@Serge, regarding tire clearance. 40mm between the stays might be 32mm width as measured max, as ISO4210 for road bikes (confusingly racing bikes) is 4mm. I would check the drawings before assuming that there is more or less clearance vs. your 268 because that 4mm min clearance spec might be driven by FD cable placement, ST or fork crown clearance. With the 266SL, it does look like FD cable would be the main clearance issue, but since I am actually planning on a 1x build, it wont matter to me. Not sure what the case is with the 126.