Yestreday, I did check the clearances of the tyre and the chainrings on the rear triangle. I also checked the chain with the tubes which can be a problem with really small rear triangles. Everything is like on my drawing, we can carry on.
Dégagement des plateaux
Dégagement avec un pneu Knobby Nic 2.25
Clearance with a Knobby Nic 2.25 tyre