Great read Mike! As a lover of (relatively) slack seat tube angles there's a lot here I agree with. A couple quick thoughts.
When discussing slack seat tubes it's worth considering bar height. A lot of the early STA developments you mention would have came from road racing with very aggressive positions. People didn't necessarily ride trail back then so this road fit is what was translated over to the first MTB's. And there were narrower Q-factors then to!
I find when you lower the hands (and torso) it's easy to feel the hips wanting to push back. As I've aged and raised my handlebars to be able to sit with a straighter back for more comfort I can feel my hips wanting to pull forward. Kinda like standing up out of a chair. So I've now come to appreciate slightly steeper STA's and would say around 75 degrees at 25% sag is optimal for me on a hardtail. At the fork travel I run that's still a 73-74 degree static STA so very slack by current trends.
I feel like one way to be able to better compare fit is to convince everyone selling hardtails to list sagged geo. This would correct both stack heights and STA/HTA's. As reviewers of bikes I feel like that's something you could push for. I know Cotic do a great job of this listing their bikes at 25% sag. They also sell some really well designed all-around trail bikes, like the BFE Max with a 140 fork and 74.5 STA (sagged!).
Oct. 8, 2022, 2:44 p.m. - bushtrucker
Great read Mike! As a lover of (relatively) slack seat tube angles there's a lot here I agree with. A couple quick thoughts. When discussing slack seat tubes it's worth considering bar height. A lot of the early STA developments you mention would have came from road racing with very aggressive positions. People didn't necessarily ride trail back then so this road fit is what was translated over to the first MTB's. And there were narrower Q-factors then to! I find when you lower the hands (and torso) it's easy to feel the hips wanting to push back. As I've aged and raised my handlebars to be able to sit with a straighter back for more comfort I can feel my hips wanting to pull forward. Kinda like standing up out of a chair. So I've now come to appreciate slightly steeper STA's and would say around 75 degrees at 25% sag is optimal for me on a hardtail. At the fork travel I run that's still a 73-74 degree static STA so very slack by current trends. I feel like one way to be able to better compare fit is to convince everyone selling hardtails to list sagged geo. This would correct both stack heights and STA/HTA's. As reviewers of bikes I feel like that's something you could push for. I know Cotic do a great job of this listing their bikes at 25% sag. They also sell some really well designed all-around trail bikes, like the BFE Max with a 140 fork and 74.5 STA (sagged!).