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Old February 24th 19, 05:14 AM posted to rec.bicycles.misc
John B. Slocomb
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Posts: 805
Default help unseizing seatpost!

On Sat, 23 Feb 2019 14:31:28 -0800 (PST), vinokourovswaterbottle
wrote:

looking for your help on this one...

So I have this road bike with carbon fibre frame bought second hand and the seatpost is stubbornly seized inside it.

I have tried spraying generous amounts of normal lubricating oil and penetrating oil from both sides (top and bottom of where the seatpost meets the frame, reached the bottom by removing some screws to gain access to the inside of the frame), this was done several times over the space of a day and even leaving it sink-in overnight...

I have also tried heating the frame pouring hot water as I've seen in some online videos, on top of that, I have also tried heating the frame with a heatgun at a relatively safe temperature (the heatgun has a digital dial to control it).

I have also tried melting silicone on the nose of pliers and grabbing the seatpost with them, there was some grip but not enough to unseize it, the force being applied was so strong that the pliers eventually went through the dried silicone leaving some cosmetic marks on the seat post, so I had to stop to prevent more damage.

Additionally, when I try grabbing and turning the saddle to unseize the seatpost, the saddle railings on the seat rail clamp come off, making it impossible to continue turning unless I put the railings back on the clamps and tighten them; needless to say, no matter how much force I apply, it's always the saddle railings coming off but the seatpost doesn't move a millimetre...

None of it has worked so far, but I don't wanna give up.

I've been reading some literature regarding this matter online and tried to work out the logic of way number 14 on this website (https://www.sheldonbrown.com/stuck-seatposts.html) but I don't quite understand how to do it. It might be the way!

I'm attaching some pictures of the frame and the seatpost with as much detail as I can.

https://imgur.com/a/7sOfFje

Look forward to your suggestions and help.

ps. cutting off the seatpost is not quite an option at this stage.



It seems that you are being careful when you heat the carbon fiber
frame and I would emphasize that. It might also be noted that as a
general statement carbon fiber has an "extremely low coefficient of
thermal expansion (CTE)" see:
http://www.performancecomposites.com...bon-fiber.html
I would also be extremely careful prying or twisting on a carbon
frame. Carbon fiber while quite string in some directions can be
rather weak in others.

You might look at:
https://www.youtube.com/watch?v=BieV2J-DUKg
See also:
https://www.bikeradar.com/forums/vie...php?t=12996386

I have used a lye (caustic soda)-water mixture to remove aluminum seat
posts from steel frames but have no idea whether lye effects carbon
fiber. If it doesn't then that is a relatively easy method although
the lye mixture is very caustic and you need to be careful when using
it not to get it on yourself or your clothes.

See
https://www.youtube.com/watch?v=7Juqbl4wiXA
https://www.youtube.com/watch?v=mQDHSVpvqzA


--
Cheers,
John B.


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