Some companies, especially Thorn Cycles of England, popularize the 26" mountain bike wheel size for touring bikes, whether for off-road or on-road use. Others such as Roberts and Hewitt have followed, and offer 26"-wheeled touring bikes alongside conventional 700C machines. Advantages of the slightly smaller wheel include additional strength, worldwide tire availability, and lighter weight. Some touring bicycles, such as the American Surly Long Haul Trucker are built around 26 inch (or 650C) wheels in smaller sizes and 700C wheels in larger sizes, as the larger wheel can compromise touring geometry in a small frame.
While more 26" inch tires are made for mountain bikes (and so are too heavy and deeply treaded to be useful on a road touring bike), specially touring tires for 26 inch wheels are now widely available in developed countries. Riders leaving areas such as western Europe and North America, where cycle equipment is readily and widely available, nevertheless often prefer 26-inch wheels because mountain-bike sizes are often more easily obtained in the Developing Contries. The Fédération Française de Cyclotourisme's mass ride from Paris to the Beijing Olympics in 2008 insisted all riders use 26-inch wheels for that reason.
The difference in rolling resistance between sizes and widths is debated; what is clear is that factors other than wheel size (air pressure, tread, tire width) play a more important role than than the wheel size
There are numerous variants on the traditional road tourer depending on the weight carried and the type of terrain expected. Expedition tourers are strongly built bicycles designed for carrying heavy loads over the roughest roads in remote and far-flung places. These range from simply being mountain bikes equipped with racks, panniers, mudguards and heavy-duty tires, to purpose-built bicycles built to cope with long-haul touring on tracks and unsealed roads in developing countries throughout Asia, Africa, and the other continents. Their frames are often made of steel as any breakages can be welded and thus repaired in towns all around the world.
Most riders who show accounts of their tours at the Cyclo-Camping International meeting in Paris each winter use mountain bikes.
Touring bicycle frames typically have a long wheelbase and stable steering geometry, with numerous attachments for luggage racks, fenders (mudguards), lights, high capacity water bottles, tools and spare parts. Chainstays must be long enough to accommodate panniers without them brushing the rider's heels, and the entire structure must be stiff enough to safely handle long, fast descents with the machine fully loaded.
Touring bicycles traditionally employ wide-ratio derailleur gears, often with a very low gear, referred to in some countries as a "granny gear", for steep hills under load. Internal-geared hubs have become popular in recent years because of their robustness and low maintenance.
Touring bicycles are mostly equipped with linear-pull brakes or cantilever brakes, instead of the caliper brakes used on racing bicycles. The need for mudguard (fender) and wide tire clearance preclude the use of caliper road brakes, which may be excessively large and flexible if made to fit a touring bike. Some newer touring bicycles use disc brakes, because of their superior stopping power and also to avoid carrying and changing spare brake pads.
Thus, touring bikes trade speed for utility and ruggedness. This combination is popular with commuters and couriers as well.