I looked at the website, but how does it work exactly? From the website it just looks like a ruler you place behind the front wheel.
Look at the website header. It shows how the fast the Proaligner works. The black center represents the width of the front tire. The gray background represents the width of the rear tire. When the front rear tire/wheel is in line with the front tire/wheel, the measurement on either side is equal.
If the wheels aren't aligned, the difference in dimensions on the scale on either side are different. Half of the difference tells you how much the rear wheel is offset. It's really simple and accurate to .050 inches.
The website explains all this. Detailed user instructions are on the back of the package and are available as a PDF printout. I haven't seen any instructions for aligning wheels printed on a roll of string.
I first saw the Proaligner being used at an AFM race. Racers don't align the rear axle to the swing arm pivot, because that's as unreliable as using swing arm marks for wheel alignment. For any serious rider who needs accurate steering and balanced handling, left and right, the wheels themselves have to be aligned.
You first align the front and rear wheels, before you check rear axle to pivot alignment. If the chain/belt prockets are out of alignment, it means either the swing arm or the frame is bent. If you ask the Frame Man, he'll tell you that simply aligning the sprockets is the same as riding with a crutch. The chain may run straighter, but the real problem isn't fixed, and you've still got a gimpy handling bike.
I'm having a hard time believing that your rear wheel was 3/4 an inch off if it was lined up on the OEM marks.
That's the reality. If the swing arm marks on either side of the rear axle are 9 inches apart, on a 57 inch wheelbase a swingarm mark only has to move .08 inches to produce a 3/4 inch mislignment. That's only three flats of the adjusting screw –if the swingarm marks are accurate to begin with.
I watched AFM#462 check the alignment on his GP250 Yamaha and find it was 1/2 inch off, when the factory swing arm marks indicated that it was dead nuts. He told me the Proaligner was indespensible. Even James Randolph AFM#2 uses it. That's good enough for me.
