Daft question for some but not me. I´m starting to build up a smallish lugged classic frame with planned measurements of mid btm brk to mid tt of 51 cm, top tube legnth m-m should be 53 cm. Now I´m not sure what lugs I should be using......74 deg, 73 deg, 60 deg. Can someone advise me please, as of yet never had to build a frame small than a 54 cm. Shoulda paid attention at school as all this maths is doing my can in. cheers.