Finally managed to swap fork and test the bike also with the 420mm one
I did 600km with the 395mm fork and around 250km with the 420mm
FM316 with 395mm fork-Ride feel is more similar to a road bike.
-Stable also downhill on gravel as you feel more "in" the bike rather than on top of it.
-Using the flip chip with 50mm rake steering feel was alright with cheaper aluminium wheels but using carbon Tagoola XPLR it's started to be a bit twitchy on uneven gravel, I'd probably switch to 45mm rake.
I'm using a negative 6 deg 80mm stem, which can give its contribution to the steering responsiveness.
-Main drawback of this configuration for me was ground clearance, no problem on flat gravel roads but on very easy trails with rocks and roots pedal strikes are quite frequent even if I ride carefully. I had to keep in mind ground clearance also pedaling in roundabouts on tarmac where I never had problems with the road bike.
170mm 2x grx cranks.
FM326 with 420mm fork- Front end of the bike is definitely higher, I completely slammed the stem and I'll change it to a -17deg to lower it even further.
- The steering feels much more solid and precise especially on fast but uneven gravel.
- Agility of the bike is not compromised though, the feeling of being "in" the bike vanished but the bike feels more playful overall; agility is now more a side-to-side freedom of movement rather than linked to steering responsiveness.
- I tried my idiotic roundabout test and the limit of pedal strike is definitely higher now, it makes little sense but it gives me peace of mind when pedaling mid-corner.
- Drawback of this combo is mainly related to my positioning on the bike, I really liked the 75deg seat tube angle and now I have to run my saddle all the way forward on the rail to try and replicate the same position.
All things considered I think I like the 420mm fork more because it's more versatile for the type of terrain around here and overall the bike feels more playful.
The FM316 stack and reach figures with a higher BB would be ideal.
