For the 1-1/4" tube a 4" or a 4.5" die is fine. The larger one is nicer because most of the bends are on the outer side of the cage and there's really no reason for them to be overly sharp.
For the 1" tube I used a 3" radius die. The only place you use this is on the lower front arms and the outboard bend near the spindle is a smaller is better type thing. 8 bends for a ~$200 die set.....
