How to Choose a Road Bike
If you're considering purchasing a new road bike, or just studying up on the subject for future reference, there are basically three things to know about road bikes: frame materials, frame geometry, and components.
First: Materials. Manufacturers, these days, make bikes from four materials: aluminum, steel, carbon fiber, and, to a lesser degree, titanium. Each material has different properties that lend a different feel to the ride of the bike. Manufacturers sometimes use a combination of these materials in order to achieve particular ride characteristics they want in the bike.
Aluminum is by far the prevalent material used by bike manufacturers today. Builders like aluminum because it is lightweight and stiff. With aluminum, they can make stiffer frames that flex less under load and thus direct more of the rider's energy into forward motion. However, because it is stiff, aluminum can lend a bumpy, less comfortable ride to the bike.
Steel on the other hand, which has been used to build bikes for decades, gives a smoother, more comfortable ride to the bike. It is a more pliant material, and therefore, absorbs road vibration well. Steel is also a very strong and reliable material. It weighs only a little more than aluminum.
Carbon fiber, though, touts the best qualities of both steel and aluminum. It is both lightweight and lends a very smooth ride to the bike. Carbon fiber is also a very versatile material. It can be laid out to be either stiff or compliant, depending on what part of the frame it is used in, and depending on what ride qualities the builder wants in the bike. We're seeing more and more carbon fiber used on bikes these days. The technology has advanced, and the price is coming down.
Titanium, on the other hand, has not come down in price. Besides being an expensive material, a lot of hand work goes into building a bike with it. Titanium is an extremely hard metal and difficult to work with. It most resembles steel in its ride qualities in that it gives a very smooth ride. However, it has the advantages of weighing less than steel, being very corrosion resistant, and incredibly durable. Incidentally, Litespeed, one of the most highly regarded titanium bike makers, is located just up the road from Atlanta near Chattanooga.
Second: Frame Geometry. As the term implies, frame geometry refers to the lengths of the frame tubes and the angles at which they are assembled. The frame geometry, like the frame material, effects how the bike rides. More specifically, the frame geometry determines how the bike handles. A touring bike, for example, has a longer wheelbase, more fork rake, and less acute head and seat tube angles. As a result, a touring bike handles more like a Mercedes or a Lexus: smooth, stable, and comfortable, desirable qualities for a bike to be ridden great distances, loaded with heavy gear, or used for commuting. Conversely, a bike made with more acute frame angles, a shorter wheelbase, and less fork rake, handles more like a Porsche or Ferrari: light, quick, and responsive, desirable qualities for racing or for just the joy of performance.
Third: Components. The components used on a bike, i.e. the wheels, brakes, derailleurs, etc., also contributes to a bike's ride quality. Higher quality components are made from better materials, machined to closer tolerances, and have finer finishes. That means they work better and last longer. The shifting feels crisper, more precise; the braking faster and more controlled.
The Shimano brand dominates the bicycle parts market, especially the transmission market for road bikes. (Of course, Campagnolo, the classic Italian manufacturer, still makes fine road bike components, but not really on the scale of Shimano.) When you hear mention of words like "105" or "Ultegra", for example, these are references to the model of Shimano components used on the bike. Most manufactures will make a bike featuring each of these model component groups and they typically sell at about the same price points. "Dura-Ace" is the top of line component group where Shimano does all of its research and development. It is very expensive stuff, but the technology developed there gradually filters down the line to the less expensive component groups, namely: Ultegra, 105, Tiagra, and Sora.
Now that you know the three fundamentals of road bikes: frame materials, frame geometry and components, here's how you buy a one.
Find a bike shop you like, consider the price range bike you want to afford, determine your proper frame size, then test ride some.
Your Bike shop: It's nice to establish a relationship with a bike shop. You'll be going back for service, accessories, and information; and knowing the folks at your bike shop simply makes your visits there more enjoyable. It's a relationship kind of business. Moreover, a good shop will fit your new bike to you properly, (Having a good fit is especially important on a road bike.) show you how to operate it, and introducing you to all things cycling.
Price: Let your intended use, not just your budget, determine what you spend on your new bike. Of course, the more you ride, the more you may want to spend on your bike. Remember too that this is a long term purchase. Get what you want. You'll have your bike for a long time.
Size: Manufacturers measure their bikes differently. Thus, you may ride a different size bike in a different brand. That's OK. In any case, you determine your proper frame size by standing over the bike. You should clear the top tube on a road bike by an inch to an inch and a half. (The clearance is mainly a safety issue so that you don't injure yourself when stopping, starting, or getting on and off the bike.) The other critical dimension to be aware of when sizing your bike is the reach from the seat to the bars. The proper reach depends on the type bike, the type of riding, the build of the rider, and sometimes other considerations such as injuries or back issues. The reach can be better assessed on a test ride, which is the next step in selecting your new bike.
Test ride several bikes. Simply observe how they fit, feel, and handle. Note that the fit and feel of any particular bike is not defined by any single element, such as the frame material, but rather by a combination of elements: the frame materials, frame geometry, and components. Be sure you are comfortable on the bike. Try out the brakes and gears. Also test ride some bikes at different price points. Although, you'll find that the features don't really change as you go up in price, you'll notice that the better bikes will have a smoother, lighter, more solid feel to them. You'll be able to feel the differences from bike to bike when you ride them, even if you don't have any experience.
You'll find that bikes are very competitively priced from brand to brand and store to store. At a given price point, you'll see similar, if not identical components used on them. It's fair to compare bikes by its price. If one bike cost a hundred dollars more than another, then there are a hundred dollars worth of better components on it somewhere. Thus, you can focus your attention on how the bikes fit and feel, not on just what they cost. You'll know when you find the right bike. It's sort of like buying shoes. When you "try on" the right one, it just feels good. Enjoy the process.
Happy Trails
Mike