I've used a suspension seatpost on a commuter bike, never used it off-road though. It added a nice bit of cushion for the small bumps and cracks you encounter on uneven and poor road surfaces, but I could see them being easily overwhelmed in typical off-road use.. they don't compare to a proper short-travel dual suspension frame.
With the commuter I ultimately moved back to a rigid post: not because of the varying BB/saddle distance -- which I didn't really notice much -- but beacuse of the sideways (yaw) and angular play it introduced in the saddle.
If comfort tends to take precedence over raw efficiency, then they're worth some consideration. It also depends on the kind of terrain you like riding on as well.
John90210 said:
Are they much heavier than alu. and carbon fibre seatposts?
Yes, they tend to be (at least) a couple of hundred grams heavier.
So what is the best thing to buy, suspension or rigid seatposts? And can anybody recommend any of either type?
I'll be annoying and suggest something out of left-field that only indirectly answers your question: keep your rigid seatpost, and start getting used to searching for the "hardtail line" through your off-road tracks: the line that gets you through while avoiding the bumps and nasty stuff. (When you can't avoid it, then rise out of the saddle a bit and relax your elbows a bit, so your body doesn't have to take the abuse)
These kinds of things are some of the reasons why people say learning to ride XC on a hardtail builds your skills a lot quicker/better than riding a dually from day one. Like those crazy Japanese TV game shows, a hardtail punishes you for your mistakes, forcing you to learn technique... whereas a dually will let you be lazy and roll straight over anything
