80mm will be spot on.
Can I ask a couple of questions as I have another '96 Explosif I'm in the process of acquiring bits for? Does it have normal cable stops on the top tube? The one I have has some kind of weird hydraulic hose guides on the top tube, which just don't look right to me. Also, is the Columbus Max sticker in English or Italian? It might sound like an odd question but the one I've got has had some horrid rattle can paint job done at some point and the original decals are long gone.
