Trying to free up a seat post on Alu frame

secman · 24-07-2018 08:16PM #1

As the title suggests, I'm trying to free up a seized seat post on an Alu frame. It was last adjusted 2 years ago... need to drop it by approx 1/2 inch (old money terminology) following a recent bike fit. Have tried WD 40 extreme to no avail

All suggestions are most welcome .

saccades · 24-07-2018 08:19PM

secman wrote: »

As the title suggests, I'm trying to free up a seized seat post on an Alu frame. It was last adjusted 2 years ago... need to drop it by approx 1/2 inch (old money terminology) following a recent bike fit. Have tried WD 40 extreme to no avail
All suggestions are most welcome .

Fit an old saddle, put into vice, spray more WD-40, try to turn the saddle using the frame as leverage.

Spray more WD-40.

Come back 3 hours later and repeat. Don't torque the frame too much.

secman · 24-07-2018 08:41PM

saccades wrote: »

Fit an old saddle, put into vice, spray more WD-40, try to turn the saddle using the frame as leverage.

Spray more WD-40.

Come back 3 hours later and repeat. Don't torque the frame too much.

Have used loads of WD40 and tried to twist the saddle... frame was warping. Have just come across a method using boiling water on frame to cause it to expand and pull away from seat post ?

Anyone have success with this method ?

saccades · 24-07-2018 11:12PM

You need time and lots of WD-40.

The boiling water trick is relying on different coefficients of thermal expansion... Better with a blow torch but you can kill the frame.

But time and WD-40 will work, I freed up a completely fused berg gokart steerer doing the same.

lizzylad84 · 24-07-2018 11:25PM

Second the wd 40. Had similar problem and took paitence

magicbastarder · 24-07-2018 11:28PM

What's the seat post made from?

GreeBo · 24-07-2018 11:29PM

Have you tried whacking it with a rubber hammer?
if you take the saddle off and hit down vertically on the post you can shock it free without damaging the frame.

secman · 24-07-2018 11:32PM

I'll persevere with the WD40 so, only get to that bike on weekends, might bring it back up to to douse it daily . 1/3 of a can on it thus far though !

I'll try the boiling water too though... a few Our Fathers and maybe a decade of the Rosary

secman · 24-07-2018 11:35PM

GreeBo wrote: »

Have you tried whacking it with a rubber hammer?
if you take the saddle off and hit down vertically on the post you can shock it free without damaging the frame.

Yep tried the rubber mallet

GreeBo · 24-07-2018 11:37PM

secman wrote: »

I'll persevere with the WD40 so, only get to that bike on weekends, might bring it back up to to douse it daily . 1/3 of a can on it thus far though !

I'll try the boiling water too though... a few Our Fathers and maybe a decade of the Rosary

Is the post also alu?

Either way, stick some ice packs on the post and some hotwater bottles on the frame and keep the mallett nearby.

secman · 24-07-2018 11:37PM

magicbastarder wrote: »

What's the seat post made from?

Looks like it's Alu too, pretty sure it is.

GreeBo · 24-07-2018 11:37PM

secman wrote: »

Looks like it's Alu too, pretty sure it is.

Thats not going to help the heating approach as both will expand at the same rate...

jimbobaloobob · 25-07-2018 01:22AM

secman wrote: »

Have used loads of WD40 and tried to twist the saddle... frame was warping. Have just come across a method using boiling water on frame to cause it to expand and pull away from seat post ?

Anyone have success with this method ?

Yes.
Also try coke. Though needs to soak

comanche_cor · 25-07-2018 09:06AM

Recently had a alu frame where the carbon post was stuck. Heat & Cold did not work for me. Dropped it into one bike shop and they did sfa - however, dropped it into an other and they managed to get it out. Said they sealed it off and poured coke through the bottom bracket...

jimbobaloobob · 25-07-2018 11:10AM

Coke works great I use it for people's shoes and cleats also. Takes all the junk out

secman · 25-07-2018 03:56PM

jimbobaloobob wrote: »

Yes.
Also try coke. Though needs to soak

Don't do coke though .. I can see why being hyper might help though..

.

See below another suggestion to use coke Cola...

CrowdedHouse · 25-07-2018 05:59PM

As an aside I found (Tec7) GT 7 has far better penetrating qualities than WD40

saccades · 25-07-2018 07:17PM

Coke is for steel, uses the weak phosphoric acid to passivate and remove the rust. Useless on aluminium oxide.

Plusgas is ace as a "freeing" agent but not seen it for sale in Ireland unfortunately.

magicbastarder · 25-07-2018 07:52PM

i known mercury eats through aluminium oxide, but at rate a little to slow to be of use. plus, it's probably not the most penetrating of liquids anyway.

GreeBo · 25-07-2018 11:21PM

An ammonia based drain cleaner should eat away the oxidation, similar to the coke method, pour in into an upside frame and leave for a few hours.

did you try the ice/heat trick?
Ideally your freeze the post for a while and then pour boiling water onto the frame and pull immediately (you want to do itbefore the post also heats up)

secman · 25-07-2018 11:43PM

GreeBo wrote: »

An ammonia based drain cleaner should eat away the oxidation, similar to the coke method, pour in into an upside frame and leave for a few hours.

did you try the ice/heat trick?
Ideally your freeze the post for a while and then pour boiling water onto the frame and pull immediately (you want to do itbefore the post also heats up)

Nah, not yet , that bike is down the country and is usually a weekend winter bike, will give it a go again this weekend.
Would using a co 2 cartridge on seat post be possible ?

GreeBo · 25-07-2018 11:51PM

secman wrote: »

Nah, not yet , that bike is down the country and is usually a weekend winter bike, will give it a go again this weekend.
Would using a co 2 cartridge on seat post be possible ?

Yep, you just need to be quick with whatever method you use.

If you have CO2 cartridges then Id try to heat the whole area first, then rapidly cool the stem and hammer/yank ASAP.

Because the are both ALU the heat will transfer quickly.

Ideally youd have someone else to thump/twist as you cool the post.

secman · 20-08-2018 05:58PM

Just a quick update.. left bike in for a front derailler adjustment, mentioned seat post issue to mechanic.... no problem.says he...super dooper stuff.. better than wd40 says he... no budge... heat says he...break the seal heating up and definitely when cooling down says he.... still no budge... twisting ... rubber mallet.... nada movement.. Undid ckamp and took bike off stand... big dent in crossbar

In fairness to him he said leave it with him...he would get crossbar fixed. .a mate using grabbers.

Got call this evening... crossbar is fixed and reprayed... has totally serviced bike, polished and buffed to an inch if it's life... just no mention of seat post

Collecting it later.. fingers crossed. .in a way I did have some pity for him as well as being pissed off, but he has remedied it.

Trying to free up a seat post on Alu frame

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