Reverse math it:

108" - 14" (widthx2) = 94"

94" - 52" (heightx2) = 42"

42" = maximum length

With the fork removed I'm sure a 64cm frame can fit in a 42 x 7 x 26 box. A neat tricjk is to measure the length and mark the tape then wrap the tape around girth of the box from that point, it's easy to save a few inches that way.