http://raceface.com/instructions/CRANKS ... _crank.pdf
"All RF cranks are designed to have a 48.5-49.5mm chainline when installed on a 113mm ISIS crank"
This will be the distance of the middle ring from the centre line of the bike.
Working backwards, you need to find the chainline of the rear sprocket.
By measuring between the axle faces (that butt up to the dropouts) find the midpoint of the hub.
Then measurehow far the sprocket teeth (centres) are from the centre line.
Adjust the length of the BB axle to suit. eg, if the rear chainline is 53mm, the front has to go out to 53 too, so the BB needs to be8mm longer: (53-49) X2 .
This will move the pedals out a bit but it's no big deal.
Give a man a gun, and he can rob a bank.
Give a man a bank, and he can rob everybody.