A BMX frame is more than just a frame
Choosing the right BMX frame size is actually mostly based on personal preferences. There are a few pointers that can help you, if you are a beginner and haven’t obtained experience enough to have an opinion about the frame size. A rule of thumb is, that a shorter top tube length equals a more responsive BMX bike, while a longer top tube offers a more controlled frame.
Should my headtube angle be steep or flat?
The headtube angle also plays a big factor in the responsiveness of the Freestyle BMX bike. A steep headtube angle calls for a shorter wheelbase, this can make turns sharper. A lot of park and street riders prefer a steep angle of the headtube. The flatter angle is usually preferred by trail riders because it gives a better control at high speed.
What about Chainstay length?
When talking about responsiveness of the freestyle BMX frame, the chainstay length (the rear end of the BMX frame) is a great factor. The chainstay length typically varies from 12 to 14 inches depending on the frame. Most trail riders prefer a longer rear end since it's more controlled. Park/street riders often prefer a shorter rear end to give them a more responsive bike for fast spins and sharp turns.
To sum the toptube, headtube and chainstay talk up: If you are a park or street rider, you probably want a frame with a short top tube, a steep angle on the headtube and a pretty short rear end. If you are a trail rider you probably want just the opposite, but again - it's primarily about your personal preference.
Hi-ten steel vs. Chromoly
The material of the BMX frame for a freestyle BMX bike is typically hi-ten steel or a combination of chromoly and hi-ten steel. These materials are heavy, however, at the same time, they are extremely durable, which is an advantage when you perform stunts.
Most freestyle BMX frames are produced in hi-ten steel tubing. In order to provide more hardness for the hi-ten steel, in some cases manufacturers’ add chromoly. The freestyle BMX frames material will be stated in the specifications. Frames with chromoly will be called chromoly, others will be called hi-ten.