Seat post stuck

Nabber

Hey guys

I tried to adjust the seat on mt bike. But the seat post wont move. I have given it a good spray of WD40 for the past 5 days and nothing.

I gave it a few taps of a hammer to se if I could loosen it up, still nothing.

I tightened a vice grips to it, but the metal of the seat post just gaveway before the seat post would move.

Really at wits end with this. The saddle is just 3inchs to low for me to be comfortable while cycling.

Any help would be great guys.

Cheers nabber

Raam

Whack it with a hammer instead, on the saddle.

Nabber

The saddle pops onto the seat post.

So the sadle will just come off.

Don't wanna damage the saddle

Raam

pops on?

I've had a stuck seat post and wrenching on the saddle was the only way to get it out.

seamus

Nabber wrote: »

The saddle pops onto the seat post.

So the sadle will just come off.

Don't wanna damage the saddle

Older/cheaper bikes have "two-piece" seat posts which have a clamp at the saddle which is removable from the seat post (effectively making your seat post a bit of pipe). If this is tight enough, the saddle won't come off and hauling on the saddle is the best way of loosening the seat post.

Have you tried loosening the bolt at the *bottom* of the seat post, where it enters the frame?

fenris

You have tried the gentle way and it didn't work, some of the options are:

1. Take off the saddle, flatten the top of the seat post with a hammer to give you a better grip.

2. Turn the bike upside down, place the now mangled end of the seat post into a vice and use the bike as a lever to twist the seat post free (health warning if it is an expensive bike)

3. cut the top off of the seat post and VERY carefully hacksaw out a vertical section of the seat post without cutting the frame, then crust the seat post with a vice grips and remove.

4. Bring it to the bike shop and see if they can sort it out

5. View it as an excuse/justification to go bike shopping and create a "what bike" thread

Sheldon has some ideas.
http://www.sheldonbrown.com/stuck-seatposts.html

tomasrojo

If you do get it out, grease the seat post before you re-install it. Fusing of the frame and seat post is really common. Re-grease it every year or two years.

cipo

Had this problem on a bike previously too... Not my bike I might add!!

Couldn't leverage it free with a vice, tried removing bb and used jeyes fluid no effect!!!!!

Had to hacksaw post and slice vertically into it..... Time consuming but ultimately satisfying in the end!!!!

Be careful especially with carbon frame....

Try LBS first....

Good luck with it.....

Nabber

How does the hack saw method work?

Not sure if I quite get it.

cipo

Start by cutting thru seatpost with saw horizontally an inch to two inches above seat stay / seat post collar!

Once that's done you can see right down into your seatpost!
With a small filing saw SLOWLY saw vertically into seatpost from inside to out!

Idea being that when you cut a large enough slot away from post you can compress the post to create more room within seatstay to allow seatpost to come free.

It takes time ..... But it's safe enough for the the frame obviously seatpost will be totalled but frame can be saved!!!

IM0

substitute the word seatstay for seatpost no? ^
I see what he means, dodgy but as a last resort why not.

cipo

Just reread it... Makes sense to me but it's a bit of a confusing matter with silar terminology!!

Seatpost is a seperate component on to which saddle sits, compared to the seat stay... part of the bike into which seatpost is clamped.

Only thing damaged with this method is the seatpost and you can buy a new one!

kona

What bike is it and what seatpost is it?

I think you may need to drill it out, and by drill I mean bring it to a engineering shop, they will be able to drill out the seatpost precisely.

SubLuminal

Is one aluminium and the other steel? If so you may be totally screwed, if installed without grease the alu will oxidise and you prolly won't be able to get it out. You could try the vice method, come into Rothar with the bike and we may be able to get it out for you using our tools, but in the past i've come across bikes with the same problem that we just couldnt fix economically (eg we can't spend ages with a saw taking out a vertical section)

Put the bike upside down in a vice and use the frame as leverage to try and unstick it, if it doesnt work you're left with getting used to it or doing what someone else said re. drilling it out or the vertical cut..

seamus

cipo wrote: »

Seatpost is a seperate component on to which saddle sits, compared to the seat stay... part of the bike into which seatpost is clamped.

Pedantic, but the seat tube is the part of the frame that the seatpost clamps into. The seat stay is the upper part of the rear triangle - on hardtails, the seatstays are the part of the frame which connect the seat tube to the rear dropout.

kona

FWIW, It is possible to rip the seat off the seatpost, ive done it before in a situation as above, it makes things waaaay worse.
OP, If it wont budge in the vice forget it, youll just twist and break a AL seatpost. You gunna have to drill it out.

doozerie

Something acidic like lemon juice or Coca-cola are supposed to be useful in breaking down the bond between the seat post and seat tube. It'll be tricky to get it to run into the joint, and it'll take time to work if it is going to work at all, but it's certainly worth a try.

Swinging out of the saddle risks destroying the saddle itself. Too much enthusiasm with a hammer, or a vice grips or similar, can put too much strain on the wheels. Whatever approach you take, beware of damaging other parts of the bike in the process.

Nabber

I don't mind destroying the saddle. It's a very unforgiven saddle.

I try a few of the tips mentioned.

If the aluminum and steel have fused, would this be as strong as a weld?

kona

Nabber wrote: »

I don't mind destroying the saddle. It's a very unforgiven saddle.

I try a few of the tips mentioned.

If the aluminum and steel have fused, would this be as strong as a weld?

Yup cold welded.

Golfanatic

use bleach if its an alu seatpost pour it thriugh the bottom bracket not just the seat collar ammonia brakes down the alu oxide

CramCycle

Drill through it with a large drill bit and put a rod through and try to screwdriver it out. Obviously the seat post would not really be great to use again. Pretty much the same idea as clamping it in a vice and twisting the bike around.

Gavin

consult the pro

http://www.sheldonbrown.com/stuck-seatposts.html

pmcd22

I read a few posts on different sites about the hot and cold technique.

Heat expands the aluminium and then the cold shrinks it. Doing this a few times should cause the two metals to break apart slightly. Then into a vice grip and a big twist it.

http://www.youtube.com/watch?v=wUzFj2K8Ti4

Anyone ever try this method?

techieelectric

Yep have tried the blowtorch one, I think it worked eventually but in combination with other things. putting the saddle on incredibly tight and hitting it with a lump hammer from side to side would be the first option for me, especially if you've got a saddle you don't mind wrecking. after that stick it in the vice and if none of those work proceed to more drastic measures. If it's an aluminium post ammonia works well in getting rid of alu oxide which I'd try before cutting/damaging the seat post. It can be gotten easily from a hardware for a few quid.

If it's aluminium in a steel frame you can always dissolve it with caustic soda, nasty but effective. Just be very sure it's not an alu frame first.

kona

pmcd22 wrote: »

I read a few posts on different sites about the hot and cold technique.

Heat expands the aluminium and then the cold shrinks it. Doing this a few times should cause the two metals to break apart slightly. Then into a vice grip and a big twist it.

http://www.youtube.com/watch?v=wUzFj2K8Ti4

Anyone ever try this method?

The only times I have used this method was to remove the balljoints on a 20 year old car, and to remove gunbarrel piping that was seized, both messy jobs, both took ages and a job I really really dislike doing.
In the case of the balljoints and piping both are made from mild steel, and both were being replaced with new.
Heating up and metal messes up the atomic structure, hence why they expand, IMO the aluminium of bikes is far to thin and the grade isnt strong enough to resist this, in other words Id expect to damage the bike more.

Much safer to either cut a wedge out or drill it out. The only reason this happens is because people dont grease things, I grease everything thats in metal to metal contact.

kona

techieelectric wrote: »

Yep have tried the blowtorch one, I think it worked eventually but in combination with other things. putting the saddle on incredibly tight and hitting it with a lump hammer from side to side would be the first option for me, especially if you've got a saddle you don't mind wrecking. after that stick it in the vice and if none of those work proceed to more drastic measures. If it's an aluminium post ammonia works well in getting rid of alu oxide which I'd try before cutting/damaging the seat post. It can be gotten easily from a hardware for a few quid.

If it's aluminium in a steel frame you can always dissolve it with caustic soda, nasty but effective. Just be very sure it's not an alu frame first.

Might be talking out my arse here but is ammonia not explosive in gas form? surely it wouldnt be smart putting a blowtorch on it?

Karma

bring the bike to city cycles on blackhall, they will get it out. sometimes with this messy stuff is best to leave it to the experts.

techieelectric

kona wrote: »

Might be talking out my arse here but is ammonia not explosive in gas form? surely it wouldnt be smart putting a blowtorch on it?

I don't know, the one time I used ammonia it worked so that was the end of it, I'll look into it and keep that in mind for the future though.