Help need with what lugs I need

[savine]

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.

[EricKeller]

download rattlecad or find an online version of bikecad. I have no problem with math, but the idea do doing this by hand when I don't have to gives me the shakes. The problem with small bikes is toe overlap, this will give you a bias towards slacker head angles, and 74 is too steep for most bikes anyway.

Most lugs will work fairly easily at 1 degree off. Brute force can get more slack than that.

[suhacycles]

No full scale drawing? I'm guessing your head angle is gonna be around 72, the seat angle about 74 and the down-head tube angle around 59 but your drawing will tell ya...