You start with 150 grit paper to remove all the deeper nicks and scratches, and the anodising, then go to 320 grit in soapy water..... but be sure to sand in a paralel stroke !!!
That should take 2hrs per arm.
Once you have an even grain appearing on the arms, sand them for about 40 mins each with 1200 grit in soapy water. Keep an eye on the finish, you don't want to polish them !!!!! Good luck!
Trust me I've seen it in the flesh and it rocks. The whole bike is like new.
