Topic Title

Quick question - anyone have any tips for removing a stuck seatpin (aluminium alloy) from a carbon frame (Look-type with aluminium lugs) without damage to the latter?

Dave B

The old trick with stuck seatposts was to turn the bike upside down and pour coke in from the BB and soak overnight.

While this worked for metal, I'd hate to think what it might do to the resin in a carbon frame.

They do say that if you don't use carbon 'friendly' grease on your seatpost, the carbon actually soaks up the grease and swells jamming the post in.

Paul,

The stuff in cola that does the business in such situations is phosphoric acid (albeit weak) & has little if any effect on carbon fibre itself, but is bad news for metal bits, so whilst it's OK for the frame tubes, not sure how the alloy seat lug & BB shell would fare.

Dave B

Seizure, techniques I’ve used in the past a penetrating oil (WD40) block any holes in seat post with a rag frame upside down, pour in oil and leave to soak in as long as possible. You can buy WD40 in 5 litre bottles from wholesalers.

http://www.toolsandscrews.co.uk/mm5/mer ... o-mess-pen

Leverage – clamp something in seat post (no too long) a twist.

Heat – not sure how this would work with carbon, pour hot water over the aluminium lug/frame and use a bit of leverage backwards and forwards once you get side to side movement you ve cracked it.

You are not the only one

http://forum.ctc.org.uk/viewtopic.php?t=6225

Re: grease stuff above. Don't grease a post in a carbon frame. As mentioned, you can get special carbon friendly grease, but I don't see the need.

To get it out, Sheldon Brown has the full list

http://www.sheldonbrown.com/stuck-seatposts.html

I've hacksawed a seatpost out before. It takes a very long time but will always work. Great care is needed not to cut into the frame, which is why it's so slow.

As mentioned, you can get special carbon friendly grease, but I don't see the need.

'cos if you don't your seatpost gets stuck

Thanks to all for suggestions; would probably favour the Coke option over WD40 - the latter has a tendency to get soaked into unlacquered carbon and make it swell up (much like the morning Weetabix if left in the milk too long!) which could exacerbate the trouble.
Should point out that this thread is all to do with a Look KG231 that I've been offered at a silly price of £75 as it was just gathering dust in someone's garage - are the weight and/or handling benefits over my existing steel race frame (Columbus SLX New) enough to make it worth parting with the dough in the first place?

Dave B

I've never known coke make any difference at all to a seatpost apart from making the seatpost very sticky.....

Hmm....maybe careful application of a hacksaw blade is the best option after all. A while ago (on a different frame) I did try the trick of using ammonia (and the concentrated "880" stuff at that!) for a stuck alloy post in a steel frame - this is supposed to be quite effective, though I had no joy at all. Of course, there is always a *very* slim chance that the post is in a position such that the overall saddle top-pedal axle measurement apes the current set-up I have, making the matter much less urgent until such time as (a) the frame badly needs a repaint or (b) the seatpost breaks....

Dave B

coke is the way i get steel diesel injectors out of aluminium heads on engines at work, eats away the carbon, different kind of carbon but probably the best way?

Surely eating away at the carbon is exactly not what is wanted here?

its not carbon fibre that egines produce! coke will eat away the corrosion from the alloy.

Just to update - have tried the penetrating oil & fizzy cola methods so far to no avail, so the suggestion of sawing it out looks favourite; with a little care and patience the frame should survive the ordeal. Any particular types of saw & saw blade to use, or will an ordinary Eclipse hacksaw or similar do the trick?

Dave B

You need two hacksaws. A normal one to cut the top off, about 2-3cm above the top of the frame, then a long thin one to go down inside the seatpost. I had to borrow one of these.

After cutting the top off, cut two parallel lines down the tube, about 1cm apart. They don't need to go completely through the tube after the top part - within 1mm should do and is safer for the frame. Be very, very carefully not to cut the frame here.

Then using a cold chisel or similar, knock the strip of seatpost that you've just created down into the rest of the seatpost. Once it's down a reasonable way (beyond the top part of the frame that grips) use a mole wrench or something similar to crush the seatpost. Extract.

It's not easy, and it takes a long time, but it will work.

Arthur - thanks for describing the method in full. Will give it a try later in the week & see how things go. Already have most tools at my disposal so just need to invest in the special saw (is it the same as a "keyhole" saw or something different entirely?).

Dave B