Uh oh, may have a problem with the Cannondale...

It came with a Shimano triple RSX groupset and now I want to install a DA 7400 112mm spindle bottom bracket. Is my double crankset going to have problems with the frame? I installed the non-drive side arm on the RSX bb and the very tip of the cranks were slapping the chainstays, can I safely assume that the bottom bracket for the RSX is shorter than 112 and therefore my cranks will work?