The BMX bike comes in two basic flavors: freestyle and race. The freestyle (aka park) bike is made for the doing tricks and hard riding at the skatepark or on the streets. It’s an all-around bike. The race bike is made for speed and handling to swiftly get around the racetrack. It’s specialized. Both are single speed and geared for acceleration. Want more speed? Pedal faster. There is no next gear. Freestyle bikes use steel and heavy-duty components and in general aren’t as concerned with each gram of weight. Race bikes use aluminum, or carbon fiber, and lightweight is of great concern. They also use different geometries. Geometry for bikes is the angles and lengths of the pieces that make up the frame. These angles determine the handling qualities of a bike.
Let’s keep it simple for now. Back in the 70’s, 80’s, and early 90’s the BMX bike didn't have the variety of today. The majority of them were chromoly steel (cro-mo). They all looked the same. More or less, they rode the same way too. As the 90’s dawned the mountain bike took over in popularity and BMX began to wane. BMX began evolving and so did the bikes. Jumping milk crates and chasing one another on rough dirt tracks began to give way to X-Games style stunts and purposefully designed racetracks. This led to changes in BMX bike design to maximize performance for it's respective use.
Note that many of the BMX-style bikes at department stores are not meant for racing or serious tricks. The department store bike is great for sidewalks and getting around a campground or neighborhood. Or riding off a pier into the lake. And finally, the department store bike usually becomes scrap metal since the repair cost can exceeds the purchase price of a new one. If you or your kids plan to start racing or freestyling as a sport don’t rush out to buy a bike. Watch YouTube. Consult with the parents and riders at the track or skatepark. Send Beck Bros a message for advice. But whatever bike you get, make sure to ride it. That is what builds skill and confidence.