There are customized bikes...and then there are custom-built bikes.

What's the difference between the two?

Cusstomized Bikes

Well, anyone who goes to a bike store and has the clerks there help him, or her, fit the bike properly, will usually "customize" their bike by choosing the kind of saddle they like (narrow or wide, gel-filled, etc.), different stem lengths for handlebar height, v-pull or disc brakes, etc.

You can continue to customize your bike with accessories such as bells, compasses, and lights - and you can even give it a paint job if you're good at that sort of thing. (Indeed, I've got a Schwinn Sierra that's about four years old, and I've been thinking of giving it a new coat of blue paint with yellow highlights. Unfortunately, I know I don't have the skill to make it look even halfway decent.)

Road bikes are, obviously, built specifically to ride on roads, and aren't suited for cross-country travel. The tires are very narrow to provide as little resistance as possible to the road, and the handlebars are of the drop-down type which force the rider to lean forward at an acute angle. However, there are various additions to the handlebars one can get so that when resting is more important than speed, it's possible to sit up straight and still control the bike properly.

Lowriders are another type of road bike, though not one used for racing, but rather for cruising around showing off their paint jobs.

Custom Built

What does custom-built mean? A custom-built bike is one that is built for you from the ground up - and hand-crafted more often than not. Your every measurement is taken and the frame is built to those measurements. Cranksets will fit your legs, top tubes will be just the right length, and it'll be built out of the space-age material you prefer.

And in addition to that of course you can choose the types of shifters and breaks you'd like as well.

Custom-built bikes are the most expensive bikes you can get, but they will fit you like a glove and if you are a serious bike rider that is the type of bike you'll want.

Serious road bikers have many different activities in which they can indulge, from"ultra long distance riding" (Randonneuring) to triathlons - where one of the three segments of the race is biking. These type of athletes have to have custom-built bikes.