Adjusting the chainline on a FG or singlespeed bike - and you don't have the right BB width. Now, of course, you can play around with the dishing of the rear wheel (remember that you have also to move around the spacers on the rear wheel's axle, or else you didn't really "get it" how redishing the rear wheel is supposed to change the chainline), but there's a better way, if your chainline is off by only a few mm: spacers on the chainring bolts.

And not only that: if you have a road crank, you don't necessarily have to put your chainring in the outer position - remember, there's the inner position, too. So you can put the chainring there thus moving the chainline closer to the bike's central symmetry plane.


A straight chainline is critical. Just one mm away from the perfect straight parallel can mean a falling chain, and I don't have to tell you how annoying and even dangerous that can be.