Moving seat post

cant say i have had this issue, perhaps could be the bolt, or the clamp..have u tightedned it too much that u have caused the seat post to become indented and now slipping down.

I have tightened the avanti alloy seat clamp pretty tight. But theres no indentations or damage as yet. It will slip down mm by mm over a 1hr ride. Just doesnt seem right.

I know this may sound like a silly question but is the seatpost the correct size/diameter? Also, do you have a seat clamp which goes around the seat tube or is the bolt integrated into the seatpost. Either way, have you check to make sure the bolt is not stripped.

assuming it's the right size and the bolt and thread are ok........

test it by whacking the nose of the seat kinda hard. It shouldn't twist.

You've gotta check all the bits, like, make sure the clamp ends aren't touching in the middle, or the frame gap isn't coming together, and that nothing is stopping the screw being tightened way up

seat post is right 27.2 and clamp seems ok going to give it the wack test and see what happens

Some quick release type seatpost clamps just won't tighten enough to hold a smooth seatpost.
If this is the case you can look at a different clamp or a less smooth post or both.

cruisin said:

Some quick release type seatpost clamps just won't tighten enough to hold a smooth seatpost.
If this is the case you can look at a different clamp or a less smooth post or both.

Good call. If it is a smooth seatpost maybe give it a light rub with sandpaper/emery cloth to rough it up a little. Obviously not the whole stem but only the portion which won't be seen. It might help.

If the bolt in the clamp is this type, with the 2 bits, sometimes the 'nut' end, and/or the bolt has to be cut. If the bolt goes through right through to the unthread bit, it obviously won't tighten properly, even if it feels as though it is. It's often hard to see if the the bolt is 'stopping' on any parts of the nut end

[img]bonthronebikes.co.uk473219.jpgOpen ↗[/img]

531Aussie said:

If the bolt in the clamp is this type, with the 2 bits, sometimes the 'nut' end, and/or the bolt has to be cut. If the bolt goes through right through to the unthread bit, it obviously won't tighten properly, even if it feels as though it is. It's often hard to see if the the bolt is 'stopping' on any parts of the nut end

[img]bonthronebikes.co.uk473219.jpgOpen ↗[/img]

Aye. I've had to shorten the nut end on a seat clamp bolt before.