How to string align your rear wheel!!

FinalImpact

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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! :)
DSC_4255chainpattern.jpg



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.
06-DSC_4283.jpg


Rout it through like so!
01-DSC_4273.jpg


Avoid touching anything but the rear tire!
02-DSC_4270.jpg


Eagle Eye the string. Just BARELY touching the rear tires edge!
03-DSC_4274.jpg


Determine the distance to the front disc. Measure and compare to other side!
04-DSC_4272.jpg


The other side! These should be the same distance!
05-DSC_4277.jpg


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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FinalImpact

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IF you have a vibration complaint like the seat or the bars vibrate excessively while traveling at ANY SPEED, GET THE CHAIN ALIGNED PROPERLY!!!

My bike has always had a very tiny vibration in both the bars and butt and I figured this was normal for the I4 engine design! Guess what, after doing this, there is virtually NO vibrations in the Butt or Bars! I swear its like free horsepower too as the bike is SOOOOOOO smooth now!!!!

Because its so close to perfect right now, I see a laser light with a magnetic base (rear rotor) in our future so I can do this quick and easy on a fixed point and ditch the string!!!!
 
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FinalImpact

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I vote for Stickiness as I didn't see a how too when I was looking! :thumbup:
 

FinalImpact

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Thanks! I added some comments. . .

Nice write up!

May I suggest adding a few things before the "stickyness":

1: In my experience with this method, is it much easier if the loose ends of the string are attached to an inanimate object. I opted for two tool boxes. This ensures that the string does not move in your hand when measuring; or reversed; you don't move the string with your hand when measuring.

Agreed! If we get creative, there is usually something that could be used and I mention that in the text above. It's much easier with a fixed object holding it!
1 option could be: A chair leg itself. OR Picture this; a chair with a broom stick across its legs. Run the strings over the horizontal broom stick. Tie some weights to the strings for constant tension. Once at the right height, you just slide the string side to side to obtain proper contact with the rear tire. The weights hold the string taunt. Just an idea. . .


2: In order to be completely accurate, you should really measure to the lip of the rim; not the rotor. Something perceived as a "small" misalignment on the rotor measurement may go un-adjusted. For instance; 1° misalignment of the front wheel would only be a 1/8" difference at the rotor whereas it would be 3/8" at the rim lip. Which would you be more likely to ignore?

Also true! Just so everyone follows; Measurement error can be induced if the front wheels are turned! By measuring the leading and trailing edge of wheel to verify the distance is the same, it confirms the wheel is not turned.
I think a sketch/illustration would be worthy. . . If you want it dead on, do this! Otherwise accept that there will be some error and use the rotor just below the front axle.

Also, in the ideal world we would measure from the rear wheel and not the rear tire. But this requires some kind of spacer be made and held up to the wheel.

I think these repeat themselves....

3: When completing the measurement at the front wheel; you should also measure the distance from the string to the "front" part of the rim, and measure the distance from the string to the "rear" part of the rim. In a perfect world, all four measurements would be identical.

True!

Lastly - Some verify the final setup by measuring the swing arm pivot center to the rear axle center. This is a great way to confirm the alignment of the sprockets! And it "should be good enough!"

Now, assuming the bikes frame is square - using the string to the front tire looks at the big picture aligning the front and rear tires but it does not guarantee the sprockets are aligned.

Thanks for your input Skooter!
 

Black_Cirrus

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I did this on my old bike but with a twist. To be sure the front forks are true. Part of the alignment is to take a piece of plate glass 3" or so X wider than forks and rock across the forks to check for squareness like a unlevel chair. If you have ever let go of the bars going down the road and it starts to shake the forks are not straight in the triple tree. My favorite string holder is jackstands. There are great directions on ex-500.com but it wont let me look at it without logging in (that was an old password). Also you can use a plumb line to check for vertical alignment. All of these should be performed after a wreck to check for frame twist, more important on that bike with a steel frame that tends to bend unnoticeably.
 

FloppyRunner

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I dunno, when I tried this a while back I just got frustrated because I just couldn't seem to get it just right. My guess is that there are just too many variables. How close is the front sprocket to being 100% true? Is the bike on the centerstand? If so, the chain could be applying a force from only the LH side (the chain).

To accomplish what we want, the front and rear wheels will not only be pointing in the same direction but they will be in the same plane, and that seems to be outside of our control...

Or maybe I'm just making no sense...
 

Black_Cirrus

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I dunno, when I tried this a while back I just got frustrated because I just couldn't seem to get it just right. My guess is that there are just too many variables. How close is the front sprocket to being 100% true? Is the bike on the centerstand? If so, the chain could be applying a force from only the LH side (the chain).
the chains influence is minimal due to the slack and should be accounted for with the adjuster
To accomplish what we want, the front and rear wheels will not only be pointing in the same direction but they will be in the same plane, and that seems to be outside of our control...

Thats the job of the frame, swing arm and part of the reason why there is upper and lower triple tree clamps.
 

FinalImpact

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I dunno, when I tried this a while back I just got frustrated because I just couldn't seem to get it just right. My guess is that there are just too many variables. How close is the front sprocket to being 100% true? Is the bike on the centerstand? If so, the chain could be applying a force from only the LH side (the chain).

To accomplish what we want, the front and rear wheels will not only be pointing in the same direction but they will be in the same plane, and that seems to be outside of our control...

Or maybe I'm just making no sense...

Ditto to above - over complicated it;

1) Sprockets are not being checked here, but as seen in the picture, they can tell a story.
2) Center stand is a must but it could be done on a side stand but would be much easier if up right.
3) chain tension has no impact.
4) True - the front wheel does need to be pointed straight ahead. We can measure this if we take our time OR use a holding fixture for the strings. The rear wheel is what we are aligning. So it doesn't count per say. . .

Although the original post has allot of text, its only to help understand WHY we do this. Its not work just time consuming if you're used to gettting everything done in 10 minutes. . . chill and have a beer! Its going to take 20. lol
 

FinalImpact

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Some time down the road. . .

Here you can see the Original Pattern from me adjusting the chain and not doing the detailed work to align it. (ORIGINAL PICTURE FROM ABOVE)
DSC_4255chainpattern.jpg


VS this:
The contact patch is much closer to centered:

And the bike is Vibration free. . . .
DSC_5139RearWheelAlign.jpg

DSC_5136rearWheelAlign.jpg
 

Andz

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It obviously works for you so that's great.

Personally I prefer to get the tension of the chain right, measure the length of the tensioner bolt protruding from the rear of the swingarm and match it on the other side. Quick and easy.
 

Guitar Man

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I have always just made sure the marks were the same on each side and have never had a problem with tire wear. I think I will do the string method out of curiosity to see if it actually is on or not. I do seem to have a little vibration at a certain speed. Wondering if this will clear it up. I will update to let everyone know.

Those last comparison pictures really told the story. Good job.
 

Guitar Man

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So. I just went outside and checked mine and I was really surprised.

I strung it all up and did my measurements on the front rotors. I had 1/2" on the left side and 1 5/8" on the right side! It was way off. You didn't even have to measure it to know. I adjusted it with a little help from my daughter and now it's about 1" on both sides.

Here's a little added bonus. Checked how the wheel spun before and after. You could feel the resistance before and after that sucker spun with hardly any resistance!!

Also I've noticed that it gets a little squirrely in the corners sometimes. I'll bet that will go away as will the vibration that I've noticed. Can't wait to ride it to work in the morning.

Everyone should take a little extra time, have a beer or something and check it out. I think it will:

1. Save you gas.
2. Save wear and tear on your chain and sprockets.
3. Save wear on your tires.
4. Improve handling.

I'm confident that this is a good fix.

The moral of the story: "DON'T TRUST THE ALIGNMENT MARKS!!!!!"
 

Guitar Man

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Rode the bike to work and back today. I did feel a noticable difference in the bike. It seemed to roll smoother and shift easier even. It even seemed to accelarate a little easier and smoother like it wasn't fighting the added resistance. I had a vibration around 6500rpm that is no longer there. The only vibration now is the engine. Funny thing, my handle bars always seemed to look like they were a hair turned to the right. That went away, they are perfectly straight now.

This worked pretty damned good if you ask me. Worth doing for sure.
 

Cowboyx

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Okay new to the site and needed some help. Also had a few questions. I have a 2008 FZ6 and just did chain and sprockets. So did both sprockets got the chain on (first time) lots of lessons learned.

Questions:
1. Does the caliper method really work to align the rear tire?

2. How do measure the chain slack to make sure its correct.
 

FinalImpact

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Okay new to the site and needed some help. Also had a few questions. I have a 2008 FZ6 and just did chain and sprockets. So did both sprockets got the chain on (first time) lots of lessons learned.

Questions:
1. Does the caliper method really work to align the rear tire?

2. How do measure the chain slack to make sure its correct.

Hello and welcome to the sight. The owners manual has the setup for how to check the chain slack and you can see I opted for strings over the caliper viewing for setting the rear.

What I'm goin to do is suggest you pose your question over here and/or use the search function as much of this has been brought up before and answered. Garage / Mechanical Help - Yamaha FZ6 Forums - International FZ6 Motorcycle Community Forum and here: FZ6 Technical - Yamaha FZ6 Forums - International FZ6 Motorcycle Community Forum

The reason: this thread is on topic for those who wish to try and string align so feel free to copy and paste your question in the proper section...

Let us know if you need a service manual and its very likely someone will chime in.
 
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crazycd1

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Question for those who have used this method for rear wheel alignment.. How many marks on each side show after you were finished? I just did this and there is a difference of 1/2 way between two tall marks and that seems like a lot to me. Just wondering if I need to look for something else out of place that is causing the difference like the forks or something bent....
 
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