That, in and of itself, is a problem. Low gears put much higher loads on a chain than tall gears. Look at the lever arms, a 42T chainring puts half the load on a chain that a 21T does at the same pressure on the crank. MTB's break chains as a result of their extremely low gears, 20x34 is common, not just wear from abrasive riding conditions.
Compounding the problem is the extra luggage weight (20 to 50+ pounds) on the bike and you have tourists putting significantly more demands on their chains than regular road riders.