I have a carbon seat-post which is stuck in a TITANIUM frame.
There is a chemical reaction that causes this but I don’t know what it is. Can anyone suggest how to remove it?
It’s not caused by rust (steel frame) or galvanic corrosion (alu frame) or carbon-to-carbon bonding (carbon frame), rather the carbon-titanium interface is something else - but I don’t know what, so I don’t know how to resolve it and extract the seat-post.
Any suggestions specifically for CARBON-TO-TITANIUM seizure?
Thank you for specifying carbon post. Any material can get ‘stuck’ due to corrosion and what not - this is not your issue. Ti to Ti can effectively weld itself together…as you know, not your issue.
I once had that with a Litespeed and a Campagnolo Carbon seat post. Put some PB blaster at the top and bottom of the seat post (via the hole in the BB shell to the seat tube). Give it a bit, if it needs more assistance you can put hot (boiling) water on the seat tube (not the post) and the metal should expand a bit and allow you to gently twist out the post.
There is a possibility that an alloy sleeve is in the seat tube of the titanium frame, and that could cause galvanic corrosion.
Another possibility is that the seatpost was greased a long time ago, and some greases cause carbon fiber to swell which could cause the stuck scenario.
Either way, biggest thing is you’ll need is as mentioned above some sort of penetration solution and leverage. Ideally secure the seatpost and then turn the bike, as that will give you a greater force multiplier.
Not sure this will work with Ti/Carbon but I’ve used this with Carbon/Carbon, Carbon/Aluminum, and Aluminum/Carbon. Take a can of compressed air and turn upside down or buy a can of Freeze off and spray the post/seat tube liberally (do not touch them) then try and pull the seatpost out. It’s worked for me based on the idea that the materials contract at different rates at extremely cold temperatures. I always use a generous amount of Carbon Grip in the seat tube regardless of materials, prevents bonding and slip.
Just a PSA, Never use Carbon grip on a steerer or inside your steerer, the grit can seep down into the headset prematurely wearing the bearings or worst case acting as essentially a saw blade on the steerer tube around the bearing race. On the expanders it will often prevent the mating surfaces from getting grip and actually induce slip (found this out recently.
I’d remove the chainset and bb, turn your frame upside down, and pour coca-cola into the seattube via the bb. Let it sit overnight. That may well loosen it up enough to be freed off with some twisting.
Warm up the seatbolt area with a hairdryer or boiling water, then while it’s still hot, shoot some freeze spray up the seattube from the bb. Try to remove.
Both of these methods are worth trying a few times if you have the inclination.
If these fail, you’re looking at cutting it out, which will obviously destroy the post, and is probably a job best given to a shop - if you can find one who’ll take it on. The risk of damaging the frame is not zero, so many will either refuse, or ask you to sign a disclaimer.
and if everything above fails to deliver - cut the seatpost +/- 10mm above the end of the seat tube and then slice the remaining carbon tube once or when necessary twice - 180 degrees displaced and be aware not to harm the titanium
ENGINEER tz-02 Handy Handheld Saw (Hacksaw Blade Fitted into a Plastic Handle), Black/Blue
If going that route, a blade made for carbon would be a good choice. Those are made to abrade the carbon and should be less likely to scratch the seat tube up. I’d still use an abundance of caution though.
What is PB blaster? Not familiar with it.
Good tip (with reasons) about why not to use carbon paste on stems. Thank you. Most stem guides day don’t without giving any reason.
Do you assembly dry, or use copper assembly paste? Cheers!
Is there a frame builder on the forum? He might tell you what not to do with your frame in terms of heat and cold. If heat/cold is no problem I’d try that route. Seems the least destructive.
If and really if sustained heat is no problem and the thing is really stuck I’d saw off the post until a few inches and then heat the frame around the stuck seatpost with a heat gun.
Perhaps in conjunction with a Dremel.
Otherwise: set the post on fire. I’d do this outside, otherwise it’ll upset the misses.
Carbon specific blades are made with carbide abrasives and are thus more likely to damage the titanium tubing (although it isn’t hard to cut Ti with a tool steel blade so it’s just a matter of degrees).
I’d also advise caution when cutting carbon composites: the dust is really quite nasty.
FWIW trying to chill the carbon composite seatpost won’t work, the fibres in the hoop orientation constrain the thermal expansion of the post (carbon has essentially zero CTE in the fibre direction).
If this problem were presented to me I would try putting the whole frame and post in the oven and heating it to about 150 oC. This will cause the Ti to expand and should soften the epoxy in the composite post enough to make it removeable.
If you have someone local with an oven big enough to take a bike frame this would be worth a try.
Are you sure that the carbon is stuck to Ti? Maybe it is worthwhile to investigate whether the frame has an aluminum seattube insert, which may complicate things even further.
You could try Carbo Move .
I haven’t used it , but it seems it is designed for this type of problem.
It is for breaking bolts and what not free - any autoparts store.
Thank you for the explanation. Cheers!