Drum brakes are reliable, low maintenance and aerodynamic with very little of the brakes mechanism out in the wind as it is all encased in the hub shell. The long lasting brake shoes can go tens of thousands of miles between replacement and require very little maintenance other than some cable adjustment as they slowly wear down.
Most of our trikes use 90mm Sturney Archer drum brakes they are powerful and very reliable. Ideal for fully loaded touring and have great stopping power especially for heavier riders and for people looking to do a lot of touring with heavy camping loads.
We also use 70mm drum brakes on our VTX and Sprint X custom race wheel set. They are lighter than the 90mm drum brakes but still offer exceptional braking performance, stopping power and reliability.