We were fortunate to have uphill headwinds on the downhill side of the Tien Shen mountains in Western China, or it could have been a problem. Our loaded tandem, including us, weighs around 400 pounds. That weight puts such pressure on standard brakes and brake pads that we risk an exploded tire from overheated rims, not a good thing at speed down a steep mountain.
When the nearest bicycle shop is hundreds, even thousands of miles away, we have to be prepared to fix most problems. I carry up to a kilo of tools and spare parts to fix most of the mechanical failures we might encounter after travel on bad roads, and dirt tracks.
In the third world/developing world, your flat might just occur in an exposed location, putting you in potential danger, or at the least surrounded by a vociferous curious crowd throwing questions at you in a language you don’t understand. A little pantomime and wide a wide smile usually takes care of this, but it plays hell with the concentration. You don’t want flats.
When we travel on our tandem in difficult places, like Tibet, and SE Asia, keeping the bike clean is the last thing I’m thinking about at the end of a hard day: food, a place to get horizontal and sleep are first priority, maybe changing money, buying food for the next day, trying to understand your host, the market vendors; all this before sunset since it’s often cold then, or sometimes not the best time for a gringo to be wandering the streets. So this is often when the derailleuer looks like after 3 or 4 thousand miles.