Should the open side of a seat clamp be on the same side as the seat tube opening or the opposite side or does it matter. I've slippy seat post issues 😆

Open side same as slot.

Ditto

Opposite side

ditto

The instructions with a carbon post I got says turn the clamp so the open side is opposite the slot in the frame.

3-2 to the opposites, any more ideas here?

Open side (where the bolt is) should be the same side as the open side of the seat tube. Else it ca't tighten as well and the seatpost slips

Slippy Carbon seatpost could be due to the seatpost not gripping. get some grease for the seatpost with that polymer stuff on that helped my slippy seatpost.
🙂

You should have the slot in the tube aligned with the slot in the seat clamp (open section). If you don't then you are make it much harder to tighten the clamp.

Not sure why people would think its best to align it on teh opposite side it does make any since.

If the slot in the tube is facing the rear wheel just cover said slot with a bit of thini tape and this prvents dirt etc getting in.

The instructions with a Specialized carbon post I got says turn the clamp so the open side is opposite the slot in the frame.

Mind you, they're only one of the largest bike manufacturers in the world, so I guess they know nothing compared with the collective wisdom of STW.

Oh – and instructions for the new Thomson seat clamp also say to fit it opposite if using it on a carbon frame.