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Rear Wheel Alignment -- String method


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I had carefully adjusted my rear wheel alignment after adjusting the chain using the marks on the adjuster blocks and swingarm. For no particular reason, I decided to verify that it was perfectly aligned using the string method. Turns out it was off by about 1.5 cm as measured at the front wheel, using the string method.
 
The general idea is to wrap a string around the sides of the rear wheel and pull it forward so that is exactly aligned with the rear tire. Measure the distance from the string to the front wheel on both sides. it should be the same.
 
1) start by attaching a piece of string to the back tire. Rotate the tire so the string is near the bottom.
2) Attach the long ends of the string to something that you can move left/right to get it perfectly aligned with the rear tire, on each side, independently.
3) Measure the space from the string to the front wheel on both sides. We want it to be exactly the same.
4) Adjust the axel blocks to move the rear wheel angle left or right as needed. Re-align the strings. remeasure the space at the front wheel.
5) Repeat until the rear axel is just right.
 
Hints:
Start by loosening the rear axel nut. Stick a shop cloth between the chain and top of rear sprocket and rotate the wheel back to put tension on the chain and force the wheel against the axel adjuster blocks.
 
 
 
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Went for a 150 mile ride and could actually notice the improvement. Bike cornered better and felt much more neutral and willing to turn. 
 
[sorry about the dirty rear wheel. I've been riding some gravel roads lately. (Yes I know its not a DS bike, but it handles gravel and dirt just fine within it's limitations. I have a "real" DS bike (KTM 690 Enduro R ABS) that I use in more challenging places.]
 
 
 
2015 FJ-09, 2016 1290 Super Duke, 2017 150 XC-W (primary ride), 2012 DR650
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Get a set of these and never guess or worry again if the alinement is right.
Have you verified that the alignment is close with them? What is the tolerance? 
I stopped at 1mm differnce, slightly less than the width of the nylon string I was using.
2015 FJ-09, 2016 1290 Super Duke, 2017 150 XC-W (primary ride), 2012 DR650
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A while back, I made an alignment tool. I used it on the FJ prior to checking with the string. Thought it was dead on. It was not.
 
The precision of the string method far surpasses the accuracy of the measurement from swing arm pivot to axel bolt.
 
 
 
The home made tool is set to the length on one side, then the adjuster blocks are moved to get the same distance on the other side.
 
swing arm bolt measurement point
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Rear axel measurement point. Tool is adjusted to match the length on one side, then the other side of the axel is adjusted to match the tool setting.
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Tool
 
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2015 FJ-09, 2016 1290 Super Duke, 2017 150 XC-W (primary ride), 2012 DR650
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  • 2 years later...
Interesting recent "MC Garage/motorcyclist.com" video on rear wheel alignment: they suggested the traditional string method LAST in their suggested methods, saying it's complicated and prone to user error compared to the other methods (Motion Pro tool, or axle-to-rear wheel axle methods.)
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I use a Motion Pro alignment tool. Cheap and easy... ensures sprocket is aligned with chain run. 
172305d1262995194-rear-wheel-alignment-align-430x315.jpg?iact=hc&vpx=662&vpy=140&hovh=192&hovw=262&tx=86&ty=92&sig=106202286686398019767&ei=z0EtUN_2MqaI6AHIjoHADA&page=12&tbnh=145&tbnw=192&start=161&ndsp=15&ved=1t:429,r:8,s:161,i:279
 
http://www.motionpro.com/motorcycle/partno/08-0048/
I have this too. Not my favorite type of tool because it relies on you sighting down it straight which I always second guess. That said, it gets the job done. I just wish the metal rod was longer for a more accurate reading. 
 
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