Classic touring bicycles —the kind you see loaded down with front and rear panniers, pictured trucking along Route 66 or across the Continental Divide— share a number of common characteristics:
Chromoly steel frame. Though not as light as more modern frame materials such as carbon or aluminum, steel is durable, capable of being bent and repaired without cracking, and is inherently flexible, which makes it comfortable to ride on over miles and miles of road.
Upright geometry, which allows the touring cyclist greater comfort over long miles, as well as the ability to view the scenery without getting neck cramps.
Long wheel-base and long chainstays. Because speed and agility are less crucial in long-distance touring than stability, touring bikes can be considerably longer than conventional bikes. They’re designed to be stable under heavy loads and on long descents. It is no accident that one of the most quintessential touring bikes is called the Long Haul Trucker — that’s what these bikes do.
Bomb-proof wheels. The wheels of classic touring bikes are usually 700c with a high spoke count (32 or 36-hole), and durable, puncture-resistant tires to handle lots of road miles. Touring cyclists who visit very remote areas of the globe sometimes prefer a 26” wheel set, because those can be more easily serviced in areas without modern biking shops and facilities.
Serviceable components. Classic touring bikes have rim brakes, but mechanical disc brakes are starting to take over the category. Hydraulics are generally avoided, since they may not be easily serviced if you happen to find yourself in the middle of nowhere. Bar-end shifters are common on touring bikes since they can be serviced or replaced more easily and economically than the more ergonomic integrated shift/brake levers.
Drop bars or other multi-position handlebar, so that you can change where you place your hands and how much you lean over the many miles of riding.
Carrying capacity. Touring bikes have ways of mounting front and rear pannier racks and fenders.
For short tours, overnights and bikepacking adventures, see also Gravel & Adventure Bikes.