The most important thing is not to just blindly guess about alignment. Simply because you successfully mounted your sprockets and correctly connected the chain around them does not mean its "Miller Time." It is very important that you verify that the front sprocket and rear sprocket are parallel and in the same plane with each other. That failing, the chain will run off at an angle from the sprocket teeth. The consequences of this misalignment are substantial and few people realize the implications of even a small angular divergence.
What Does Misalignment Cost? Much has been written about, and most people are aware of, the premature wear and performance problems associated with the tires on their vehicles when they are out of alignment. Lots of complex equipment exists at the auto shop to identify and correct misalignment. However, when it comes to a chain and sprocket drive system, almost nothing has been published giving the owner/mechanic a true understanding of the importance of alignment, much less how to do it. Dyno studies performed back in the 70's confirmed substantial power losses (up to 4.75 horsepower on a 400cc machine) with sprocket/chain misalignment of as little as 8.5 degrees. These tests also verified that the wear rate on the sprockets triples, chain failures on these vehicles went up 35% and derailments were twice as likely. When you consider that an owner may spend $500 or more on an accessory pipe that yields a 3 horsepower increase, it would be madness to give it all back because the drive system was not aligned. Simply put, it is very costly to neglect accurate alignment.
Typical Alignment Techniques Most people just eyeball the chain alignment as best they can, guess that it's close enough and then forget it. Some think it doesn't matter at all. Most people don't have any idea that a simple method exists. All three groups are wrong. (The eyeball guys) can give it their best shot and still almost always end up from 4 to 10 degrees off, resulting in measurable power loss and excessive wear. The second group is ignorant. The third group is uniformed.
One tedious method is measuring the distance from the center of the swingarm bolt to the center of the rear axle on both sides and insuring the measurements are equal. Some cumbersome gauges were constructed with sliding/locking bars and pins to accomplish this (I designed and used one in the early 1980's). It is cumbersome to use, far from being universal and very time consuming. Another idea is to use a long, solid straight-edge between the two sprocket faces to detect any non-parallelism. This method is awkward and sometimes impossible because of physical interferences with other components in the way (i.e. swingarm attach points, levers, rollers, etc.).
The eyeball guys are actually on the right track but one key element prevents them from getting consistent perfect alignmenta reliable frame of reference. The unaided eye is doomed to guesswork.
Help is here for Group 1 and Group 3 rider/mechanics. Group 2 boneheads need an attitude adjustment first. An elegant solution is now available that guarantees perfect chain and sprocket alignment consistently. This new tool is an alignment gauge that quickly clamps to the faces of the rear sprocket in a matter of seconds. The simple fixture is absolutely parallel to the rear sprocket faces and extending 90 degrees from it is what I call, for the "eyeball guys," the missing linka sight rod that points along the top row of the chain as it proceeds toward the front sprocket. With this visual reference line, even a guy with 20/60 vision could recognize any divergence and adjust the axle blocks to bring the chain into perfect alignment with the sprockets. ATV guys will have a more involved problem since any run out will require an inspection or replacement of swing arm or rear axle carrier bearings, but at least they are cognizant of the problem.
It's Called the "Sidewinder Straightaway." This gizmo should be available from finer dealers and performance oriented shops. You can also check out this tool at http://sidewindersprockets.com "You Should Have Known"
Vic Krause Dirt Bike Magazine Midwest editor for 7 years; Original creator of the "Mr. Know It All" technical column; Bachelor of Science, University of Detroit; Master of Engineering, IIT. Raced 250cc and 500cc amateur motocross for ten years, Produced, popular, ive, mechanics seminars throughout the United States. Awarded several U.S. patents for innovations in drive system technology. Vic established Krause Racing when motocross started in the USA (1968).Owner of Krause Racing’s Sidewinder Sprockets Inc. http://sidewindersprockets.com .
Although, I am not much into bikes, bicycles, or any other thing that has chains and sprockets--but I do drive a car and understand the importance of alignment. This is a well-written and very informative article. Should be lots of help to bikers and cyclists.
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