Yes, and since Uncle Dave based his model off of listed effective seat tube angles, they mostly fail at communicating where your saddle actually ends up.
I can at least confirm that, even slammed all the way forward on the saddle rails of my XL Bronson, my seat doesn't end up anywhere close to a 75° STA. My hardtail has a true, straight-tubed 75° STA, and the horizontal setback from BB to the top of my seat post is 182mm. The 75.3° effective STA on the Bronson actually gives a riding position ~75mm further back over the rear hub at full ride height, due to the ultra slack actually sta. Accounting for suspension sag, those numbers diverge even further.
The only info needed to communicate this in a geo chart are: a) actual seat tube angle, and b) the horizontal distance that this line is offset from the BB.
May 28, 2019, 8:07 a.m. - Skyler
Yes, and since Uncle Dave based his model off of listed effective seat tube angles, they mostly fail at communicating where your saddle actually ends up. I can at least confirm that, even slammed all the way forward on the saddle rails of my XL Bronson, my seat doesn't end up anywhere close to a 75° STA. My hardtail has a true, straight-tubed 75° STA, and the horizontal setback from BB to the top of my seat post is 182mm. The 75.3° effective STA on the Bronson actually gives a riding position ~75mm further back over the rear hub at full ride height, due to the ultra slack actually sta. Accounting for suspension sag, those numbers diverge even further. The only info needed to communicate this in a geo chart are: a) actual seat tube angle, and b) the horizontal distance that this line is offset from the BB.