Pro Stock Motorcycle is a NHRA drag racing class that is the two-wheeled equivalent of the NHRA Pro Stock auto class. It has been a feature of NHRA since the 1980s, when it was added to the professional class structure and has since spread around the world.
For years, the class has been dominated by inline-4 cylinder Suzuki-based motorcycles, equipped with high-performance fuel and turbo chargers. Recently, however, Harley-Davidson V-twin machines have become more competitive due to favorable rule changes. The frames of a Pro Stock motorcycle are purpose-built specifically for drag racing and are not based on their street-legal counterparts like Pro Stock cars.
The Pro Stock bike chassis is adjustable for wheelbases between 68 and 70 inches. The long “4130” chromoly frame has no rear suspension but the front end features a modern "upside-down" telescopic fork with the larger-diameter outer tubes located on top for increased stability. During a pass, the rider shifts the five-speed transmission with an air shifter, which is activated by a small handlebar-mounted button. An air ram powers the transmission into the next gear. The rider is connected to the motorcycle “life line,” which, when disconnected, will completely shut the bike down and let it coast to a full stop. This is an important safety feature in case the rider needs to get off the bike for some reason while it is in motion.
Since the rear tire of a Pro Stock motorcycle is the equivalent width of a regular automobile racing tire, the bike is very stable. There is an on-board race pack computer monitor that monitors and adjusts critical engine functions, such as engine rpm, wheel speed, air/fuel mixture and exhaust-gas temperature. This information is downloaded to a computer inside the race transporter, or “team trailer,” after the race and is reviewed to help mechanics make adjustments to improve performance on the bike’s next pass.
There is also a lengthy aluminum "wheelie bar" that stretches 130 inches beyond the rear axle and keeps the powerful bike from flipping over backwards at launch. These bikes generate enough power to race the quarter mile on only the rear tire while the wheelie bar keeps the bike upright.
Racing motorcycles is difficult. The most important factor is weight, so drivers are usually women or smaller men, many weighing in around 100 pounds. Women drivers certainly give the male riders a run for their money and, a lot of times, are the victor in Pro Stock Motorcycle racing.
This is an exciting class to watch, as it can get kind of “squirrely” out there on the track. If you are looking for something different in NHRA, have a look at Pro Stock Motorcycle.
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