This bike has a steeper head tube, reducing trail. But reducing rake (even if it goes negative), increases the trail again.
Stability is more complicated than just that, though... iirc bicycles have a bunch of nodes, including 1? 2? that are unstable but slow enough that riders don't notice they're compensating.
This claims stability is more determined by fork ~trail. http://avaghon.nl/download/Naloop_Bikestability-Forkrake.pdf
This bike has a steeper head tube, reducing trail. But reducing rake (even if it goes negative), increases the trail again.
Stability is more complicated than just that, though... iirc bicycles have a bunch of nodes, including 1? 2? that are unstable but slow enough that riders don't notice they're compensating.