Stack V Head Angle.

I am trying to suss this out in my head but….

If a bike has a 68degree headangle and you fit a 1 degree angleset you would need to fit a 2cm or 1cm linger for to maintain the same stack height.

I know the wheelbase will grow.

Thoughts?

The stack won’t change because your upper headset cup will most likely have to become external to accommodate the steerer offset. Reach will become shorter though.

Wtf is a linger?

If by “stack” you mean the height of the front end relative to the bottom bracket, then yes it will go down a bit, and also your bottom bracket will go down a bit.

Relative to the ground the front end will drop (ignoring a few teeny bits) by
[ac] x (degrees slackening) x Pi/180 x cosine(head angle)
where [ac] is the axle to crown of your fork.
Your BB will drop by a around half that, so your stack will drop by around half that.

Plugging some numbers in taken from a random bike on the internet (medium sized Trek Fuel) we have stack 58, reach 44, chainstay 44 (give or take a few mm) fork a-c 50 (in cm). We get around 3mm of drop in the front end. You would need to increase the a-c of your fork by a bit more than that to get the heights back to where they were.

So, back to what I said. A zs44 top cup becomes external when you fit an angleset. Actual stack won’t change.

Thank you very much for clearing that up for me.

Hyperthetically speaking if you wanted to keep everything else constant like seat post angle and BB drop you would need to increase the fork axle to crown measurement.

A 1cm increase would do this? I cannot change my fork in 5mm increments.

I wouldn’t bother, both of those changes are positive in my books.