Originally Posted by
Rogerogeroge
Don't compensate for incorrect pad adjustment by adjusting the spring tension on one side. That should almost be a last resort. First, make sure the brakes are set up symmetrically as I first described. No need to start by taking everything apart if it's not crusted in dirt and corrosion. Also, ideally you should use the hole in the brake bosses that produce the least spring tension - although it's common practice to use the middle hole which makes it easiest to add or subtract spring tension from either side.
What? The spring tension adjusting screws are there to fine tune different for differing spring tension. This is the method done hundreds of times a day in hundreds of shops and at home all the time. I do agree that in a perfect world the springs have equal tensions from the factory, the geometry of the frame posts WRT the frame center is spot on, the post/arm pivot friction is the same and the straddle cable is un kinks so that the two "sides" of it are the same lengths. That's a lot to be dead on in real life. After some use all these factors drift from their OEM state anyway and follow up service (like when replacing pads) generally requires some small tweaking of spring tensions among tohet adjustments. There's a reason why manufactures include these spring tension screws. Oh BTW Shimano only has a single side screw on their most popular cantis, what do you propose to do then? Andy