Giro, can this guard be used in addtion to the regular outer chainring? I.e. with a triple crankset can it function as the fourth outermost ring? The spacers and the cutout suggests that this would be the case. Could there be a dependence on the crank in this?
There's one from Velo Orange that's a bit smaller (46 tooth max, I think?) that allows the use of two chainrings - just get taller bolts and stick it on
http://www.velo-orange.com/suchgu.html