You are completely right with ~40mm...
I used the drawing and forgot to use my own scaling in the final approximation. So my approach should have yielded 47.5mm

Quote from: JensenMacD on November 06, 2026, 07:29:59 AMMy thought based on the information is the following. Virtual STA of 74.5* and Actual STA of 79.5. But as you point out, the actual STA does not cross through the bottom of the BB but offset behind.

My thought is taking the distance of the offset and you would have to subtract that from what the actual STA pushes you forward. IF 79.5* moves the saddle 60mm forward and the offset is 40mm, then the saddle actually only moves 20mm forward.

Note I do not know if that offset is 40mm, I picked a number for my example.

The offset for your size looks to be around 95mm (horizontal distance between 79,5° line and BB)

Any info regarding the tire clearance?

Tideacebike