Thanks Blackstridaaustria, Bill and ttakata73 for all the infos. It seems in the photos that the B67 and the strida leather saddle are perfectly horizontal. If so probably any of the solutions are good and maybe the strida saddle offer more confort because is wider. Today I was seat in a conventional bike with a B67 and it seams to me that the springs are too strong (for my weight - 70 kgs). Maybe the springs of strida seat are weaker?