A friend of mine is about to embark on his first bike build. He sent me a e-mail stating that he purchased a frame and needed help with "the rest". Since I felt that an in depth responded was warranted, I decided to put my recommendations here so that everyone on the dud dud dud had an opportunity to read them. Of course, my recommendations are often disagreed upon, and sometimes even by myself, so take it with a grain of sodium. Assuming that the frame he bought fits, has all the modern fittings, where do you go from here.
Sellers description, parred down to the useful stuff:"
Orbea Vitesse road bike. believe it is a 2002. The bottom bracket has English threads. Fork is an Easton EC90 Superlight needs a new upper headset bearing ; the lower bearing is there.
The next three steps are component selection, assembly, and fitment. In this article I will concentrate on component selection. You will be on your own for assembly, and I will lightly cover fitment since the frame fitment is the most in depth and already predetermined in this case.
The heart of a bikes components is the drive train. Everything thing else in one way or the other is related to this. The first thing I think should be decided upon is the crank. A few things should be now considered: triple or double, 9 or 10 speed, Bottom bracket, brand.
Triple or Double. Traditionally road bikes have two chainrings; double. However in more recent years a granny gear, or a third small chainring has become very popular; triple. The extra low gears allows steep hills to be climbed more easily. Sure there are ways to lower the gears on a double, such a lower tooth count on the second chainring, or a mountain bike/larger rear gears. However none of them do so as smoothly as having a third front gear. The two main determining factors when deciding between the two is how many/big are the hills you ride, and what kind of riding power do you generate. Events like the Death Ride and the Tour of the Rockies tend to lend itself to the use of triple. However to show up to a race event with that third ring will have you laughed out of the peloton. Deciding on a double or a triple might seem like a small issue and might not be the most important, however it should be considered early in the selection process, as other components such as derailleurs and shifters must be differentiated. Another factor to consider with the 2 vs 3 ring selection is cost. Road bike specific triples are a relatively modern thing. Where as I can get a 10 year old high end double, a good used triple might cost me a few more coins. Finally to throw another wrench in the mix is the compact double. These crank arms have smaller chainrings and thus also lowers your pedal generated top speed. Compact chainrings have a smaller bolt pattern, which limits the selection of chainrings as well.
Length- as a sub topic let's talk about length of the crank arms. The longer the arms to more torque. The faster the arms the quicker the acceleration. Mountain bikes usually use a longer crank verse a road bike. Uphiller: longer; flatland sprinter: shorter.
10 speed or 9. If you go out and buy a new crank, chances are it will be ten speed compatible. The 10 or 9 number refers to the number of gears in the rear, such that a triple 10 is a "30 speed". So why is this important when selecting front cranks. Since the hub spacing on the frames has been standardized, and the narrower the hub flanges the weaker the wheel, the only way you squeeze in that extra gear is to make everything thinner. Thus a 10 speed chain is more narrow that a 9. Though a 10 speed chainring will work with a 9 not all 9's will work with a 10. Most new road bikes come with a 10. Thus if you apply computer buying logic (buy the most up to date equipment so it does not become obsolete too soon) you will want a 10. Things to note is that used gear will be harder to come by in 10. Also due to the fact that everything is thinner means that it will wear out a bit faster. Is there any advantage to 10 over 9. You won't really notice the extra gear, but it does make hitting that right gear more likely. Of course this is not the end of it: 8 and 11. I would try to stay away from getting 8 speed stuff. Applying the same computer logic, it is harder to find replacement parts for 8s already. And know when to say enough. There are 11 speed drive trains out there. But who knows if that will last. 10 speed has been around for long enough that it is pretty standard.
If you have found the perfect crank and it doesn't have this type of BB, what type does it have ? The hollow Octolink cartridge style ones are ok. The square taper cartridge ones kindda suck though last forever. Crank bolts are better than nuts. And I will never hesitate to run an old school rebuildable. English threads are the most common, and you just have the measure the BB shell length of your frame in mm to size to spec. If you really want to get geeky with the old school stuff, you can spec and learn about other BB threads, various length of spindle, chainring, chain stay clearance, off set.

Hope you enjoyed reading Part 1, in road bike building. I'll let you digest that, while I cook up another plate 2.
Next time: derailleurs, shifters, gears and brakes.