My girlfriend's signed us up for a disgustingly long audax next month, but my road bike's been rather neglected over winter in favour of the hardtail MTB. I've spent this week fitting new bars (so i can run my garmin and exposure race light together), new cables all round, new chain, cassette and cranks, bb, and serviced the pedals and the rear hub. All done and dusted and I go to ride the bike up and down the street. New cranks are 2.5mm longer than the old, so I need to lower the seat a tiny bit. I go to do this, and oh dear, the alloy seatpost has welded itself in to the steel frame... Embarrasingly this isn't the first time this has happened to me, had to take a frame to Argos cycles in Bristol for the same reason before!
Fortunately I live round the corner of Vernon Barker in Sheffield and Dave in there had it turned around in about 3 hours, despite him saying it's the worst he'd ever seen. It'll need repainted but I'm having it back so I can ride tomorrow and then Dave's kindly going to repaint it for me next week. Would highly recommend these guys for any of these sort of things if this happens - they've also redished/trued wheels for me before that I've done my best to wreck but they're still spinning as true as ever!
He recommended cutting the seatpost down to leave only 100mm in the frame to make it easier to get out if this happens again - I've measured twice and cut it down to leave 110mm in there - I've done this in case I ride up Snake Pass tomorrow and realise I need the saddle a tiny bit higher.
What would people recommend putting on the seatpost to prevent this happening again? I've put lithium grease on it for now as it's what I have to hand. It'll be coming out again to be painted next week so I could put something else on if STW hivemind thinks there's something better.
Thanks in advance
Copper slip works as well, and is possibly slightly more resistant to rain etc.
Best solution is taking it out yearly for a clean.
Lithium grease is fine. Just remember to move it every few months. And switch it to a quick release seat colar if you're lazy, to make it a 2 minute job to do
Just make sure you remember to remove it and clean it every 3 months before it has time to bond. But it's easily forgotten about.
It's easily done - I've been trying to remind myself for the past 4 weeks to remove & re-grease the alloy post from a Reynolds tubed frame, but life gets in the way. Silly really, but I'm determined this thread will help me get that sorted this weekend.
Hope the paint job turns out well OP.
Thanks all, thanks especially for the kind comments. Checked all the other steel bikes in the house and only one of them is seized - an unfashionable 15 year old xc frame destined to live out it's days as a commuter, which saddle heights already set at the perfect height. At least I don't need to take any more bikes down there with my tail between my legs! Reminder set on phone for 6 months time to check them all again
If the paint is damaged was it moved by heat? If so try freeze spray next time, plumbers stuff from jewson etc. And a few weeks with penetrating oil
And it’s not just alloy and steel. Had a close one with an alloy dropper post almost getting jammed in to a carbon frame. Took a lot of wd40 and a few plumbers wrenches to break the bond.
Copper, aluminium and water is a mix very susceptible to galvanic corrosion so maybe not copper based greases. But I suppose a disappearing seatpost means it won't stick to the steel.....
I actually had a crater form in the middle of an aluminium steerer tube. It was on an experimental home made frame I did with a top tube that pierced into the head tube (rather than mitred onto the outside of the HT). There was an internal fillet of brass very close to the steerer which coincided with where the crater formed. Had a chat with a metallurgist and he concluded it was the copper in the brass plus water and grease causing galvanic issues.
Took some photos. Blob of brass circled and crater that formed adjacent to it (but they never actually touched and there was no rubbing or scoring of the steerer).
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Op
You reminded me to check the seatpost on my nice bike was not seized so thats a good thing - ta
We’re all old right? And not growing any more?
So if the seatpost is in the right place, is seizing such a bad thing?
[Ducks and runs]
It's usual on this type of thread for me to nip out,check the seatpost and regrease it.
… does aluminium seize in titanium?
It’s happened to me on a carbon frame and a steel frame, and a fork in a steel frame. Don’t want that to happen in my Ti!
How long was it in there for? You've reminded me I have an important job to do lol
I think I'd last got it out about a year ago, maybe a bit more. Might not have put any grease on the last time which would have cause the problem...
So if the seatpost is in the right place, is seizing such a bad thing?
It is when you get longer cranks and therefore need to lower the seat...
Copper, aluminium and water is a mix very susceptible to galvanic corrosion so maybe not copper based greases.
Hmmmm. I copper slipped an aluminium seat post into a steel frame about 25 years ago.
I'm more worried about fatigue failure than corrosion... The frame and seatpin have probably done 200000km.
The idea is to electrically separate the two metals. Both anodised and painted surfaces will corrode because the coating is permeable (some are better than others).
Grease fills the gaps but it won't last forever. An annual check works for me but salt from sweat/winter roads makes things worse
Generally (varies with the electrolyte solution) the closer together the metals are in this table the better https://www.celcoinc.com/galvanic-compatibility-chart/
Graphite is included in the table and it's a good distance from aluminium so a CF frame and CF seatpost would be more resistant
… does aluminium seize in titanium?
Varies with the electrolyte solution, but yes
Oh. Don't get me wrong. I know the principal, but the posts still not seized or noticeably corroded...
If the seat tube takes a larger diameter seat post, fit a 27.2 mm seatpost with a shim. Put lots of grease on the inside of the seattube/outside of the shim. Leave the seatpost and inside of the shim dry. If the shim bonds to the seatpost, you can still remove them together and pry the shim off.
Shirley there must have been a pedal option that had ~3mm more stack? 😉
I remembered* to do it today. Job jobbed, and as a bonus I noticed the rubber strap on the rear light was half snapped - so probs would've fully snapped off on a commute home next week, bouncing off into the undergrowth flashing away like a deviant in a dirty raincoat.
* I didn't, I just saw the Post-it I left last night as a result of this thread.
If you do get stuck again google the seatpostman.
He has saved many a bike, including mine.
Thought I'd use this prompt.
Just lubed the seatpost on the road bike.
@mert not specific to you, general interest having made the "seat pin's anodised, what can possibly go wrong?" error 🙂
Think the black anodised Thompson post in my MTB is seized solid in my steel MTB. Ho hum.
Will have a proper go tomorrow but I suppose it’s one less thing to creak.
Oddly the seatpost in the steel hybrid of doom which gets neglected much more isn’t.
So, it’s not seized completely in that I can twist it. Should it come out with a bit of persuasion?
Not ridden my Unit in a long time, the seat post was on the verge of being seized.
Surely the OP would of been ok with thicker socks?
So, it’s not seized completely in that I can twist it. Should it come out with a bit of persuasion?
Two. Hours. Of BFI and penetrating oil. Came out though…
So if the seatpost is in the right place, is seizing such a bad thing?
TBH, crank height is a minor thing, i bet thats less than 5% of the "keen cycling population" swap crank lengths.
Pedals is more, but saddles with different stack heights... That must be a nightmare.
TBH, i hope the seatpost in have in the on-one i have seizes, so i can justify throwing the piece of junk in the bin.