Admin
04-06-2001, 06:21 PM
Wheel Alignment: Avoiding The Crab Walk
Motorcycles are by definition single-track vehicles, so it's no surprise that their performance improves when the rear wheel directly follows the front. If you've got a shaft-drive bike, stop here and worry about something else for a while. For most chain-drive bikes-excluding models with single-sided swingarms or eccentric axle adjusters-there's a strong possibility that the wheels aren't in alignment. Why? If you or the guy setting up your bike used the stamped alignment marks on the swingarm, you've found the first clue(1). these marks can be notoriously inaccurate. Plus the gradients are too coarse to allow for precise alignment even if the marks are spot-on.
http://www.gixxer.com/images/align1.jpg
So how can you check your bike? It's easy. Put the bike on the centerstand or track stand and find yourself a length of twine, string or thin wire about two and ahalf times as long as the bike's wheelbase - 12 feet oughta do it. Find the center of the length of twine and wrap it once around the forward part of the front tire below the axle. Bring the string to the back of the bike underneath the stands. Look to see that the front tire is a straight as possible by centering the bars with reference to the gas tank or fairing. Now, here's the fun part. Lay yourself right down on the ground and grab the ends of the string(2).
http://www.gixxer.com/images/align2.jpg
Pull the sides taught against the front tire's sidewalls and sight along it. Because the rear wheel is is most likely wider than the front wheel, the string will no touch the front tire sidewall nearest the engine; instead check that the front tire is pointing directly forward by noting equal gaps between the string and the sidewalls. That done, pull the string to the forward sidewalls on the rear wheel until it is just touching. You should be able to sight along the string and see that the gaps at the rearmost portion of the front wheel are equal. Now see how the gaps at the aft part of the rear wheel work out(3).
http://www.gixxer.com/images/align3.jpg
Equal gaps left to right indicate that the wheel is properly aligned. More gap on the left side, for example, means the rear wheel is cocked leading-edge left, Make a small change to one adjuster (don't move them both) and see how the gaps look(4). Once you've got the rear wheel aligned, make chain adjustments by moving the setscrews an equal number of flats; this works amazingly well to keep the wheels aligned.
http://www.gixxer.com/images/align4.jpg
Motor Cyclist July 2000
------------------
Motorcycles are by definition single-track vehicles, so it's no surprise that their performance improves when the rear wheel directly follows the front. If you've got a shaft-drive bike, stop here and worry about something else for a while. For most chain-drive bikes-excluding models with single-sided swingarms or eccentric axle adjusters-there's a strong possibility that the wheels aren't in alignment. Why? If you or the guy setting up your bike used the stamped alignment marks on the swingarm, you've found the first clue(1). these marks can be notoriously inaccurate. Plus the gradients are too coarse to allow for precise alignment even if the marks are spot-on.
http://www.gixxer.com/images/align1.jpg
So how can you check your bike? It's easy. Put the bike on the centerstand or track stand and find yourself a length of twine, string or thin wire about two and ahalf times as long as the bike's wheelbase - 12 feet oughta do it. Find the center of the length of twine and wrap it once around the forward part of the front tire below the axle. Bring the string to the back of the bike underneath the stands. Look to see that the front tire is a straight as possible by centering the bars with reference to the gas tank or fairing. Now, here's the fun part. Lay yourself right down on the ground and grab the ends of the string(2).
http://www.gixxer.com/images/align2.jpg
Pull the sides taught against the front tire's sidewalls and sight along it. Because the rear wheel is is most likely wider than the front wheel, the string will no touch the front tire sidewall nearest the engine; instead check that the front tire is pointing directly forward by noting equal gaps between the string and the sidewalls. That done, pull the string to the forward sidewalls on the rear wheel until it is just touching. You should be able to sight along the string and see that the gaps at the rearmost portion of the front wheel are equal. Now see how the gaps at the aft part of the rear wheel work out(3).
http://www.gixxer.com/images/align3.jpg
Equal gaps left to right indicate that the wheel is properly aligned. More gap on the left side, for example, means the rear wheel is cocked leading-edge left, Make a small change to one adjuster (don't move them both) and see how the gaps look(4). Once you've got the rear wheel aligned, make chain adjustments by moving the setscrews an equal number of flats; this works amazingly well to keep the wheels aligned.
http://www.gixxer.com/images/align4.jpg
Motor Cyclist July 2000
------------------