my first road blike build

sram have a 24mm ID bearing on both sides and use a reducer on the nds to take the ID down to 22mm. they either have it pressed in the bearing or they use a removable shim as this one:

http://forums.mtbr.com/airborne/goblin-bottom-bracket-928096.html#post11412894

you could try removing the reducer and end up with a regular 24mm bb, but you might then need a custom dustcap.. might be worth asking someone that knows more, eg. @mdcc_tester