Pondering getting a custom made and I’m trying to work out what the measurements for what I want to carry over from my current bike and what I want to change. How do you measure head and seat angles?

Easiest way is with a digital angle gauge. There are iPhone apps which do it, and I’m sure other phones have similar apps too.
Otherwise it’s very difficult to do accurately.

There’s an I phone app. if your that way inclined 😉

If not you can get a Bevelbox, used for setting tool angles e.t.c works well. You just neeed a flat datum surface to take a reading off to set it and for the bike to stand on while being measured.

I use a photograph and powerpoint 🙂

An important question is do you measure them with suspension sagged or not…

Another thing to consider: if you are going to take seat/head angle measurements and give them to a framebuilder to replicate, he will also need to know the exact axle-to-crown measurement of the forks you had on when the measurement was taken. Without that the angles won’t mean much.

As long as you take all components that will have an affect on the geometry (fork axle crown,offset and rim tyre depth etc) into consideration, the design, once on the design programme can easily be adjusted to account for any component changes.

have you asked the frame builder. I’d have thought they can put a frame in their jig and take a reference.

The best thing possible would be a CMM, but doubt any frame builders will have one of these, if you anyone in Quality engineering they may have one.

Whats the Iphone app ?

I use a photograph and powerpoint

How do you do that then?

iphone app here

You could also use an inclinomter, as used by backcountry skiers/snowboarders to measure slope angles (in order to assess avalanche risk).

Basic ones are pretty much a protractor with a dangle needle, so aren’t expensive.

I use a photograph and powerpoint
How do you do that then?

stick photo into powerpoint and make sure wheels are level, and either rotate a line until it lines up with the tube and then in properties record it’s angle or use a free right angled triangle to do the same and use trig.

I dont have a £400 clinometer iphone 😉