Some cheap single bolt posts slip and creak, some are all fine and dandy. I find the Langster post slips and on me after a few rides and creaks all the time. I have a cheapo Kalloy single bolt on another bike that's stayed put for years. I also have a single bolt post on my road bike that stays put. With all the single bolt posts I've had, I'd say half slipped and that the Langster's post is the worst. I think on the Langster a carbon post would be good because it'd smooth out the ride a little. I've been pretty anti-carbon on most parts of the bike, but after a few long rides I'm reconsidering one on my Langster.