These are both excellent resources, thanks @jarsson and @zo541 for posting. A couple things that stand out to me after reading:
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Both trail and BB drop influence stability, but trail also affects steering.
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Jordan (first link above) and Tom (second link) disagree on BB drop. Jordan thinks gravel bikes should have a low BB for stability and Tom thinks they should have a high BB for “better balancing”. This tells me there is no ‘right’ answer here.
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Tom’s belief that ‘slow’ bikes have a higher BB and ‘fast’ bikes go lower is interesting. Neither Specialized (Shiv vs Diverge) nor Cervelo (P5 vs Aspero) follow that, but Trek (Speed Concept vs Checkpoint) does.
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Both agree that a few mm either way can make a big difference, both in terms of trail and BB drop.
Now for my next question: If the extra stability from a lower BB (more BB drop) comes from lowering the center of mass of the entire system, would putting a dropper post on basically negate any worries about BB drop? I mean, the differences in BB drop on these bikes is ~10mm. That pales in comparison to even a small 100mm dropper. Using a 100mm post probably doesn’t mean you’re going to drop your center of mass by the full amount, but even if you only lowered yourself 50mm, would that basically erase any differences in BB drop?