Originally Posted by
Kontact
You could use reach, STA, HTA, BB drop and front center to take a stab at rake. And you can derive front center if you have the rest of the numbers. If all the numbers were accurate your rake would be within 2mm.
In practice, some posted geometry is not accurate enough, but most modern bikes are designed on CAAD so they are more likely to be on. I tried figuring out some missing numbers on an old Cannondale and found that the published dimensions didn't work together.
But deriving trail without rake isn't going to work because all trail is is a "ratio" between rake and HTA.
Juggling variables, thanks Kontact. In a my little database of 15 or so bikes in the adventure/gravel/touring genres, about half publish rake/offset, and only a couple give trail numbers (Vivente Gibb, Soma Grand Randonneur). Perhaps this is because there seems to be very little variation in offset, most makers somewhere in the 45mm-55mm range. The Soma GR is an outlier, on purpose, making low trail (32mm) a marketing feature, and offset is predictably higher at 69mm.
Although my sampling of relaxed geometry bikes is tiny, it suggests that the "industry", generally speaking defaults to a medium rake/medium trail. And if that's the case, the front end handling of these bikes ought to be fairly similar among them, other variables being reasonably equivalent. Would you agree or disagree with this theory.
Another spotty metric among bike makers I've noticed is BB Height. Most firms report BB drop, but lot of them don't publish BB height, Salsa for example.
I'm drifting off-topic here, so I'll start a new thread in the Fit section.