Originally Posted by
cc700
those gxp s300's should have supplied spacer rings that go inbetween the cups and the bb shell. throw those on(or get some more) and it will move your chainline out but the millimeter or three of clearance you gain will be worth any slight(read: barely perceptible) chainline issue it causes.
same deal with my ftp. spacers work wonders, its IMO one of the best advantages of the external bb design.
Unless your BB shell is somehow narrower than 68mm, using the spacers will usually make it impossible to install the nds crank arm because it won't bottom out on the spindle as it should when properly torqued.
Those spacers are supplied with all GXP BBs - regardless of what crankset they come with - to be used in the event of pairing MTB cranksets (which typically have longer integrated spindles than road/track cranksets) with a frame having a 68mm shell. Adding two 2.5mm spacers instantly turns a 68mm shell into a 73mm shell, allowing you to use MTB cranks.
Trust me, I have spoken with SRAM about this.