In this thread we are going to go over all the do's and don'ts when it comes to purchasing a new complete bike. After reading this, you will be equipped with all the knowledge necessary to pick out your own new BMX Bike!
First and fore most, we wouldn't recommend spending money on a bike unless it includes at least the following essentials;
Full-Chromoly Frame, Forks, & Handlebars
Other options include Hi-Tensil Steel parts which are renound for breaking very easily. It's better to spend the extra $100 or so for the Chromoly model than to spend $400+ on a new frame set when the Hi-Tensil gives out. Also be mindful that some frames and forks are half-Chromoly and half-Hi-Tensil, which is just as bad as full-Hi-Tensil.
These are rather critical because the hubs on your BMX will require more maintenance than most other parts. Opening up a hub full of loose-ball bearings is not only a hassle, but a sure-fire way to lose essential pieces of the hub. "Semi-Sealed" is NOT the same as Sealed. Sealed bearings are easier to maintain, require less maintenance, and are easy to find replacements for, all while spinning noticeably smoother. Also, aftermarket hub sets are $200+, so they're not something you want to replace shortly after purchasing a bike.
3-Piece or 2-Piece Cranks
Most bikes will come with 3pc cranks, and some may even come with 2pc or 2.5pc. Both options are essentially the same, with a main bottom bracket spindle and tubular Chromoly crank arms. This design is far superior, and easier to work on, than a 1pc crank set. 1pc crank sets are notorious for bending and snapping after short periods of time, and in order to upgrade to a 3pc/2pc from 1pc, you will have to buy a new bottom bracket ($20-30) aswell as the crank set ($75-150+)
These are mostly essential in the rear wheel since it will likely see the most abuse, but generally a good bike will come with Double-Wall Rims front and back. These are far stiffer & stronger than single wall rims. They are less likely to be dented or flat-spotted, or worse. & for the most part they will keep you from needing to have your wheel trued (straightened) every other week, which is very costly if you can't do it yourself.
These are all things considered to be essential when purchasing a bike, due to a strength-to-cost ratio.
There are also many cheaper parts on the bike that might not matter as much to a beginner or someone buying a complete on a budget. This is a list of parts and specs that are less important, & are easier and cheaper to upgrade over time or as things break;
You will typically see two kinds of headsets on a BMX, Standard & Integrated.
Typically, you will want an integrated headset, as this means that the Frame is equipped with sealed headset bearings & is a sign of quality.
However, if you do have a standard headset (with pressed in bearing cups,) you can buy an STI (Standard-To-Integrated) adapter to run sealed integrated bearings without any loss in strength or function.
Mid or Spanish Bottom Bracket
Quite similar to the headset, bikes will come with one of 3 options for bottom brackets. American, which typically utilizes a threaded spindle, removable bearings cups, and loose-ball bearings. Mid size, which is the most common and uses 2 sealed bearings that press directly into the frame. & lastly, Spanish, which is pretty uncommon, but is essentially the same as a Mid BB.
If you happen to have an unsealed American bottom bracket, you can insert sealed bearings by purchasing and American-To-Mid Bottom Bracket. This will require 2, 2.5, or 3pc cranks and an unthreaded spindle (if you already have 3pc cranks with a threaded spindle, you can purchase just an 8spline spindle.)