So, in theory BB30 setups are able to have a lower Q-factor than GXP because the bearings sit inside the frame. Does anyone know if this is true in practice? Would it affect chainline then as well?

I.e., If I have BB30 SRAM Force cranks set up with a corresponding BB30 frame, will the Q-factor be lower than a GXP SRAM Force set up with a corresponding 68mm threaded frame?

For reference: https://en.wikipedia.org/wiki/Q_factor_(bicycles)



I've got a GXP SRAM Red crank now, and with a little bit of wheeling and dealing can end up with a BB30 Force crank for my BB30 frame. Will I just save 100 grams in making the switch, or will the Q-factor be reduced as well?

BB30 cranks do have a slightly narrower Q-factor. But it is not substantial, and it's pretty much not noticeable. VeloNews did a comparison a couple years ago. If you google it, you might find it.