair of BSA 3-speed (rear) and front tandem hubs, for inch-pitch chain.
2) I also had a Schwinn 3-speed derailleur hub with drum brake, from about 1951. Also from a tandem.
3) In the 60s - 70s, we who loved tandems were cursed with the Atom drum hub for 5-speed derailleur. Aluminum shell, oversized spoke holes, weak axle, and (usually) French thread. I was always under the impression that these were a deviant of (based on) MoPed parts.
harvey sachs mcLean va Please note: email address changing to firstname.lastname@example.org
A friend in Paris sent me some photos of a rusty 1940's 650B randonneur frame. It has a center-pull brake mounted on brake bosses on the fork, and no brake bosses on the back. The brake bridge, on the seat stays, is drilled vertically, probably for a fender mount only.
It looks as if the frame was designed for a rear drum brake as it has a braze-on loop on the underside of the left chainstay (to hold the arm on a drum brake?).
Were drum brakes common on high end touring bikes back then? Who made them besides Maxi-Car? Were they wider than standard hubs? Did any maker or constructeur use such hubs regularly? Am I missing something?