loose seatpost, even though its the correct size

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loose seatpost, even though its the correct size

21 posts & 13 voices | Started 6 months ago by greeble | Latest reply from GlitterGary

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greeble - Member

I find that my seatpost on my giant trance creeks from time to time. I've narrowed it down to the fact that the seatpost is quiet loose when inserted into the frame. When the seatclamp is undone I can move forwards/backwards, left/right about 1-2mm each way.
to get the creeking to stop I have to tighten the clamp up super tight.

The frame is 30.9 and the post is also 30.9 upon inspection inside seattube it has bare metal for the 1st 30mm then its ano'ed black like the rest of the frame. This isn't right is it? Does anyone else have a trance they could confirm?

Posted 6 months ago #
wwaswas - Member

does sound like a slightly oversized seattube.

I'd take it to a giant dealer to get it inspected - only 30mm of frame holding the seatpost is asking for frame failure

Posted 6 months ago #
alfabus - Member

can't comment on the seat tube internal finish, but have you tried shimming it with a coke can to make it a bit tighter?

Dave

Posted 6 months ago #
wwaswas - Member

but it sounds like the seat tube is not the same diameter all the way down (ie post only touches first 30mm) and this allows post to 'rock' a bit in the tube - so shimming wouldn't work as it woudl only affect the first 30mm?

Posted 6 months ago #
Tim - Member

Is it the original post?

If not, what make is it?

Have you checked its actually the size it should be?

Is the seatpost excessively worn?

Posted 6 months ago #
nmdbase - Member

Buy a decent seatpost as they are more accurately sized, my Haven one is snug whereas my Nukeproof one wasn't.

Posted 6 months ago #
Sam - Member

does sound like a slightly oversized seattube

Or undersized seatpost - which is more common than you might think. I'd take it back to where you bought it, assuming it's the stock post which came with the frame.

Posted 6 months ago #
nsaints - Member

I had the same on a Niner frame - different posts all slipped despite trying various internet based advice

I eventually got around it by fitting a 31.6 > 27.2 seatpost reducer
the new 27.2 seatpost has not slipped or creaked at all since

Posted 6 months ago #
alfabus - Member

but it sounds like the seat tube is not the same diameter all the way down (ie post only touches first 30mm) and this allows post to 'rock' a bit in the tube - so shimming wouldn't work as it woudl only affect the first 30mm?

I'm a bit confused by the OP... he describes being able to waggle it 1-2mm in all directions with seat clamp undone... taht would imply to me that the top of the tube is loose too. I'm not sure of the relavance of the anodizing in the tube - wouldn't the seat tube bore be narrower where there is anodizing?

Dave

Posted 6 months ago #
wwaswas - Member

maybe it's just where it's been clamped the seat tube is a little tighter on the post so this has caused the wear at the top.

I'm tendign to think tryign an alternative post as a starting point might be better...

Posted 6 months ago #
greeble - Member

the seatpost is an sdg i beam jobbie. The post is brand new. I think it may have been reamed for the 1st 30mm and its slighty too wide. I'll take some digital calipers to it when I get the chance

Posted 6 months ago #
alfabus - Member

If it is wider for the first 30mm, and then the correct diameter further in, I'll stand by my original suggestion of a coke can shim. Obviously in that case, you'll only need the shim to be 30mm deep.

Dave

Posted 6 months ago #
alfabus - Member

could it be that someone with fist of ham has tried to force a larger post in? effectively 'reaming' the top 30mm before they gave up, but the damage was done.

Did you buy the frame new / recently?

Dave

Posted 6 months ago #
greeble - Member

I bought the frame second hand but in excellent over all condition. and the seatpost is new. I'll have a look with other seatposts and digital calipers

Posted 6 months ago #
flow - Member

Different post actually come up different sizes (even though they are supposed to be the same) My brother has a Nukeproof post and its mega loose in the frame, whereas the previous post was fine.

Posted 6 months ago #
nsaints - Member

My frame was 2nd hand - I concluded that it was a worn frame after trying everything else I went down the seatpost shim route

Posted 6 months ago #
goldenwonder - Member

Most Giant frames are bare metal indside the seat tube, the two trances I've had were anyway, as well as my Reign, XTC etc etc.
Sounds a bit like the top may have been splayed open for some reason, or run with the clamp loose, streching the top.
I'd take it to a Giant dealer to have a look at (which I happen to work at)
Whereabouts are you?

Posted 6 months ago #
MrK mkII - Member

i bought a control tech 27.2mm post for my inbred and that was as baggy as a giant's stocking on a baby's foot. the thompson that replaced it was as snug as a snug thing... so i guess i'd recommend trying other posts to see if the problem persists...

Posted 6 months ago #
emac65 - Member

I've had this with a 27.2 post(can't remember what brand it was) in my Kona frame,swopped to a Thompson one & it was a perfect fit

Posted 6 months ago #
Garry_Lager - Member

Ale can shim for sure worth trying but it might be too thick lower down the seat tube - sounds like we're talking about an arse hair too big or too small. Different post might solve the problem.

Posted 6 months ago #
GlitterGary - Member

+1 for an ale can shim.

I find that Badger Tangle foot is a good can to use. Or Newcastle Brown Ale, if you're feeling a bit mad.

Posted 6 months ago #

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