A simple ruler that allows you to easily check the alignment of your motorcycle chain by assembling it to the sprocket (up or down) and checking the "D" along the ruler.

I made that because I don't appreciate the tools we can find online as they aren't practical nor precise and laser alignment tools are expensive as hell.

You just need to know the thickness of the sprocket to choose the right tool. You can then choose between a flat ruler or one with small "teeth" that make it easier to visualize the alignment.

I have taken into account the tolerances of the sprocket and average 3D printers, as well as phenomena like elephant foot. If your printer is properly calibrated, the ruler should fit perfectly without deviating by 1°.

Here is a quick guide to choose the good thickness (I asked exemples to chat GPT so I'm not 100% sure ^^") :

Chain pitch 420, 520 : 6mm
er6, cb500r, monster 821, R6, duke 390/125

Chain pitch 525, 428 : 7mm
CB650R, MT-09, 690 duke, zx-6R, ninja 400, R3

Chain pitch : 530,630 : 8,9mm
hypersport, high torque/engine bikes
Duke 990, S1000, ZX-10R, Africa twin

Please do not modify or sell them. If you need a modification, ask me directly.

Enjoy :)