Printable View
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.
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.
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...