Seat...Stay Damnit!

C

Cúl-Báire

Likes Bikes and Dirt
My Damn seat post keeps sliding down as I am riding, it's annoying asthose spoilt little brats you see in shopping centers with there Mummys'...

I was wonding if anyone has any ideas how to stop it form sliding down the seat tube?.. The QR/Clamp is tight, very, you almost cant do it up...But still the post slides down whilst riding...Any ideas?

Also, Maybe Grip or someone can confirm a rider's tale for me: If you overtighten the QR/Clamp on the seat tube, will/can it crack the welds on the seat stays? I remember hearing this somewhere before!

Hope someone can help
-Cul
 
J

juzza

Likes Dirt
You proberbly have the wrong size seat post.( Does it fit snugly in the seat tube? is their play?) Do not overtighten what ever you do. Check you have the right seatpost first, if so clean it really well(metho) then check your clamp. Borrow a mates clamp for a bit and see if that helps.
 
K

kalem

Likes Bikes and Dirt
juzza said:
You proberbly have the wrong size seat post.( Does it fit snugly in the seat tube? is their play?) Do not overtighten what ever you do. Check you have the right seatpost first, if so clean it really well(metho) then check your clamp. Borrow a mates clamp for a bit and see if that helps.
Click to expand...
well you don't wanna clean it too good, it may sieze up and get stuck! i have a little grease on my post so it doesn't become permanent...
 
LordNikon

LordNikon

Uber Geek
What kind of post is it?

Carbon or metal?

My carbon one was sliding heaps until I cleaned all the grease out of the tube and off the post.

If it's a metal one then try putting a bit of dirt, sand is better, on the post and that should stop it.
 
L

lupine128

Likes Bikes and Dirt
for carbon, try a little talc (just a very small amount)
for metal, you want to have a small amount of grease as has been said.
sounds as if you are using the wrong post size for the seat tube. duck into your LBS and ask them to check the size of the seat tube for you, then stick a post of the right size in for a few minutes and see if that fixes it.
try and avoid sticking anything like dust or dirt in there, as it will eventualy contribute to making a nasty mess and fucking everything up. you end up with that really interesting greasy mud that makes it really hard to clean the damn thing properly.
 
C

Cúl-Báire

Likes Bikes and Dirt
It's the bikes original post, from the manufacturer (Avanti in this case)... It's an Aluminium post, I was wondering if maybe scratching the post might help a but, no big gouges or anything...

Interseting note, the post only slides down so far; about 3/4" from where I normally have it, after that it doesnt slide anymore :lol:

CulBaire wrote:
it's annoying asthose spoilt little brats you see in shopping centers with there Mummys'...
Chewy wrote:
just cause u live in corio...
Click to expand...
Your one of them spoilt brats aye Chewy :p
 
L

lupine128

Likes Bikes and Dirt
ummm, you haven't axed in really badly recently have you?
if the seatpost has taken a really hard knock it might have ovalised the tube slightly.
if all else fails, buy a longer post and push it down past where you usualy do, and it should stay if it only drops 3/4 inch anyway :)
 
LordNikon

LordNikon

Uber Geek
I'll have to try that talc trick myself Lupine...

My carbon post just wont stick... still!!!

Although turning the clamp around so that the closure is where the split in the frame is helped heaps.
 
C

Commander Dilsnikk

Likes Dirt
i had the same problem with a stock post on an 02 specialized p.3

i took it in and the shop gave me an allen key bolted collar instead of the qr one and it's fine now
pity i can't change the height so quickly though....i think the problem may also have been overgreasing of the tube by the guys at the shop but it's ok (if not perfect re: ease of height change) so i'm not complaining.......the fewer things on my bike that i have to worry about the better!!!! (and the lits is usually pretty damn long!!!! roll on internal drivetrains i say!!
 
LordNikon

LordNikon

Uber Geek
Remind me to beat the guy that sold me my carbon post severely about the head...

told me to use grease on it.

I didn't though... the only grease on it was from the previous post. It's all cleaned out now though.
 
L

lupine128

Likes Bikes and Dirt
apparantly it's as much because some grease can do nasty stuff to carbon as it is the fact that you shouldn't tighten carbon anything up as tight as steel/alloy.
basicly if it is dry you will get the same grip with less pressure, and avoid doint horrible things to the carbon part.
 
LordNikon

LordNikon

Uber Geek
The "no grease" thing is because some petroleum based solvents will dissolve the resin used to make a carbon post.

It depends on the type though:
Basically there are 3 types -
(stand by for Basic FRP one on one)
Polyester -
Bottom of the pile, used for basic fibreglass. Has little chemical resistance and poor bonding to hard, impermeable surfaces.
Vinylester -
Used for chemical resistance applications. Has much better bonding and tends to be more flexible than Polyester.
Epoxy -
Good bonding and superior strength. This is what should be used for all carbon fibre applications. It is more expensive though and therefore is often not used when it should be.

The reasoning for not tightening carbon posts too much is purely because a carbon/epoxy post will not be flexible enough to withstand being crushed. It will crack and therefore lose most of it's strength.


LN
*used to work for a F/G importer*
 
S

simooooona

Likes Bikes
dont do it up too tight or you can like warp the seat post... unless its hell strong... my mate did that... shitty seatpost but
 
Grip

Grip

Yeah, yeah... blah, blah.
Thanks to all of you for heaps of info on seat posts and carbon. Only leaves me one thing to say to Culbaire... yes you can damage your frame by overtightening the seatpost clamp.
 
C

Cúl-Báire

Likes Bikes and Dirt
Thanx Grip, I though I heard that somewhere, probably down at Marshalls (my LBS)...I seem to have fixed the problem by turning the qr/clamp around...Did 40km yesterday and it didnt budge any, and boy can you feel it on your ass now :oops:
 
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