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The apple of discord and chain alignment.( A review of the Profi laser chain alignment tool)

Submitted by monkey on Sun, 20/09/2020 - 8:38pm

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Was it the feeling that I never quite got my chain alignment right, or the recent phenomena where right handers suddenly seemed easier than the left, or was it the was boredom of the lock down? Probably the later but the magnetic, chain alignment tool, promising laser precision, was too irresistible. A pocket sized gadget I had to have.

Chain alignment is a pain for me in more ways than one given my gravel drive way. 10 minutes on my hands and knees and I’d wished it was a shaft drive.
Ok, up on the paddock stand, loosen rear wheel, position magnetic alignment tool to rear cog. Turn on laser light and sure enough my suspicions were confirmed. The red laser light drew a line on the chain but veering off to the side. Ok, adjust alignment. Great, a red laser line running precisely along the top of the outer links just like the pictures. Now, how are those marks on the swing arm? Bugger, they are way out! Now the dilemma. Which is correct?

I consult “You Tube”. A guy there has this string method wrapped around the back wheel and brought up on each side to the front wheel, the string ends tied to a couple of bottles of oil as anchors. He spends an eternity lining up the string, moving the bottle, checking the string alignment, moving the bottle…. and just like him I do too, much to my discomfort on the gravel. In the end the string is 5 cms away from my front wheel on the left and 2 cm on the right. It’s out of alignment. I adjust the back wheel so the swing-arm marks line up better but for the life of me I really cannot tell if they are exactly equal. The strings seem to be about the same either side of the front wheel, about 3cm which is reassuring. What is the laser tool say now? It’s off alignment, “Hold on” it’s not sitting properly. Shining a torch on the rear cog there is a smear of grease. Just the slightest imperfection seems to throw the laser beam off. I meticulously clean the cog and attach the laser tool. Actually, that is not too bad. The line runs down the top of the outer link but through a cut-out over the front cog I can see the laser beam is sitting on the seal between the outer and inner link, just the slightest bit out. But hey presto, torqueing up the axle somehow lines up the laser line perfectly. I feel better now

Do I recommend this tool? Well according to a well-respected mechanic, the rear wheel has to be quite a bit out before it affects the handling, but for a neurotic like myself I just find it reassuring. If you ever do use one, ensure the rear cog surface is absolutely free of any imperfections.
Looking forward to seeing how it goes November – December. Cheers.