No currently-manufactured bicycle drum brake I've heard of has good stopping power. I've even bought a Worksman bike new that had one. Functionally, the front drum brake was ,,,,uh,,,, "lacking".
I tried different stuff to help it, but the main problem is that the whole brake-actuator arm mechanism is thin and flexy. The only way I could see to fix it would be to machine a whole new actuator side that was stronger.
What I have heard of motorized bicycle guys doing is using moped hubs instead.
They are a hassle to obtain and much heavier, but then again--the bearings are pretty much bombproof for a bicycle. And the brakes are actually functional.
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If you were doing something and had to have axle brakes but wanted to stick with bicycle parts, I would take a look at the Shimano roller brakes. These have the lowest braking power when compared to disks or rim brakes, but they're still way more powerful than the drum I've seen.
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