After a 200 mile ride I saw a consistent contact pattern on my chain rollers that indicated the rear wheel was not centered as perfect as I thought it was (see picture below). According to the contact pattern on the chain, it showed that there was not equal loading across rollers surface. This made me question if the rear wheel was aligned properly. Previously I'd used the hash marks at the adjuster and some veneer calipers to measure from the wheels edge to the swing arm on both sides. The marks were on and the calipers showed an equal distance to the swing arm. Sadly, this doesn't mean the wheel is aligned to the bikes frame and front wheel.
There is an explanation for the pattern shown. Because the chain pulls from the top of the rear sprocket and the greater contact patch is on the left outer edge, it implies the rear hub may be turned to the right. Because I'd taken a good deal of time to get it right the last time, I needed another way to verify if the rear wheel was aligned to the chassis properly.
Dirty chains tell stories!
HOW TO STRING ALIGN YOUR REAR WHEEL!!
- Also, depending upon your Rear Tires Tread Design; pick equal grovers, valleys, depressions and/or bumps to route your string through on both the back and front of the tire. This string is acting as a straight edge so pick symmetrical points to measure from on both sides or your results will be off!!!
Tape the string to the tire like so! Hint - blind cord is thick and white, easy to see and handle.
Rout it through like so!
Avoid touching anything but the rear tire!
Eagle Eye the string. Just BARELY touching the rear tires edge!
Determine the distance to the front disc. Measure and compare to other side!
The other side! These should be the same distance!
Bottom line: the hash-marks will get within a 2~4 degrees of dead ahead. A tiny movement of less than 1/2 the width of a hash-mark can be a couple of degrees. In my book, its worth it to take a few extra minutes and dial it in.
- Example: My bike had twice the gap on the right side as it did the left. This means the rear tire was pointed to the right and needs to be shifted left a very small amount. Doing the math on this I had an angle of 1.01 degrees offset while still being perfect on the hash-marks. Sadness -> Lets say that angle was projected for 1 mile. How far would away would my rear tire be if allowed to follow its own path? 93 Feet! Any chance that would make my front tire wear funny? Yea, likely it would!
It was hard to get the camera angle the same to show the equal distance at the front discs but this gives you a general idea of how to string it. Just don't allow the string to bend around the tire as that is NOT a Straight Line and it will not give you proper results.
FYI: with the stock OEM rear tire, the distance from the rotors to the string was 1.100" on my 2008 FZ6
Hey, NASCAR does this for cars that go 200mph. It'll work on you're FZ too!
UPDATE 2012-07-06: http://www.600riders.com/forum/how-tos/45292-keep-simple-chain-adjustment-made-easy.html USE THIS to quickly adjust the chain slack without having to Re-String the chassis. Very Simple!
I hope this helps some of you!
Oh and money has it, my front tire won't scallop or razor on the left side again making the saw blade feel when you run your hand against the direction of rotation when the bikes thrust angle is Zero!
{Some say its the road crown, but you all check your bike and tell me the rear thrust angle is perfect before you ever mention road crown causing this and I'll report back now that I verified the angle to be near Zero}.
There is an explanation for the pattern shown. Because the chain pulls from the top of the rear sprocket and the greater contact patch is on the left outer edge, it implies the rear hub may be turned to the right. Because I'd taken a good deal of time to get it right the last time, I needed another way to verify if the rear wheel was aligned to the chassis properly.
Dirty chains tell stories!
HOW TO STRING ALIGN YOUR REAR WHEEL!!
- You need tape, A piece of string twice as long as the bike, and ruler/tape measure or set of veneer calipers.
- Center stand the bike and point the front wheel dead ahead.
- From the seat and the front of the bike, confirm the bars and head are straight.
- With a large chunk of tape, find the center of your string and tape the string to the rear tire at about 5-O'clock position as viewed from the right side of the bike. The string will go around the back of the tire and both ends will head to the front of the bike through the center stand.
- Now pull the string towards the bikes front disc (rotor) avoiding touching the center stand (rotate rear wheel to achieve a nice working height). The goal here is to watch the string as it just "barely" touches the leading edge of the rear tire. Do this by moving the string closer and further from the front disc and just as the string touches the leading edge of the tire, you have a straight line revealing the thrust angle of the rear tire.
- Notice the distance between the disc and the string. Measure the distance and write it down on paper. If you have veneer calipers, flip them over and use the long slide to measure with.
- Repeat on the other side and compare the values recorded
- Hint: When holding the sting taunt, flick it with you finger. If the long section ahead of the rear tire vibrates but the section within the tires rim does not, you likely have the string too close and are bending it slightly. Pull the string outward away from the bike and flick it again. You want to just barely make contact but not so much as to bend the string around the tires edge.
- If the rear wheel is properly centered, the strings distance from the front wheels discs will be the same on both sides. Take your measurement directly under the Axle bolt. This way if the head is turned a small amount it will have the least effect on your measurement. Take three readings on each side to confirm you get the same value each time!
- If the two sides show a different distance, loosen the axle nut and make a small adjustment until chain has the proper slack AND the angle is corrected. Tighten the axle nut!
- A greater value on the right means you need to move the rear wheel left. A greater value on the left, means you need to move the rear wheel right. The width of one hash mark is allot. A minor adjust of 1/2 the width of the hash mark can make a change of an 1" (inch) at the front wheel 56 inches away!
- Once adjusted, Repeat string measurement being certain to center the bars again!!! Confirm the distance is equal when measured under the front axle bolt. If it is, your work is done! Double check your work and be done!
- - Lastly; you can use a longer string and fix the ends to a heavy yet easily movable objects in front of the bike. Remember you'll need to be able to adjust the height, width, and tension with some degree of precision. Rotate the rear tire as needed to avoid the center stand and hoses under the bike.
- Also, depending upon your Rear Tires Tread Design; pick equal grovers, valleys, depressions and/or bumps to route your string through on both the back and front of the tire. This string is acting as a straight edge so pick symmetrical points to measure from on both sides or your results will be off!!!
Tape the string to the tire like so! Hint - blind cord is thick and white, easy to see and handle.
Rout it through like so!
Avoid touching anything but the rear tire!
Eagle Eye the string. Just BARELY touching the rear tires edge!
Determine the distance to the front disc. Measure and compare to other side!
The other side! These should be the same distance!
Bottom line: the hash-marks will get within a 2~4 degrees of dead ahead. A tiny movement of less than 1/2 the width of a hash-mark can be a couple of degrees. In my book, its worth it to take a few extra minutes and dial it in.
- Example: My bike had twice the gap on the right side as it did the left. This means the rear tire was pointed to the right and needs to be shifted left a very small amount. Doing the math on this I had an angle of 1.01 degrees offset while still being perfect on the hash-marks. Sadness -> Lets say that angle was projected for 1 mile. How far would away would my rear tire be if allowed to follow its own path? 93 Feet! Any chance that would make my front tire wear funny? Yea, likely it would!
It was hard to get the camera angle the same to show the equal distance at the front discs but this gives you a general idea of how to string it. Just don't allow the string to bend around the tire as that is NOT a Straight Line and it will not give you proper results.
FYI: with the stock OEM rear tire, the distance from the rotors to the string was 1.100" on my 2008 FZ6
Hey, NASCAR does this for cars that go 200mph. It'll work on you're FZ too!
UPDATE 2012-07-06: http://www.600riders.com/forum/how-tos/45292-keep-simple-chain-adjustment-made-easy.html USE THIS to quickly adjust the chain slack without having to Re-String the chassis. Very Simple!
I hope this helps some of you!
Oh and money has it, my front tire won't scallop or razor on the left side again making the saw blade feel when you run your hand against the direction of rotation when the bikes thrust angle is Zero!
{Some say its the road crown, but you all check your bike and tell me the rear thrust angle is perfect before you ever mention road crown causing this and I'll report back now that I verified the angle to be near Zero}.
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