Had an alloy seatpost seized in a steel frame which brute force just wasn’t budging and despite not being one for patience or belief in anything over brute force and/or mechanical means I decided I’d give basic chemistry a chance as a last ditch effort.

Slid the seat collar up the post and doused the top of the seat tube at the seat post junction with penetrating spray. Not WD40 or GT85 which are lubricants or water dispersants but Penetrating Spray. I believe the active chemical in drain unblocker (diluted) also works. Anyways, I doused it 2 or 3 times a day, sometimes more, for 4 days straight. Tonight, grabbed the saddle with frame between my legs and managed to free it without too much diifficulty. Hoorah.

This seat post was seriously seized, it wears the scars from where I used grips to try twisting it previously. When I did get it out, it was covered in dissolved rust, and still has rust spots on the alloy. However, it is still perfectly serviceable and will be greased and go back in….and be more regularly greased in future.

Thought I’d share my experience and hope it helps others. Remember, not WD40 or GT85, they’re (arguably) good at what they are but they are not penetrating sprays. In my case I used WD40 brand Specialist Fast Release Penetrant acquired from Halfords.

I’ve done the same with a product called Plus – Gas. I did it in turn from the top and the BB area beneath turned upside down.

GT85 is actually a pretty effective penetrating spray- not far off Plusgas which is the daddy. (to quote an RAC chap I spoke to “It’s 90% as good as plusgas but it costs 10% as much so I can use 50% more”. That’s proper maths and everything.

(WD40 does work too- yes it’s designed as a water disperser but it’s not far off being a tin of white spirit and mineral oil. Not the best at the job though. Personally I think it just makes sense to get something better, good penetrating oil can be the difference between an easy job and a bollocks… But don’t write it off. It also kills the scottish midge)

Diesel’s good if you can get it soaking- for seatposts, sometimes they’re well enough sealed with dirt, corrosion and interference that you can turn it upside down and pour some in, you’ll know it’s worked when you come back and the floor’s covered in diesel. For small parts, chuck em in a jar.

I believe the active chemical in drain unblocker (diluted) also works

Many drain cleaners contain strong sodium hydroxide (caustic soda) solutions, which would be good at dissolving greasy crap but wouldn’t do much to steel corrosion products and will irretrievably damage aluminium alloys. I’d be cautious about this one, without knowing what drain cleaner and on what it was used.

Atf and acetone is the penetrating fluid of kings.

Gt85 proven its self about as effective as piss in the past.

I tried the same to get my hilo out of my 456. Also poured loads of boiling water on the seat tube.
Didn’t matter what I did, couldn’t get it to rotate.
Ended up using a stilson and scaffold pole on lower part of seat post, and believe it or not, this is not good for hilo’s.
My own fault for not moving the seat post for a year, and I don’t suppose riding on the beach helped much.

WD-40…also kills the scottish midge

How does this happen? Do you spray them one at a time with the straw, or loads at once with the spray? 🙂 ❓

was covered in dissolved rust, and still has rust spots on the alloy. However, it is still perfectly serviceable and will be greased and go back in.

The worst ones are covered in aluminium oxide, I doubt yours was that bad.

Wd40 would kill any midges surely ? And to think of it any insects ?