Originally Posted by
Iride01
Then I think where we differ is that I don't assume that people transferring their position from one bike to the other do anything more than measure saddle position from some point on their bars. And most that measure saddle setback will just measure that from the seat tube and not the vertical off the BB. But that's just an assumption I've come to based loosely on things I've read here and seen done in real life.
Maybe I'm wrong to think that way. I just don't assume from the get-go that everyone always does something correctly. But I also don't assume they are doing it wrong if they don't add something that indicates they are doing it wrong. So sometimes like in my first reply to the OP in this thread post was just a bit of info to get the OP thinking about that. They didn't ask any questions about it so I assume they either understood the implications or it wasn't of consequence to them at the moment.
I am certain that you are right: People do all sorts of dumb things. I just don't get discussing those things as if they are a valid alternative.
Especially when people seem aware of changing stem length and the fact that bikes have different TT lengths. But if you are measuring from the stem, the stem stops being a variable and becomes the reference. Which is not a terrible thing with a tri bike, but crazytown when it comes to a bike that you don't want to lean on your arms.
Anyway, even if you decide to measure from the stem, that still isn't going to reference the seattube angle.