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Seat post jammed in. ugh.

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Seat post jammed in. ugh.

Old 08-25-14, 07:25 PM
  #1  
vtwinjunkie
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Seat post jammed in. ugh.

Hello all.
Just picked up an old Peugeot over the weekend and I rode it today to give it a good break in and see if it needed any adjustments before a longer ride I had hoped to take this weekend.

The only issue I can find is that It appears the previous owner may have jammed a seatpost in that was a tad large for this frame or so it seems....

After returning from a quick 2 mile ride to the store and back I realized that my seat heighth was a tad high for my leg stroke and I wanted to adjust it down a bit. the adjustment screw was hand tight so that was my first clue. I tried wd40 and a rubber mallet and then more wd40 and a hammer to the bottom of the seat post trying to force it out....as you can see from the pic the frame tube at the base of the seat post looks buggered almost as if the seat post was forced in. Does anyone have any clue as to how I can get this out?
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Old 08-25-14, 07:37 PM
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OK, let's start with the size. Your bike has a built in seat post diameter gauge built in. A correct fitting post has an OD the same size as the seat tube's ID, and is a zero clearance running fit. The slot was machined into the frame at zero load so it has (had) parallel sides. If the slot is flared open, or pinches closed more than 1mm or so the post is too large or too small accordingly.

If, as I suspect, the post turns out to be the right size, it's a classic of frozen aluminum post in steel frame. The remedy is a matter of degree, running from decent odds of freeing it with either ammonia, or a penetrating oil like Kroil, or PB Blaster. (search the internet for "frozen aluminum seat post in steel frame"). there are all sorts of voodoo remedies, some work, some don't and it's impossible to predict which will work best for you, so read a lot, then decide which god you want to say a prayer to.
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Old 08-25-14, 07:42 PM
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there is a pic of the bike.
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Old 08-25-14, 07:50 PM
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It's a nice bike, and well worth what it will take to remove (possibly destructively) the seat post.

BTW- I forgot to mention that the paint chips at the top of the seat tube don't in and of themselves mean anything. One thing you might do, is run your finders down the upper part of the seat tube and see if you can feel any ripples or other evidence of the tube being forced wider.

If not, you're in good shape, and WILL be able to get the post out and restore this to it's former glory.
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Old 08-25-14, 07:52 PM
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Most likely FB is correct. Measure the seat post with a pair of calipers. Someone here may know if it's the correct size for that bike. Be exact. Sizes vary by parts of millimeters.
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Old 08-25-14, 11:53 PM
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You can also use a sawzall to cut the seatpost. Cut the top off and make sure you have a blade that will extend to the bottom of what's still in the frame.

Make a couple of parallel cuts in an arc 1/2 to 1 inch wide. Angle the blade so that it is cutting at the far end. You want to avoid cutting the frame and are much less likely to do so if the teeth of the blade are nearly parallel to the tube. If you it right, your cut will create a domed surface and you can crack the remaining seatpost thickness by punching that wedge out. Once you get the strip out, you should be able to free the post.

I've done this several times. Most recently several days ago. But it should be a last resort and you can search for the ammonia or big vice methods. I usually jimmy the top of the seat tube a little, but nothing serious.
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Old 08-26-14, 04:46 AM
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After applying penetrating oil for a few days with no results you may want to try removing the wheels and gripping the seat-post in a LARGE vise. Now use the frame as a lever to twist the seat-post free.
Good luck.
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Old 08-26-14, 06:36 AM
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WD40 on a stuck seat post is IMO sending a boy to do a man's job. Get yourself some Kroil (best) or PB Blaster and apply it generously. Striking the sides of the post ONLY (NOT the seat tube) smartly with a hammer a few times will help shake things up. Do this periodically along with more applications of oil. It may take some days for the oil to do its magic of creeping into microscopic spaces. Gentle heat like leaving the bike in a hot car may help too. Then try the "big vise" approach. Only after giving plenty of time for penetrating oil to work do I proceed to sterner measures. Patience and brute force are your friends.
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Old 08-26-14, 07:28 AM
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Kroil, time (worst case was allowing to soak for a week) and heat with gentle twisting so as not to bust the seat stays. I have also wedged the tangs apart slightly to allow the kroil to penetrate down the tube then released them. If you want to do it right, open the BB and apply from below. Hack saw is last resort.
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Old 08-26-14, 08:04 AM
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Originally Posted by SJX426
Kroil, time (worst case was allowing to soak for a week) and heat with gentle twisting so as not to bust the seat stays. I have also wedged the tangs apart slightly to allow the kroil to penetrate down the tube then released them. If you want to do it right, open the BB and apply from below. Hack saw is last resort.

Thanks to all for the great advice. This is my first classic bike (I have a new trek madone and a trek stache Mt bike that I ride weekly ) so I am not familiar with the older stuff .
I have had good luck with kroil in the past working on old motorcycles.
Bicycles seem so fragile in comparison and I wanted to ask you all before doing anything drastic.

I am very pleased to hear this is a common occurrence. I will look at it some more this evening.
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Old 08-26-14, 08:47 AM
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welcome to the annals of stuck posts .. you can re read the many other archived conversations .. sometimes the force to get the post out,

breaks the brass holding the seatstays on ... then you reBraze & paint.
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Old 08-26-14, 10:27 AM
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Originally Posted by fietsbob
welcome to the annals of stuck posts .. you can re read the many other archived conversations .. sometimes the force to get the post out,

breaks the brass holding the seatstays on ... then you reBraze & paint.
Oh that sounds awful..I will try the kroil and slide hammer approach. I am in no rush to break anything!
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Old 08-26-14, 10:52 AM
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Well for this classic I have found that PB blaster or other good penetrating oil and patience after the first try apply thoughely then wait a day or two then place the post snuggle in a shop vice and use the whole bike frame to pull and turn.
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