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Re: The String Thing

FOG - last night I did the string thing with a laser as well as a string.

The laser that I have paints a vertical line.

I just had the laser knick the front and back edges of the rear tire, and it would paint a line forward, all the way past the front of the bike.

No real advantage, just another option.
 

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Yep, good Idea, I got me one O them laser things too. Never used it for a plumb line though, but it has that option.

On another list I used to dole out Smart pellets for a good Idea or correct answers. Like Pavlov.

That'en worth a food pellet.

FOG
 

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I for one normally simply trust the manufacturer's increment marks on the swingarm. I also normally trust the triple tree clamps are a flat plane so if the forks are adjusted to the same height on each side it is correct. However, I could see this as useful in making a minor adjustment to a bike that has been wrecked.
 

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Sorry Bud, but your wrong on both counts. Your Trust is misplaced. The Swing arm marks are often "Off" and even if they are correct it's much harder to be accurate with them. A tiny error that would be imposable to see can be magnified at the wheel. And the forks can be, and almost allways are, twisted. Even if the tube are level. The top tree can be misaligned Radially, with the bottom one so that the forks form a kind of Spiral. in this condition as well as binding the forks and aggravating the bushing wear you induce a kind of Bump steer that turns the wheel as the forks compress.
In almost every case I have checked, to achieve vertical alignment I've had to slip one fork tube up or down in the triples to get the front wheel parallel to the rear in the vertical plane.

Pleas read the instruction and do it correctly
 

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So I was doing a chain tensioning and decided to do a string alignment this time rather than using the factory marks. I am finding that the center stand is right in the path of the string on the right side of the bike.

Anyone else have this problem? Mine's an 06 if that matters. I will work on it some more tomorrow, it's possible the wheel is pointed way off to the right.
 

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I've been trying to cure a front wobble issue in my bike ('03) for a while now, and have gotten pretty adept at setting up "the string thing" that FOG described above. I know what you mean when you say some of the centerstand parts get in the way. You'll need to play around with the rear to front placement of the string, but the strings will definitely go from the rear to the front without touching anything else, including the center stand.

I ended up using fishing line (don't know the test poundage ;)) since its thin, round and can be "cinched up" really taught. I wrapped the string around the back of the rear tire (you'll need to experiment with the height on the tire, but go as high as possible without touching anything but the front edge of the rear tire), fished the line through the centerstand, then tied the line to two mini-sledge hammers which I placed about to feet in front of the front wheel. I fiddled with the placement of the hammers to make sure the line from the rear tire was as straight as possible without any deflection due to touching the front of the rear tire. You can follow the rest of FOG's instructions at this point and get the system to work.

If this setup is not correct, I'm 100% positive someone will jump in to let us both know. Keep working with the setup, it takes a little practice at first, but you'll get it.
 

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Close enough, but I wonder if you wouldn't be better able to gage the fron wheel if the front of the strings were a bit higher. Parallel to the floor at the same level as the rear would be Ideal.

Did you also do the vertical check too?

FOG
 

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Well, I found that if the rear wheel is aligned correctly the string on my bike is about 1/8" inch away from the right side of the center stand. So you have to start out either correct, or with the back wheel pointing to the left :)

I think I've got it aligned pretty well, the left / right side measurements on the front wheel were off by a little less than 1/16 after torquing the axle... well, at least as well as I can measure with a ruler and string :) Still need to clean the chain and put the plastic bits back on, then I can take it out for a test ride.

Some pictures of my setup, feel free to criticize: (These pictures might be down tonight, flickr is up for some scheduled maintenance here soon)



Not a whole lot of clearance here...


This was about as high as I could get the string without hitting the center stand on the right side.
 

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Looks exactly right to me in terms of the rough setup. FOG may be able to suggest additional minor tweaks to get the most accuracy out of the method, e.g. making sure your bike is exactly vertical in relation to the ground prior to setting up the horizontal string thing measurement.
 

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Went out for a brief ride to see how the alignment feels, didn't notice anything out of the ordinary although I only got up to 50 or so.

The factory alignment marks seem to be pretty good on mine, I used them to do the initial alignment and when I checked it with the strings it looked to be right on.
 

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Hey Slugger those Pictures Retsmah posted are perfect illustration of the string thing set up. If you could add them to my discription that would be super. Of coruse Give Retsma the Byline.

FOG
 
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retsmah said:
The factory alignment marks seem to be pretty good on mine, I used them to do the initial alignment and when I checked it with the strings it looked to be right on.
I gotta say I've had the exact same experience in my 23 years of riding. The factory alignment marks have always been spot on when I've checked them with several different alignment methods on various bikes. So, for the last 10 years or so I've never used anything but the factory marks.

Think about it.... In our litigiuos society, I can not believe the cycle manufacturers would allow the (very important) rear wheel alignment marks to be inaccurate. The liability would be far too great to allow it.
 

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ZEDhead said:
I gotta say I've had the exact same experience in my 23 years of riding. The factory alignment marks have always been spot on when I've checked them with several different alignment methods on various bikes. So, for the last 10 years or so I've never used anything but the factory marks.

Think about it.... In our litigiuos society, I can not believe the cycle manufacturers would allow the (very important) rear wheel alignment marks to be inaccurate. The liability would be far too great to allow it.
Methinks it wouldn't much matter from the liability standpoint. It really only rears it head when you take your hands off the bars and it's out of alignment but matched to the marks. When you start your description of the accident with, "I took my hands off the bar for just a second," it's a pretty sure bet that their liability stops there.
 
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Nick D said:
Methinks it wouldn't much matter from the liability standpoint. It really only rears it head when you take your hands off the bars and it's out of alignment but matched to the marks. When you start your description of the accident with, "I took my hands off the bar for just a second," it's a pretty sure bet that their liability stops there.
Nice catch-22 there. You think you notice it so you take your hands off the bars and confirm it, but without taking your hands off the bars it's impossible to confirm.
 

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The point of the string thing is to see actually what those Factory marks are supposed to do. It's like a Magnifying glass to help you see better. If you have read my little stories about gyros and wobbles, and you do the string thing you WILL better understand what make your motorcycle work.

If you don't CARE Shut up

Note to administration. Once a Item has been made a sticky it should be closed to further comment except through the Admin.
I understand them to be information not to be corrupted by inane useless commentary

FOG
 
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Then if you are going to do the string thing 100% properly to check the factory alignment marks...

You need to remove the rubber and align to the rims only. Did you ever notice how much runout there is on the tire sidewalls?

Try it. Put the bike on the center stand and rotate the rear wheel. Watch the side walls of the tires. They wobble don't they?

Seems to me way too much runout on the rubber to accurately measure alignment within a few millimeters at the ends of the string.

Just a few hundredths runout of the rear tire will be much greater at the front tire due to the string angle and distance.
 

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Yes this is true, But easy to check, just spin the tire and watch it. If it bad or your really anal. just adjust the strings bu measuring to the wheel rim.
You can also fit four small equal sized blocks of wood to the nice flat surface on the rims to space the strings out off the tire.

Good point thanks for ading it.

FOG
 
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FOG said:
You can also fit four small equal sized blocks of wood to the nice flat surface on the rims to space the strings out off the tire.
Now that's a good idea! Never thought of that. This way you get rid of the runout from the tire and get much more accurate measurements up front. They should measure to the front rim as well and not the front tire.

That's the problem.... I'm too anal! :D

Just a quick calculation:
assuming approx 17" across the rear tire where the string hits and approx. 4 feet to the front tire for one measurement...

With only 1mm (.04") of runout on the rubber the string will be off approx. .113" (almost 1/8 of an inch).

This dimension will only get larger as the 4 feet (assumed distance above) gets longer.

I know you already know this FOG, just pointing it out to the younger guys so thay can take this into consideration...
 
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