Mountain Biking - seatpost keeps slipping

i have an adaptor to make my 27.2 seatpost fit the 30mm hole on my bike.i got the adaptor and installed it last oct.it started making a horrible sound and i took the quick release loose anough to raise and lower a little to see if it was dirt or a problem of lager importance but now it keeps slipping down i have to raise it about every 3 miles or so.all i did was loosen and retighten it didnt even take it apart.any suggestions on getting it to stay or a decent 400 mm long,30mm dia. seatpost.i really like the bontrager that is on there that is why i got the adaptor to switch from my old frame to this one.would getting rid of quick release and going regular help.this one really sucks.you got to set it just right or it wont work right.thanks for the help

Rough up the contact surfaces of everything concerned, post and the inside of the shim, with some sandpaper or file. A new, correct fitting seatpost is the best solution. Also, get a new keyboard with a working "shift" key.

i have an adaptor to make my 27.2 seatpost fit the 30mm hole on my bike.i got the adaptor and installed it last oct.it started making a horrible sound and i took the quick release loose anough to raise and lower a little to see if it was dirt or a problem of lager importance but now it keeps slipping down i have to raise it about every 3 miles or so.all i did was loosen and retighten it didnt even take it apart.any suggestions on getting it to stay or a decent 400 mm long,30mm dia. seatpost.i really like the bontrager that is on there that is why i got the adaptor to switch from my old frame to this one.would getting rid of quick release and going regular help.this one really sucks.you got to set it just right or it wont work right.thanks for the help


The quick releases are notorious for that. Try getting a bolt type collar. My friend has the QR type and he has to adjust his constantly. I have both and have never had any trouble with either, and I am a tubby 195 lb'er, so maybe it's the brand, I don't know. Regardless of how you solve it be sure to grease the seat tube or it will freeze up in there over time...

I was riding yesterday and it kept slipping.I got miffed and got a sharp rock,took it apart and scratched the heck out of everything(I had not read reply yet)and it did not do bad but it still slid a little.when done I went to an auto parts store and got a radiator clamp and put that around post until new 30mm arrives-I get to lbs and purchase,not sure which it will be yet since lbs may not have the size i need and i am going to eliminate quick release at the same time.I dont use it and never have had a real need for it since i do not do serious downhill or the like.I am a little over 200lb and i do not know what brand it is but it is gone soon.thanks for all the help(oh yeah shoving pine tags in the side did not work either)

My quick release on the MTB did that for a while too. My LBS suggested that I put a bit of grease on the pivot point of the quick release so that I could clamp it tighter. I did this and it solved the problem.

I just changed my seat post to a nut and a bolt (the fastener that came with it broke off) just plain old hardware store stuff. My seat has not slipped once since doing it.

thanks ngate the release is fine its the adaptor that is allowing the movement.the clamp is doing ok and i am having a hard time finding a 300mm at 390mm+ length in stock(bummer) but its stiil getting me where i need to go