Stuck Seat post, but need to move the saddle - Shorter cranks?

Hey all,
I hope the festive season is being good to those who celebrate, and that peeps are keeping safe.

I have a bike fit question for those in the know. But a bit of a back story.
My saddle post appears to be stuck in my bike. Carbon fiber frame, aluminum seat post.

Having tried WD-40 through the bottle cage bosses and using a certain amount of elbow grease, it still wasnt budging.

I am going to contact a few LBS’s in the new year, but I am reluctant to spend over a certain amount as I dont think the bike is worth it.

The thing is, I only want to drop my saddle by about 5-10 mm :frowning:

Can I ask those in the bike fitting know how, if I can get my hand on on shorter cranks, and dont adjust the saddle height, I am in effect “lowering” the height?
I am currently running 175mm cranks, so going to 165, or 170 would have the desired 5 - 10mm drop?

I can get some shorter cranks off friends, so it may be worth trying if it is as simple as that?

This is purely just advise on the bike fit / crank length side of things for know. Any advice on that front would be appreciated.

Your assumption that shorter crank length reduces saddle height is correct. While I think it is strange to swap cranks because of a stuck seatpost I do see your point.

Also note that there might be saddles with less height depending on your current model.

I’d swap the crank and give it a test-ride before spending some cash.

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Hey Hannes,

Thanks for this.
Yes, it’s far from an ideal solution, however it may cost me nothing and may even work.
I fear the bike may be broken, but also do not want to spend a lot of money repairing it as it isn’t worth it at this stage.
I’d rather not dent the new bike fund if that makes sense?

Also, of it works, it can just stay in the trainer :relaxed:

Free the seat post off by pouring coke down the seat tube. Take the BB out, turn the bike upside down pour in as much as you need to cover the inserted part of the seat pin. If you leave the bike a day or two the post should free off. I’ve used this technique a few times and its not failed yet.


I would have suggest using icy water to cool and shrink the aluminium seatpost. Or maybe try a co2 cartridge.

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yeah, you need a mild acid. Good suggestion.

If it works free, make sure to grease your seat post or use carbon paste or anti-sieze. Corrosion is causing the sticky post. Also fully clean that seat tube. The grease is to create a barrier to avoid galvanic corrosion.

Hey SPS & Splash,
Thanks for those suggestions.
Tried the ice, and freezing spray. No joy

Haven’t tried coke however, so may have to give that a go.

I am not ruling out getting it repaired, however as said in the OP, there will be a cost benefit analysis that will have to be done. And with some free shorter cranks on offer, I was just throwing it out there.

Thanks for the replies though.

Yeah, completely didn’t realise this.
It it becomes free, then that will definitely become part of the routine maintenance!

The bond material is typically of an alkaline base. It can help to use a mild acid to weaken the bond, such as lemon juice or a cola such as Coke® or Pepsi®. Allow some time for the acid to work.


Unfortunately same issue for me, carbon frame with aluminium seat post. Trying to soak in some WD-40 from the top in between the cracks. The parktool page is pretty useful, will also try Coke later. If that doesn’t work, probably ask LBS if they have experience with it and are able to help.

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