I just found out the 31.6 post has an added reinforcement inside. Not sure if alloy or carbon though, for sure it adds grams could be better.
I wanted a no setback seatpost for a better fit on the bike than the one it came with. Seems good. Original post was also carbon fiber. Didn't notice a big difference in regards to flex versus the original.
It helps dampens the road buzz along with the right tire pressure.
