Motorcycle Wheels Technical Guide.

However, there are solid reasons why factory teams run high-quality custom motorcycle rims on their machines.

Probably the most important reason for choosing a high-quality pair of custom motocross wheels is the performance advantages these designs often provide. Motorcycle rims alone can weigh an average of four pounds (not including hub, rotors, spokes). The performance advantage comes from weight savings by using a superior design combined with higher quality materials. One must remember that weight in the wheel set is considered "Rotating Unsprung Mass" which is very detrimental to horsepower. Some custom dirt bike rims alone can save as much as 1/2 pound in this area. This savings not only has advantages from an acceleration standpoint, but provides great benefits to overall suspension performance of the machine as well.

Another important aspect which few motocross racers consider when choosing custom wheels is Safety. If you think about it, during race conditions your life may very well depend upon the structural integrity of these critical components. DO NOT use wheel sets or motorcycle rims if the country and manufacturer are not properly listed. All reputable firms will proudly list their name and country of origin. Most Asian motorcycle rims use various grades of 7000 Series Aluminum Alloys.

Excel and D.I.D. motorcycle rims are excellent and are made in Japan. Sun Rims is another excellent source and are made from 6061 Aluminum Alloy manufactured in California, USA.

A third aspect to consider is overall quality and construction of the wheel sets. A custom pair of wheels can contribute to a large portion of the overall machines cost. As a purchaser you should expect the highest quality for your dollars. Some manufacturers go to great detail to utilize manufacturing processes which yield the highest quality components. Manufacturers such as Sun use a machine-finished process which turns the motorcycle rims in a lathe after welding, which provides the truest rims with the least amount of runout (within 1/64th of an inch). Most production line rims are not machined finished. Also there are important structural differences on how the spokes interface with the rim as during use cracking often occurs in this area. Most manufacturers of motorcycle rims simply form a dimple in the drop channel, however some manufacturers go through a more elaborate machining process of step-drilling the nipple hole while simultaneously machining a precision seat for the nipple head to interface with. These extra machining processes create a more precise interface and helps reduce the tendency of the spokes loosening during use.

Once you have made your purchase, perform the proper maintenance to ensure your motorcycle wheel set lasts. Most popular causes of rim damage can be avoided by maintaining proper spoke tension. The spokes are tensioned fasteners, and will loose their tension with use due to the tendency of the spoke nipple seating into the rim and the spoke head seating into the hub. This seating will make the spokes loose in tension, and if you don't keep the spokes tension equal the rim will go out of round. New wheels take about two hours of ride time to break in, and spoke tension should be checked often during this time period. Once the wheels are broken in, check the spoke tension approximately every three hours of ride time.

Speaking of spoke tension, most people over-tighten the spokes. If you don't know much about motorcycle wheels you need to invest in a high quality spoke wrench. The wheels come relatively true from the factory, so as the spokes loosen, their trueness is best maintained by tightening each spoke a quarter-turn at a time on every third spoke. After three rotations of the wheel every spoke will be equally tensioned. This tightening procedure helps ensure you don't pull the wheel out of alignment.

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