Thanks for that.
Originally Posted by Sheldon Brown
There is a sligth variation in tension resulting from the varying angle between the two straight runs of chain as the axis of the chainring rotates, but this has not generally been of a sufficient magnitude to cause any problem in practice for me.
I have vertical dropouts, so I am planning on getting a tensioner of some sort. Wonder if a spring/flexy-type tensioner would be a better choice for me, as opposed to one of the rigid ones? I guess, on the other hand if he's riding 'em fixed it must not be that much of an issue.