From steel to carbon: the evolution of BMX bikes
The Schwinn Stingray bicycle, the bicycle that most kids used to imitate motocross in the early seventies, was made of pure steel. When kids started bombing down the hills it was clear that the Stingray didn't hold up. Since “real” motocross bikes had suspension, all kinds of bicycles were welded up by motocross companies in order to give the riders what they needed. These bikes usually weighed over 20 kilos but as long as the tracks were going downhill it didn't matter much. On flatter tracks these bikes could be ridden, but definitely required more force and power with every lap. The double diamond frame became a good base for a BMX bike. The tendency then moved to chromoly tubing, which was lighter and stronger than regular steel. Race Inc and SE Racing experimented early on with aluminium frames, and later the bikes moved from running coaster brakes to freewheels.
Looking back now at the bikes from the early eighties is amusing. The geometry wasn't right: the top tubes were short, the fork angles were raked and the seat posts were long. However, product development continued, with improvements leading to stronger, lighter bikes. Gone were mag wheels, front brakes and suspension forks. New frame models such as the HARO Monocoque, Gary Fisher and Trek Y frames or Powerlite P-61 Monocoque didn't last. Gimmicks such as the one-sided Kastan forks or Cannondale's Lefty forks didn't survive BMX. GT Bicycles tried to convince everyone that their thermo-plastic was the best material for a BMX bike, but that didn't start a new revolution either. Chromoly seemed to be the material of choice on the circuit but it was later replaced by aluminium, a material that is widely used among frame builders today. A great move forward are the headset cups integrated into the frames. Those who used to ride in the eighties will remember cracking a few of these steel cups. The A-head system is now being used on every bike and for good reason: it works. It's hard to believe today that BMX racers all used flat pedals during the first 25 years of the sport. Finding a bike with flat pedals in the pits will be hard nowadays.
Looking at the top-of-the-line bikes now we see more and more carbon fibre being used for frames, seat posts, rims, forks, and little details such as spacers. The material is light, stiff and strong, exactly what the riders want. With everyone training hard and the races often so close, details in the custom-built bike can make a small but valuable difference: special gearing, different crank lengths, oversized clamping area in the bars, disc brakes, longer rear ends, different tire pressure, a 5mm longer stem, tighter click pedals, oversized axles, titanium spokes… All are part of the fine tuning for the racers who line up on the start ramp. If your bike feels right you'll feel good. If you feel good you'll be faster. Let the development continue.