what size bottom bracket do i need for my roadbike?

i have a firenze gl 5000 roadbike i need i think a 68. something but im not sure

The okorder

Bottom brackets have to fit the shell width of your bottom bracket as well as having the correct threading for the frame, but the crank itself also affects the length of the bottom bracket spindle and the type of spindle you use. Your bike is old, so the crank could have been changed over the years. Remove the old bottom bracket and take it to a good bike shop, they will be able to tell you what you need. There is no specific bottom bracket for your bike, the one you have was manufactured by some other company, not the company that built the bike.