Hi!

Just wonder if there is an accurate way of measuring Seat-Tube and Head-Tube angles on a built up bike?

I'm not an engineer and don't even have a plastic school protractor, but can always buy one. I do understood basic geometry, Pi, Pythagora's formula and so forth. A plumbline can easily be made... but I'm not sure if I'm thinking in the right direction or if there's a simpler method?

It's an old bike and I've searched in vain for it's geometry.

One thought I had was to draw lines on a photo in Illustrator and take measurements from that, but am uncertain as to how accurate that would be.

Thanks!