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Stuck seat post question

Old 08-31-21, 10:15 PM
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Nishiki89
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Stuck seat post question

I picked up a vintage Schwann Le Tour for $30 for the purpose of converting to a gravel/commuter/beater/kid hauler. Itís got a badly stuck seat post, go figure. Itís an aluminum post in a steel seat tube. Iíve failed to remove it by twisting or hammering, and Iíve started to saw it to no avail (it cuts but seat post walls a extremely thick and this hasnít allowed me to roll it out). Iím slowly (and cautiously) coming around to the idea of using lye. My question is, is it essential to remove the bottom bracket?

I ask because Iím not sure if there are any non-steel materials in the bottom bracket that would be exposed if I poured lye down the seat tube. Note, there are no water bottle mounts on the seat tube, so that is not an option. If I leave the bottom bracket in there will it be damaged by lye?
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Old 08-31-21, 11:09 PM
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Assuming you have been trying different methods but to no avail. Before going to lye you should try CRC Freeze-off. Or try Liquid Air used for cleaning key boards only hold the can upside down to spray the post with Trifloroethaine.
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Old 09-01-21, 06:51 AM
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I can't imagine going through the lye process and not cleaning out the BB afterwards, so I'd remove it.
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Old 09-01-21, 07:08 AM
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Most likely the BB shell is open to the seat tube, vented with a hole or the lug socket. So either the vent has to be plugged to keep the lye from just draining out or the frame will need to be dunked into a container of lye upside down.

I agree with andrewclaus in wanting to clean and grease the BB, even if no lye was used the BB will benefit from servicing. To answer the narrow question- it's likely that the BB is only steel and maybe some plastic. Andy
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Old 09-01-21, 09:24 AM
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Well when I did it I had to pour through the BB so yeah I removed it.
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Old 09-01-21, 04:26 PM
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Try using the 50/50 acetone and atf mix and let it sit upside down for a few days. The mix normally allows a post to come loose. Smiles, MH
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Old 09-02-21, 09:10 AM
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I would use a sawsall and just carefully cut parallel to the seattube, use a "wood" blade if you can. A couple of things will happen, the blade sounds different on the steel and you will get a puff of a galvanic corrosion. If the post is real thick I'll make two cuts. At that point you can probably snap the grove cut and pull or fashion a slide hammer to help break the bond. I'm sure that you have been using a PB Blaster already.

My last stuck seat post was 8" of insert, I had to buy really long blades for the sawsall. I cut two grooves one all the way through, and made a slide hammer from threaded rod a 1/2" socket and nut to hold the socket on the rod.
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Old 09-02-21, 06:45 PM
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I've had some success on this kinda thing, by:
1. remove BB
2. Put bike frame upside down
3. Spray liquid wrench down the sides of the seat tube - that assuming that the seat tube is accessible from BB - I don;t know anything about Schwinn LeTour...
4. don;t overdo the Liq Wrench, make sure it goes onto the tube walls, spray enough for it to migrate all the way down.
5. Let stand for a day, upside down.
6. Next day, apply Liquid Wrench again - a lot of the first application will not reach all the way down and will coat the entire tube walls - but best is slow migration, so you don;t have it go past the post/seattube interface.
7. get hands on as large pair of visegrips as you can, get a 'lever'/breakerbar to attach to adjustment end of visegrips - gaspipe works a charm
8. secure frame in some fashion, upside down, grip the seat post with visegrips,
9. start trying to rotate the seat post, if you break it loose, work it a bit... then do the Liq Wrench application again , let stand overnight again
10, repeat until the seatpost spins easy enough to start a downward rotating extraction... Frame is still upside down.
Patience counts...
best of luck
Yuri
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Old 09-02-21, 07:23 PM
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Originally Posted by Mr. 66 View Post
I would use a sawsall and just carefully cut parallel to the seattube, use a "wood" blade if you can. A couple of things will happen, the blade sounds different on the steel and you will get a puff of a galvanic corrosion. If the post is real thick I'll make two cuts. At that point you can probably snap the grove cut and pull or fashion a slide hammer to help break the bond. I'm sure that you have been using a PB Blaster already.

My last stuck seat post was 8" of insert, I had to buy really long blades for the sawsall. I cut two grooves one all the way through, and made a slide hammer from threaded rod a 1/2" socket and nut to hold the socket on the rod.
What if we don't have a sawzall? Does anybody know of a jab saw type of tool that would hold a hacksaw blade? I have a stock seat post and a Fuji frame that has about six or eight inches of post inserted. I've tried ammonia, PB blaster ,and a 24 inch pipe wrench. No luck so far.
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Old 09-03-21, 06:34 AM
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Originally Posted by cyrano138 View Post
What if we don't have a sawzall? Does anybody know of a jab saw type of tool that would hold a hacksaw blade? .
A bare blade wrapped in electric tape on one end for a handle. Or something like this.

​​​​​​https://www.amazon.com/12-Inch-Bi-Me.../dp/B07GSK5JKX
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Old 09-03-21, 07:47 AM
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A sheet rock saw could do the trick.

Harbor Freight has very cheap power tools if you want to spend low. I'm not a big fan of Harbor Freight but they probably have a sawzall type for under $30. That's where I got my long blades for my last extraction.
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Old 09-03-21, 08:09 AM
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If you don't remove the BB, how are you going to pour the lye into the seat tube?

In any case, that's an extreme measure. A lot of people have good luck with PB Blaster, and as you're reading there are other products and techniques. Lye would be a last resort. And that's a dangerous process - it generates a lot of very toxic fumes.
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Old 09-03-21, 08:13 AM
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Cutting would be a last resort IMO but if it has to be done there are some that have attached a bow type of spring that goes the length of a bare hacksaw blade. I searched for photos but couldn't find any but I know some previous posters in other threads have included photos. The idea is that the bow provides the pressure against the blade leaving you with only having to draw the blade up and down against the seatpost. Makes the job faster and less tedious.

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Old 09-03-21, 08:26 AM
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Originally Posted by dedhed View Post
A bare blade wrapped in electric tape on one end for a handle. Or something like this.

​​​​​​https://www.amazon.com/12-Inch-Bi-Me.../dp/B07GSK5JKX
That's exactly what I was looking for, thanks. I hope the blade length is adjustable because I believe there's a bit more than six inches of seat post in there.
I'm not super invested in this particular frame but I'd like to give it a shot. It's an old Fuji Monterey I was going to convert to a fixed gear for my wife, but the paint is so bad that even if I get the seat post out I'll need to have it sandblasted or stripped somehow and repainted.
Thank you!
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Old 09-06-21, 05:21 PM
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Well, I got it. I used a lot of things but ultimately wound up buying kind of a hand saw that would fit down the tube and cutting and that worked pretty well. What got it loose in the end was putting it in a bench vise, cranking down as hard as I possibly could to tighten it, and then turning the frame.

Here's the weird thing though. It's a 27 mm seat post, they opening of the seat tube seems to be 27 mm, there was pretty minimal corrosion (though I don't have a frame of reference since this is my first stuck seat post removal), and it had grease on it. So why the heck was it stuck?

I guess it's possible the opening of the seat tube has been spread apart a little bit and this is like a 26.8 mm seat post or something like that. Does anybody happen to know what the Fuji Monterey with the valite 414 tubing seat post size is? 🤓


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Old 09-06-21, 08:16 PM
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....first, that's not pretty minimal corrosion. And I've removed a fair number of stuck posts over at the co-op.
Second, the only sure way to get the right sized post in there is to clean out the frame's seat tube, for at least the top foot or so, using some kind of brake cylinder hone or sanding it with abrasive paper wrapped around a form ( you can use some sort of pipe, or a smaller seat post than needed works well...you tape the abrasive paper on one end, and then roll it on. only sand in the direction that pulls the paper tighter. Then grease up you candidate posts and insert until you feel like you have a nice tight sliding fit.

In your case, I would guess your candidates are 26.8 and 27.0, but I 'm not there in the room. If you need to choose between a tight 27.0 and a loose 26,8, sand down the 27.0 one until it feels like the insertion portion slides well agains the sides of the seat tube.
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Old 09-06-21, 09:19 PM
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Originally Posted by 3alarmer View Post
.
....first, that's not pretty minimal corrosion. And I've removed a fair number of stuck posts over at the co-op.
Second, the only sure way to get the right sized post in there is to clean out the frame's seat tube, for at least the top foot or so, using some kind of brake cylinder hone or sanding it with abrasive paper wrapped around a form ( you can use some sort of pipe, or a smaller seat post than needed works well...you tape the abrasive paper on one end, and then roll it on. only sand in the direction that pulls the paper tighter. Then grease up you candidate posts and insert until you feel like you have a nice tight sliding fit.

In your case, I would guess your candidates are 26.8 and 27.0, but I 'm not there in the room. If you need to choose between a tight 27.0 and a loose 26,8, sand down the 27.0 one until it feels like the insertion portion slides well agains the sides of the seat tube.
Good advice, thank you! I will get on it.
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Old 09-07-21, 08:07 AM
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I recommend taking it to a shop and getting the ST reamed properly. Ask if they think going to a 27.2 size is OK as there are far more seatpost choices available in that size. Even if you keep it at 27.0 at least you'll know it's the correct diameter, will be perfectly round and the same diameter for the length of seatpost to fit into.
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Old 09-07-21, 11:35 AM
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Originally Posted by Crankycrank View Post
I recommend taking it to a shop and getting the ST reamed properly. Ask if they think going to a 27.2 size is OK as there are far more seatpost choices available in that size. Even if you keep it at 27.0 at least you'll know it's the correct diameter, will be perfectly round and the same diameter for the length of seatpost to fit into.
Worth a shot to see if any of the shops around me do this. There aren't a lot of great ones. Thank you.
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Old 09-07-21, 11:45 AM
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Originally Posted by cyrano138 View Post
Worth a shot to see if any of the shops around me do this. There aren't a lot of great ones. Thank you.
...you can buy a reamer on Amazon, and do it yourself, but it's more adventurous than the finer abrasive methods I mentioned.
Done correctly, it does produce a superior result, but I had the impression you were doing this on a budget.

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Old 09-07-21, 11:54 AM
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Originally Posted by 3alarmer View Post
.Second, the only sure way to get the right sized post in there is to clean out the frame's seat tube, for at least the top foot or so, using some kind of brake cylinder hone or sanding it with abrasive paper wrapped around a form ( you can use some sort of pipe, or a smaller seat post than needed works well...you tape the abrasive paper on one end, and then roll it on. only sand in the direction that pulls the paper tighter. .
https://www.woodcraft.com/blog_entri...ni-drum-sander
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Old 09-07-21, 11:58 AM
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Originally Posted by 3alarmer View Post
...you can buy a reamer on Amazon, and do it yourself, but it's more adventurous than the finer abrasive methods I mentioned.
Done correctly, it does produce a superior result, but I had the impression you were doing this on a budget.

The limiting factor here is more the cost-benefit ratio than the cost alone. It's a beat up valite frame from an entry level fuji. I'm sure it'll ride well enough, but I'm not sure if it wouldn't be easier to find a frame in better shape. I don't mind buying tools, but I try not to buy stuff I'm only going to use once. I think after my experience with this stuck seat post if I ever come across one again I'll probably just walk away from that bike rather than buy it.
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Old 09-07-21, 01:19 PM
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...I had pretty good luck with freeing them for people at the co-op, using ATF/acetone, and the bench vise/twisting the frame method that was finally successful for you. But I do remember one that was resistant to all my urging, and another one that gave way while ripping the top of the seat tube, right at the expansion slot. So I tend to check pretty carefully, before I invest in a bike with either a stuck stem or a stuck post. It's always a PIA, and on a small minority of frames, the cure kills them.

If you know you're gonna repaint the frame, there are very few stuck things that won't torch loose, but the original paint usually suffers.
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Old 09-07-21, 09:45 PM
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Originally Posted by 3alarmer View Post
.
...I had pretty good luck with freeing them for people at the co-op, using ATF/acetone, and the bench vise/twisting the frame method that was finally successful for you. But I do remember one that was resistant to all my urging, and another one that gave way while ripping the top of the seat tube, right at the expansion slot. So I tend to check pretty carefully, before I invest in a bike with either a stuck stem or a stuck post. It's always a PIA, and on a small minority of frames, the cure kills them.

If you know you're gonna repaint the frame, there are very few stuck things that won't torch loose, but the original paint usually suffers.
I appreciate that. I don't flip bikes or have a business or anything, and I know well enough how to put a seat post in my own bikes so that it will never get stuck..

I didn't try acetone. Just ammonia, liquid wrench, PB blaster, drilling, hammering, pounding, cursing, a few brief tantrums, hacksawing, and finally a bench vice.
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Old 09-07-21, 11:11 PM
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...it's a 50/50 mix of acetone and automatic trans fluid. You mix it up in small amounts, in some kind of small acetone resistant plastic bottle like an old Tri Flow bottle, with an application straw on the end to drip it where you want a penetrating oil. It's the best thing for taking apart old stuck stuff, like bicycles that have been together for a long time. Very useful for dismantling things without wrecking the parts beyond re-use.
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