World Bicycle Relief explains that its Buffalo bicycles are designed to be “extremely durable to serve the needs of people who travel long distances over rugged terrain with heavy cargo in some of the world’s harshest environments.” With that in mind, simplicity and ruggedness are absolutely critical, and the redundant chain system is designed to provide a high/low gear solution that involves as few breakable, externally mounted parts as possible. These bikes are being delivered to places that don’t have access to bicycle shops or spare part overnighting, so making something that’s as tough and easy to repair as possible is an essential part of WBR’s job.
Now you get to deal with chain stretch on two separate chains without a way to properly tension the longer one.
It’s a tradeoff. Worry about a derailleur in rural Africa, or maybe have a chain issue.
But from what I understand, it runs like a single speed bike, so chain wear would be at 1%, possibility after thousands of KM.
I think it’s a better system than what’s currently available to riders in those areas.
When I was using my fixed gear bike for my daily commute (30km+) it took a long time for my chain to stretch by a little and it took much more constraints than a single speed gear, I wouldn’t be really concerned about this
And the chain has to be quite loose on a single speed for it to fall compared to bikes with derailleur