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

corroded seatpost - got it out, what should i do to the inside of the tube?

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.

corroded seatpost - got it out, what should i do to the inside of the tube?

Old 02-10-06, 01:31 AM
  #1  
Senior Member
Thread Starter
 
Join Date: Sep 2004
Posts: 727
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
corroded seatpost - got it out, what should i do to the inside of the tube?

the seatpost


the tube


the post is obviously trashed. what should i do to remedy any problems with the inside of the tube?


note:it was greased, obviously not enough. this was after 2 months. could storing the bike indoors during winter have contributed?
zip22 is offline  
Old 02-10-06, 01:48 AM
  #2  
Senior Member
 
DannoXYZ's Avatar
 
Join Date: Jul 2005
Location: Saratoga, CA
Posts: 11,736
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 109 Post(s)
Liked 9 Times in 6 Posts
It's not that bad. Sand the seatpost lightly with oil and wet-n-dry sandpaper, 600-grit should even out that corrosion. On the seattube of the bike, spray some WD40 down there and run a brake-cylinder hone through for about 10-20 seconds:



Wipe everything off with clean rags. Re-grease seatpost and re-install.
DannoXYZ is offline  
Old 02-10-06, 02:25 AM
  #3  
Senior Member
 
spunkyruss's Avatar
 
Join Date: Sep 2005
Location: Hatfield, PA
Posts: 379

Bikes: '64 Schwinn Traveler, '73 Astra Tour de France, '79 Fuji Gran Tourer, '86 Dahon folder, '94 Specialized Hardrock, '95 GT Timberline, 2005 Jamis Aurora

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Storing the bike indoors may have been a contributing factor, but I doubt that it played a major role in your troubles. I would guess that water was thrown up from the rear wheel and entered the rear-facing slit of the seat collar, and was drawn down the seat tube. This type of water infiltration can generally be prevented by filling the slit with grease when you grease the seatpost.

It's a bit tough to tell from the picture, but the corrosion within the frame doesn't look like it will compromise the strength of the frame. It just looks like slight surface corrosion. It can likely be cleaned up with a rag and a wire coat hanger. Just cut and straighten the coat hanger, form a loop in one end, and then securely knot a small rag through though the loop of the coat hanger.

Some WD40 will help things along and allow the dislodged particles to stick to the rag for removal. Don't go crazy with the WD40, or you may thin the grease in your bottom bracket bearings.
spunkyruss is offline  
Old 02-10-06, 02:32 AM
  #4  
Senior Member
 
spunkyruss's Avatar
 
Join Date: Sep 2005
Location: Hatfield, PA
Posts: 379

Bikes: '64 Schwinn Traveler, '73 Astra Tour de France, '79 Fuji Gran Tourer, '86 Dahon folder, '94 Specialized Hardrock, '95 GT Timberline, 2005 Jamis Aurora

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
The seatpost looks like it can still be used if you clean it up. A scotchbrite pad (like you may use on grungy dishes) might work better than sandpaper, but use whatever you've got. It's really not that bad. At least you caught it after two months.
spunkyruss is offline  
Old 02-10-06, 04:10 AM
  #5  
Senior Member
 
Join Date: Jan 2006
Posts: 248
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Originally Posted by zip22
note:it was greased, obviously not enough. this was after 2 months. could storing the bike indoors during winter have contributed?
If grease didn't stop the rust, spray a load of dedicated rust inhibitor down the seat tube and over the seatpost.

highlyselassie is offline  
Old 02-10-06, 04:17 AM
  #6  
Senior Member
 
Join Date: Jan 2006
Posts: 248
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Originally Posted by spunkyruss
Some WD40 will help things along and allow the dislodged particles to stick to the rag for removal. Don't go crazy with the WD40, or you may thin the grease in your bottom bracket bearings.
TBH, I wouldn't stick WD40 down the seatpost at all, it's about 90% solvent with the tiniest bit of light oil thrown in. I don't why it gets so much mention as a lubricant, it's pretty pathetic even as a "jack of all trades".
highlyselassie is offline  
Old 02-10-06, 10:12 AM
  #7  
Senior Member
 
Join Date: Oct 2005
Posts: 5,820
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 383 Post(s)
Liked 133 Times in 91 Posts
Originally Posted by DannoXYZ
It's not that bad. Sand the seatpost lightly with oil and wet-n-dry sandpaper, 600-grit should even out that corrosion. On the seattube of the bike, spray some WD40 down there and run a brake-cylinder hone through for about 10-20 seconds:



Wipe everything off with clean rags. Re-grease seatpost and re-install.
Great idea! When I wrenched at a bike shop, we used an adjustable reamer, but the hone looks like a winner.
San Rensho is offline  
Old 02-10-06, 11:14 AM
  #8  
crusty
 
jbrians's Avatar
 
Join Date: Aug 2005
Location: Guelph, ON
Posts: 309

Bikes: Giant Kronos, Miele Appolo, Miele 12 spd, Diamondback Hybrid

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I have used a bore brush for a shotgun with some steelwool wrapped around the 12 gauge brush to clean out seat tubes. Remember, you don't need a mirror smooth surafce. I think a few pits in the surface will even help hold the grease a bit better.
jbrians is offline  
Old 02-10-06, 11:17 AM
  #9  
Senior Member
 
Join Date: Jul 2005
Location: Mid-Atlantic
Posts: 912

Bikes: A bunch

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Some fine grit sandpaper on a dowel ought to clear off the corrosion. Use plenty of grease when installing the new post.
CHenry is offline  
Old 02-10-06, 12:11 PM
  #10  
Senior Member
Thread Starter
 
Join Date: Sep 2004
Posts: 727
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
will cleaning off the corrosion on the post (as suggested above) be alright? should i worry about scratching off the anodization and having steel-aluminum contact? (hopefully with grease in between, but it seems like it would be a little easier for the corrosion without the anodization)
zip22 is offline  
Old 02-10-06, 12:56 PM
  #11  
Senior Member
 
Old Hammer Boy's Avatar
 
Join Date: Aug 2005
Location: Utah
Posts: 1,082

Bikes: Trek, Cannondale Tandem, Surly LHT

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
It's also possible, after all this junk is cleaned up, that there may be some nasty stuff down in the BB area. It depends upon whether the BB is bored through or not. Many are. You might be able to see that from the top of the seat post with a flash light. If it is, I would encourage you to pull the BB and clean it up, too. OHB
Old Hammer Boy is offline  
Old 02-10-06, 01:09 PM
  #12  
DocRay
Guest
 
Posts: n/a
Mentioned: Post(s)
Tagged: Thread(s)
Quoted: Post(s)
Originally Posted by DannoXYZ
It's not that bad. Sand the seatpost lightly with oil and wet-n-dry sandpaper, 600-grit should even out that corrosion. On the seattube of the bike, spray some WD40 down there and run a brake-cylinder hone through for about 10-20 seconds:



Wipe everything off with clean rags. Re-grease seatpost and re-install.
whoa. really dumb idea. Danno, I wish you would stop making thes types of suggestions without knowing what you are talking about.

You want to remove only the corrosion, not ream out the tube, that will weaken the tube and make proper seatpost fit impossible, ruining the frame.

LIGHT abrasive to remove any rust, then you can try a light coat of clear laquer to seal, make sure it dries for days, then a new seatpost with lots of grease.
 
Old 02-10-06, 05:56 PM
  #13  
Banned.
 
sngltrackdufus's Avatar
 
Join Date: Sep 2005
Location: tartarus
Posts: 1,258

Bikes: MTB's & a Cyclocross

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by DocRay
whoa. really dumb idea. Danno, I wish you would stop making thes types of suggestions without knowing what you are talking about.

You want to remove only the corrosion, not ream out the tube, that will weaken the tube and make proper seatpost fit impossible, ruining the frame.

LIGHT abrasive to remove any rust, then you can try a light coat of clear laquer to seal, make sure it dries for days, then a new seatpost with lots of grease.
A Brake cylinder hone will work fine if you stroke it right.It will leave a nice "cross hatch" pattern & hardly remove any tubing material.Just remember to keep the stones lubed.

Last edited by sngltrackdufus; 02-10-06 at 06:06 PM.
sngltrackdufus is offline  
Old 02-10-06, 07:04 PM
  #14  
Senior Member
 
Old Hammer Boy's Avatar
 
Join Date: Aug 2005
Location: Utah
Posts: 1,082

Bikes: Trek, Cannondale Tandem, Surly LHT

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by sngltrackdufus
A Brake cylinder hone will work fine if you stroke it right.It will leave a nice "cross hatch" pattern & hardly remove any tubing material.Just remember to keep the stones lubed.
I agree, and the seat post is clamped on the upper inch or so...
Old Hammer Boy is offline  
Old 02-10-06, 07:41 PM
  #15  
Banned.
 
sngltrackdufus's Avatar
 
Join Date: Sep 2005
Location: tartarus
Posts: 1,258

Bikes: MTB's & a Cyclocross

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Old Hammer Boy
I agree, and the seat post is clamped on the upper inch or so...
?
sngltrackdufus is offline  
Old 02-10-06, 08:30 PM
  #16  
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Posts: 8,108
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 937 Post(s)
Liked 652 Times in 367 Posts
Originally Posted by DocRay
whoa. really dumb idea. Danno, I wish you would stop making thes types of suggestions without knowing what you are talking about.

You want to remove only the corrosion, not ream out the tube, that will weaken the tube and make proper seatpost fit impossible, ruining the frame.

LIGHT abrasive to remove any rust, then you can try a light coat of clear laquer to seal, make sure it dries for days, then a new seatpost with lots of grease.
Right, reaming is a bad idea, but he suggested honing. That is a good idea.
Dan
Dan Burkhart is offline  
Old 02-11-06, 01:31 AM
  #17  
Senior Member
 
DannoXYZ's Avatar
 
Join Date: Jul 2005
Location: Saratoga, CA
Posts: 11,736
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 109 Post(s)
Liked 9 Times in 6 Posts
Originally Posted by DocRay
whoa. really dumb idea. Danno, I wish you would stop making thes types of suggestions without knowing what you are talking about.

You want to remove only the corrosion, not ream out the tube, that will weaken the tube and make proper seatpost fit impossible, ruining the frame.

LIGHT abrasive to remove any rust, then you can try a light coat of clear laquer to seal, make sure it dries for days, then a new seatpost with lots of grease.
So I take it you've never ever used the hone before and yet you pass judgement on my 10-years of using it a shop, eh? Blanket, all-or-nothing, black & white statements can't really compare to actual numbers. Here's what a brake-cylinder hone is used for:
  1. master-cylinders in cars have piston pushing inside a bore with 0.0010-0.0015" clearance.
  2. this gap is sealed with a rubber O-ring that's riding in a groove at the end of the piston
  3. brake-fluid is anhydrous and absorbs moisture from the air.
  4. over time, a year or two, the brake-fluid absorbs enough moisture that it actually starts to percipitate out of the fluid under cold-temperatures
  5. these droplets of water eventually corrodes and rusts the walls of the master-cylinder
  6. the corrosion and rust chews up the rubber O-ring and you end up with soft brakes, the pedal may even go all the way to the floor in extreme cases
  7. So... you repair the master-cylinder by disassembling and using the brake-cylinder hone on the corrosion and rust present in the cylinder.
  8. with WD40 or cutting-oil, 30-seconds with the hone typically removes 0.0002" of material (at minimal spring-tension setting). Usually a good idea to measure the cylinder and piston beforehand to ensure maximum-clearance of 0.0030" is not exceeded in the process of honing (reduce honing time if clearances are close to the limit already).
  9. replace O-ring on end of piston with new one,
  10. reassemble brake master-cylinder, pour in new fluid and you've got new brakes!
Note that the surface created by the hone is smooth enough to seal against 1300psi of hydraulic fluid with just a rubber O-ring!

With a seattube and cutting-oil, 10-20 seconds of the hone typically won't even remove the primer-paint that's sprayed down there! But it really does a nice job on the soft porous rust and other corrosion. It's much safer than reamers. You have to be careful with those and adjust them to the minimum since just 1/4-1/2 of a turn can take off 0.0020" of material instantly.

Next you're gonna tell me that programming the mill to take off 0.0005" from the surface of a corroded seat-post in my lathe is a dumb idea too right? After all you've probably done it a thousand times...


Last edited by DannoXYZ; 02-11-06 at 07:37 PM.
DannoXYZ is offline  
Old 02-11-06, 07:25 AM
  #18  
Senior Member
 
Join Date: Jul 2001
Posts: 1,396
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked 0 Times in 0 Posts
We use a doodad like this at our shop:

Moose is offline  
Old 02-11-06, 09:15 AM
  #19  
B.C. to D.C.
 
Join Date: Oct 2005
Location: between the Popeye's, the liquor store, the funeral home, and the strip club
Posts: 576

Bikes: 1992 Miyata Nine 14; 1971 Raleigh Super Course fixie conversion; 2006 Jamis Nova (853 version); 2001 Diamondback Topanga (SS conversion); 1956 Rudge Sports; 1971 Raleigh Competition (processing); 199? Schwinn World Sport (processing)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
where can one purchase a brake cylinder hone, how much does it cost, and do you need a drill press for it or what?
comradehoser is offline  
Old 02-11-06, 09:22 AM
  #20  
B.C. to D.C.
 
Join Date: Oct 2005
Location: between the Popeye's, the liquor store, the funeral home, and the strip club
Posts: 576

Bikes: 1992 Miyata Nine 14; 1971 Raleigh Super Course fixie conversion; 2006 Jamis Nova (853 version); 2001 Diamondback Topanga (SS conversion); 1956 Rudge Sports; 1971 Raleigh Competition (processing); 199? Schwinn World Sport (processing)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
never mind-- $10-15, attach to electric drill, available online & prob. auto parts stores.
comradehoser is offline  
Old 02-11-06, 04:52 PM
  #21  
Senior Member
 
Old Hammer Boy's Avatar
 
Join Date: Aug 2005
Location: Utah
Posts: 1,082

Bikes: Trek, Cannondale Tandem, Surly LHT

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by sngltrackdufus
?
To clarify....

The actual clamping surface on a seat tube, where it clamps the seat post is only a few centimeters long (an inch or even less). That's what secures the seat post from slipping or turning, unless the post is corroded tight further down the tube. My point is; if in the area below the clamp zone, the seat post is just a smidge oversized, the seat post clamp can still secure the post. Obviously, if it's way oversized, the post could shift some inside the tube, but a little clearance, like from a hone, shouldn't hurt. Follow?
Old Hammer Boy is offline  
Old 02-11-06, 07:14 PM
  #22  
Junior Member
 
Join Date: Jan 2006
Location: Lockhart, Texas
Posts: 82

Bikes: Navaro Buzz

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Take a dowel, put it in a drill, then wrap some steel wool on it and apply some light oil and spin away. Try to get a good size dowel and enough steel wool to be snug not tight this has worked for me on a couple of times on similar problems.
Mason Red is offline  
Old 02-11-06, 08:18 PM
  #23  
Banned.
 
sngltrackdufus's Avatar
 
Join Date: Sep 2005
Location: tartarus
Posts: 1,258

Bikes: MTB's & a Cyclocross

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Old Hammer Boy
To clarify....

The actual clamping surface on a seat tube, where it clamps the seat post is only a few centimeters long (an inch or even less). That's what secures the seat post from slipping or turning, unless the post is corroded tight further down the tube. My point is; if in the area below the clamp zone, the seat post is just a smidge oversized, the seat post clamp can still secure the post. Obviously, if it's way oversized, the post could shift some inside the tube, but a little clearance, like from a hone, shouldn't hurt. Follow?
Yes
sngltrackdufus is offline  
Old 02-11-06, 08:20 PM
  #24  
Banned.
 
sngltrackdufus's Avatar
 
Join Date: Sep 2005
Location: tartarus
Posts: 1,258

Bikes: MTB's & a Cyclocross

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Moose
We use a doodad like this at our shop:

WAIT!
That's a HONE!
sngltrackdufus is offline  
Old 02-11-06, 08:33 PM
  #25  
Banned.
 
sngltrackdufus's Avatar
 
Join Date: Sep 2005
Location: tartarus
Posts: 1,258

Bikes: MTB's & a Cyclocross

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by DannoXYZ
So I take it you've never ever used the hone before and yet you pass judgement on my 10-years of using it a shop, eh? Blanket, all-or-nothing, black & white statements can't really compare to actual numbers. Here's what a brake-cylinder hone is used for:
  1. master-cylinders in cars have piston pushing inside a bore with 0.0010-0.0015" clearance.
  2. this gap is sealed with a rubber O-ring that's riding in a groove at the end of the piston
  3. brake-fluid is anhydrous and absorbs moisture from the air.
  4. over time, a year or two, the brake-fluid absorbs enough moisture that it actually starts to percipitate out of the fluid under cold-temperatures
  5. these droplets of water eventually corrodes and rusts the walls of the master-cylinder
  6. the corrosion and rust chews up the rubber O-ring and you end up with soft brakes, the pedal may even go all the way to the floor in extreme cases
  7. So... you repair the master-cylinder by disassembling and using the brake-cylinder hone on the corrosion and rust present in the cylinder.
  8. with WD40 or cutting-oil, 30-seconds with the hone typically removes 0.0002" of material (at minimal spring-tension setting). Usually a good idea to measure the cylinder and piston beforehand to ensure maximum-clearance of 0.0030" is not exceeded in the process of honing (reduce honing time if clearances are close to the limit already).
  9. replace O-ring on end of piston with new one,
  10. reassemble brake master-cylinder, pour in new fluid and you've got new brakes!
Note that the surface created by the hone is smooth enough to seal against 1300psi of hydraulic fluid with just a rubber O-ring!

With a seattube and cutting-oil, 10-20 seconds of the hone typically won't even remove the primer-paint that's sprayed down there! But it really does a nice job on the soft porous rust and other corrosion. It's much safer than reamers. You have to be careful with those and adjust them to the minimum since just 1/4-1/2 of a turn can take off 0.0020" of material instantly.

Next you're gonna tell me that programming the mill to take off 0.0005" from the surface of a corroded seat-post in my lathe is a dumb idea too right? After all you've probably done it a thousand times...

OOOOOOO!!!
Look at all the pretty buttons to push & twist!
sngltrackdufus is offline  

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.