Rail Type Seat Posts, How well do they hold?

I just went through my second rail type seatpost in less than a month. It’s on my coker. I was doing fine before I got my T7 handle with the normal 4 bolt seatpost. But whenever I hit a big bump or pull the handle back really far the seat and handle just goes. There is ablosutly no strenght in it. It rotates amazingly easily.
I tighten it as much as I can but it still goes out. When I’m just doing smooth riding it’s fine, but as soon as I hit a bump it moves on me. :angry:
I hear about everyone saying that they lean on there T7 and rest their “jewels” But I fear doing that because I know it will just get pushed down in.
I ordered a new seatpost and will be installing it this weekend. But I need to know. Has anyone else had a problem like this?
After the problems I have had I have no idea how people do muni with them.

Is it the seatpost guts that are rotating?

The seatposts that use a single bolt to tighten the guts to the rails are more problematic than those that use two bolts. With the single bolt designs the single bolt is responsible for both clamping force on the rails and holding the seat angle. The two bolt designs like the KH and Thomson hold the seat angle much better and will not slip unless one of the bolts breaks.

But even some of the two bolt designs, like used on the Primo Rod BMX style seatpost can have seat angle slippage problems. The only thing holding the angle is friction. The bolts only tighten the friction. Friction alone is not really good enough.

So get something similar to the KH rail seatpost or the Thomson.

Which seatpost are you using? There are some like the Thomson or KH that have 2 bolts, one front and one back that wont allow that to happen.

Okay, thanks for your help. I’m pretty sure I ordered a Thompson. My dad has it now and he will bring it out this weekend.
It is the guts that were slipping. So hopefully this new one will work better. I’m just really annoyed by this.

Yea I’m using the KH. It never slips out of place.