It's all about comfort. Just about any mountain or comfort bicycle can be made to do for a weekend overnight tour but for ‘round-the-world work you will need a specific kind of ride. You might think that durability is the most important characteristic in a touring bike. After all, you don’t want to get stranded miles from the nearest bike shop with a broken wheel. But actually, comfort is more important because if your bike isn’t comfortable you won’t ride it far enough for durability to be a factor.
Comfort is a pretty individual concept. What feels good to a six-foot, 180 pound man would be the Spanish Inquisition to a small woman but there are a few characteristics that you’ll want to look at no matter what your build.
Perhaps the most important one is frame geometry. Bicycle frames come in many shapes and sizes and are constructed from lots of different materials. But generally bikes can be classified by their geometry. By geometry I mean the set of angles at the joints of the frame. Within the spectrum of frame geometries we find racing bicycles at one end and ‘round-the-world touring bicycles at the other.
Before we get into a discussion about geometry it will be useful to talk about the parts that make up the bicycle frame. The classic bicycle frame, whether a racer or a tourer, is a triangle composed of the head tube, the top tube, the down tube and the seat tube. At the front, the forks hold the front wheel and at the rear, the chain stays and seat stays support the back wheel. At the bottom of the frame where the crankset mounts is the bottom bracket shell.
A good ‘round-the-world touring bicycle will be built for comfort not speed. It will have a relaxed angle on the head tube, around 71 degrees, which slows down steering (a good thing) and positions the handlebars closer so you can ride in a more upright and comfortable position. It will have long chain stays so the rear panniers ride farther back and your heels don’t hit them on the backstroke. The longer frame also provides a smoother and more stable ride. The bottom bracket shell will sit close to the ground for a lower center of gravity.
It might seem superfluous to know so much about frame geometry. You might be saying, “Can’t I just go out and buy a good ‘round-the-world touring bicycle from my local shop?” In a perfect world this would be the case but not many shops specialize in touring bicycles let alone ones of the ‘round-the-world kind. Lightweight racing-style bikes are all the rage. They’re sexy, sell for a lot of dough and provide the stores with healthy margins. So there’s a good chance your local bike shop salesperson knows a lot about snazzy go-fasts but next to nothing about touring bicycles. In fact, it’s likely that the shop won’t even carry true tourers and the salesperson might knowingly or unknowingly try to steer you toward a mountain bike or hybrid telling you that they’re just as good as the real thing. When this happens head for the nearest exit, then, find a shop that knows touring and can sell you the right bike or better yet, if you have the budget, have a frame custom built.”
Your bicycle will need to be outfitted with racks, fenders, water bottle cages, lights, and more so make sure there are plenty of mounting points. These mounting points are also called ‘braze-ons’ and they’re simply tabs brazed onto the frame that are usually threaded to accept bolts. There should be two braze-on’s at the bottom of each side of the forks and rear dropouts; one braze-on for the rack and one for the fender. You can get away with mounting both rack and fenders to the same braze-on but it’s better if each component has its own.
There should be additional braze-on’s at the tops of the seat stays for the upper rack supports and braze-on’s enough to accept two water bottle cages on the down tube and one on the seat tube for a total of three. Hey, it can get pretty thirsty out there.
Of equal importance to geometry is fit. There’s no way to know if a bike is going to be comfortable until you ride it for a long distance. And there’s no way to ride a frame until it’s been built up with all the necessary components. Which poses something of a dilemma. The best you can do-if you’re purchasing a bare frame-is to get the seat tube height right. Once you’ve done that you can make a lot of adjustments to fit through stem and saddle placement and crank arm length. Unless you have a very unusual build; very long arms in relationship to your torso for example, a frame with the right seat tube length for your height can likely be made to provide a comfortable fit. Most bicycle frames use the seat tube length measurement to denote frame size. A small frame would measure 40 cm., a large frame would run 60 cm.
Make sure the frame you choose is designed specifically for touring. There are a couple of manufacturers that sell the same built up frame for different types of riding: cyclo cross/touring for example. Avoid these bicycles. The compromises they make to the frame just won’t do for your ‘round-the-world tour.