Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Damned seatpost...

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Damned seatpost...

Old 06-15-17, 08:01 PM
  #1  
asmac
Senior Member
Thread Starter
 
asmac's Avatar
 
Join Date: Aug 2011
Location: Toronto
Posts: 1,261

Bikes: Salsa Vaya

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Damned seatpost...

After four years I decided to raise the aluminum Thompson seatpost on my steel Vaya. I had, for some foolish reason, believed that the finish and machining on the seat post would prevent it from seizing and I was very wrong. It is utterly stuck.

I understand that a strong lye solution will dissolve aluminum while leaving the steel totally unaffected and plan to remove the bottom bracket and protect the paint with tape and a plastic sheet while dropping the lye solution down between the post and tube like penetrating oil. Goggles and gloves will be worn.

Does this sound like a reasonable plan? How long is the process likely to take? How sensitive is the paint (powder coat?)?

Any advice is appreciated.

And I have a tub of anti-seize ready if I'm lucky enough to need it for a new post.

Last edited by asmac; 06-15-17 at 08:07 PM.
asmac is offline  
Old 06-15-17, 08:07 PM
  #2  
fietsbob
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,599

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,339 Times in 847 Posts
Very FAQ... A plethora of past posts on that topic, I wont repeat them, look them up in the archived posts ..
fietsbob is offline  
Old 06-15-17, 08:58 PM
  #3  
asmac
Senior Member
Thread Starter
 
asmac's Avatar
 
Join Date: Aug 2011
Location: Toronto
Posts: 1,261

Bikes: Salsa Vaya

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by fietsbob View Post
Very FAQ... A plethora of past posts on that topic, I wont repeat them, look them up in the archived posts ..
Mea culpa. Should have checked. I have added a few questions to an earlier post.


This issue is causing me stress. I don't want to bugger it up.
asmac is offline  
Old 06-15-17, 09:50 PM
  #4  
corrado33
Senior Member
 
Join Date: Jun 2013
Location: Bozeman
Posts: 4,094

Bikes: 199? Landshark Roadshark, 198? Mondonico Diamond, 1987 Panasonic DX-5000, 1987 Bianchi Limited, Univega... Chrome..., 1989 Schwinn Woodlands, Motobecane USA Record, Raleigh Tokul 2

Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1131 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by asmac View Post
Mea culpa. Should have checked. I have added a few questions to an earlier post.


This issue is causing me stress. I don't want to bugger it up.
First do the reasonable things. Remove the bottom bracket, flip the bike upside down, and spray an entire can of PB blaster down into the seat tube. (Tape up any holes at the end of the seatpost.)

Let it sit there a week, refill if necessary. Come in EVERY DAY and give the seatpost many many tap taps from a hammer. All of the way around the seatpost from every angle. I bet if you let it sit there and do that long enough it'll come off.

When you're ready to take the post off, you can either drill a hole all of the way through it and stick something in there to twist while you're lifting, or you can just grab the post with a vice and twist the whole frame.

Come back and report then.

Start gentle, when that doesn't work then think about using lye.

Last edited by corrado33; 06-15-17 at 09:53 PM.
corrado33 is offline  
Old 06-16-17, 08:00 PM
  #5  
Kopsis
Senior Member
 
Kopsis's Avatar
 
Join Date: Apr 2008
Location: St. Pete, Florida
Posts: 1,258
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 83 Post(s)
Likes: 0
Liked 1 Time in 1 Post
The lye won't work like penetrating oil. You have to get a large amount in there and dissolve the post all at once from the inside out.

The lye method truly is a last resort solution (no pun intended). I try everything else first (including the hacksaw approach).
Kopsis is offline  
Old 06-16-17, 08:25 PM
  #6  
3alarmer 
Friendship is Magic
 
3alarmer's Avatar
 
Join Date: Nov 2010
Location: The Big Tomato
Posts: 21,315

Bikes: old ones

Mentioned: 296 Post(s)
Tagged: 0 Thread(s)
Quoted: 24251 Post(s)
Liked 7,942 Times in 5,570 Posts
.
...PB Blaster is OK as a penetrant, but what I use now is a 50/50 mix of acetone (paint aisle) and ATF (auto parts aisle).

It's just better enough for stuff like this that it's worth mixing up and using.


The only other tip I have is to find someone with a large bench vise firmly attached to a solid post or workbench that is in turn bolted to the wall or floor. Remove your wheels, replace with either bare hubs or axles double nutted into the dropouts/fork ends.

Find at least one other person to help, and once you've affixed the end of the post in the vise in such a way that you have clearance to turn the whole frame, one guy pushes on the frame to twist it on the post, the other pulls on the frame in the direction away from the vise.

I have done 50 or 60 stuck posts for people at the bike co-op using this method, with only two or three failures. It's hard work, but well worth it if you can avoid the lye thing.
3alarmer is offline  
Old 06-17-17, 07:29 AM
  #7  
Bike tinker man
Senior Member
 
Join Date: Dec 2014
Location: Retired to Penang Malaysia originally from UK
Posts: 344

Bikes: My 1978 Raleigh from new, 1995 Trek, & constant changing & rebuilding of other bike projects.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 41 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
Originally Posted by 3alarmer View Post
.
...PB Blaster is OK as a penetrant, but what I use now is a 50/50 mix of acetone (paint aisle) and ATF (auto parts aisle).

It's just better enough for stuff like this that it's worth mixing up and using.


The only other tip I have is to find someone with a large bench vise firmly attached to a solid post or workbench that is in turn bolted to the wall or floor. Remove your wheels, replace with either bare hubs or axles double nutted into the dropouts/fork ends.

Find at least one other person to help, and once you've affixed the end of the post in the vise in such a way that you have clearance to turn the whole frame, one guy pushes on the frame to twist it on the post, the other pulls on the frame in the direction away from the vise.

I have done 50 or 60 stuck posts for people at the bike co-op using this method, with only two or three failures. It's hard work, but well worth it if you can avoid the lye thing.
Yes this topic has been covered several times in the past, my only addition to the above is with the bike upended I use an old saddle that you can find anywhere & clamp that as hard as possible in the vice to destroy it, (it may save you the seat post) then proceed
Bike tinker man is offline  
Old 06-17-17, 09:37 AM
  #8  
drlogik 
Senior Member
 
drlogik's Avatar
 
Join Date: Mar 2016
Location: North Carolina
Posts: 1,589

Bikes: '87-ish Pinarello Montello; '89 Nishiki Ariel; '85 Raleigh Wyoming, '16 Wabi Special, '16 Wabi Classic, '14 Kona Cinder Cone

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 607 Post(s)
Liked 316 Times in 193 Posts
Kroil.

drlogik is offline  
Old 06-18-17, 07:57 AM
  #9  
Retoocs
Junior Member
 
Join Date: Feb 2016
Posts: 130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
Likes: 0
Liked 16 Times in 13 Posts
Kroil is so effective, it'll even works its way out of its own sealed container. I have an unopened container with an oil ring around the bottom.
Retoocs is offline  
Old 07-21-17, 11:08 AM
  #10  
asmac
Senior Member
Thread Starter
 
asmac's Avatar
 
Join Date: Aug 2011
Location: Toronto
Posts: 1,261

Bikes: Salsa Vaya

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I chickened out and paid an experienced mechanic to do it. Well worth it. I really didn't want to mangle the frame and had a bad feeling...
asmac is offline  
Old 07-21-17, 07:59 PM
  #11  
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Posts: 7,908
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 844 Post(s)
Liked 461 Times in 262 Posts
Originally Posted by asmac View Post
I chickened out and paid an experienced mechanic to do it. Well worth it. I really didn't want to mangle the frame and had a bad feeling...
Toronto, huh? I just happened to be standing in Malcolm Munro's shop a few days ago when he was showing somebody a corroded seat post he had extricated from a frame. That wasn't you, was it?
Dan Burkhart is online now  
Old 07-21-17, 08:28 PM
  #12  
asmac
Senior Member
Thread Starter
 
asmac's Avatar
 
Join Date: Aug 2011
Location: Toronto
Posts: 1,261

Bikes: Salsa Vaya

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I can run but I can't hide. Yes. It was me. And it was a nice Thomson post. Broke my heart!


And describing Malcom as a 'mechanic' doesn't paint an accurate picture. What a remarkable place and talented, eccentric guy. I'm glad I discovered him.
asmac is offline  
Old 07-21-17, 08:37 PM
  #13  
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Posts: 7,908
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 844 Post(s)
Liked 461 Times in 262 Posts
Originally Posted by asmac View Post
I can run but I can't hide. Yes. It was me. And it was a nice Thomson post. Broke my heart!


And describing Malcom as a 'mechanic' doesn't paint an accurate picture. What a remarkable place and talented, eccentric guy. I'm glad I discovered him.
Well, I was standing between you and Malcolm when he showed you the post. It was the first time meeting the guy. I was there with a guy I'm helping with a project and we were there to pick up a battery bracket Malcolm is fabricating for it.
Dan Burkhart is online now  
Old 07-21-17, 08:52 PM
  #14  
asmac
Senior Member
Thread Starter
 
asmac's Avatar
 
Join Date: Aug 2011
Location: Toronto
Posts: 1,261

Bikes: Salsa Vaya

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
This is the shop we're talking about: Biseagal | Our History

Last edited by asmac; 07-21-17 at 09:01 PM.
asmac is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
NattyBumpo
Bicycle Mechanics
41
04-03-21 12:47 AM
0ne
Bicycle Mechanics
4
04-17-17 10:43 AM
12strings
Bicycle Mechanics
6
03-31-16 03:32 PM
RaleighSport
Bicycle Mechanics
8
02-21-12 07:10 PM
WeirdOddity
Bicycle Mechanics
8
04-01-10 09:12 AM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2022 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.