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

Can I shim a seatpost/seat 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.

Can I shim a seatpost/seat tube?

Old 07-22-22, 06:36 AM
  #26  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 5,639

Bikes: 1989 Cinelli Supercorsa

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 3429 Post(s)
Liked 2,817 Times in 1,717 Posts
Originally Posted by sovende
Using a shim to get a proper fit between a seat tube and seat post isn’t nearly as “cheap” or blasphemous as some might like to think.
Yes, it is. On anything other than a kid's bike. It's a shortcut, pure and simple.
smd4 is online now  
Old 07-22-22, 03:07 PM
  #27  
sovende
Senior Member
 
Join Date: Jul 2017
Location: Western WI (USA)
Posts: 555

Bikes: TNTL (Too numerous to list)

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 184 Post(s)
Liked 147 Times in 115 Posts
Originally Posted by smd4
Yes, it is. On anything other than a kid's bike. It's a shortcut, pure and simple.
On a new, relatively expensive bike, I’d tend to agree but for someone rehabbing a classic / vintage bike that has suffered some level of abuse, misuse or disuse and needs a replacement seat post to bring it back to its former glory, using a shim would, IMHO & perhaps that of others, be completely acceptable. Restoration to museum quality would be an exception.
sovende is offline  
Old 07-31-22, 09:02 PM
  #28  
Fredo76
The Wheezing Geezer
 
Fredo76's Avatar
 
Join Date: Oct 2021
Location: Española, NM
Posts: 995

Bikes: 1976 Fredo Speciale, Jamis Citizen 1, Ellis-Briggs FAVORI, Rivendell Clem Smith Jr.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 393 Post(s)
Liked 856 Times in 422 Posts
Originally Posted by smd4
Yes, it is. On anything other than a kid's bike. It's a shortcut, pure and simple.
Author and philosopher Robert M. Pirsig wrote an entire book, basically about why you are wrong! I am not making this up (although I am exaggerating a bit).

Although Zen and the Art of Motorcycle Maintenance was a popular novel, it was also assigned reading in my engineering class. It has a lengthy scene about a shim. You should read it.
Fredo76 is offline  
Old 07-31-22, 09:07 PM
  #29  
smd4
Senior Member
 
Join Date: Dec 2020
Location: Wake Forest, NC
Posts: 5,639

Bikes: 1989 Cinelli Supercorsa

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 3429 Post(s)
Liked 2,817 Times in 1,717 Posts
Originally Posted by Fredo76
Author and philosopher Robert M. Pirsig wrote an entire book, basically about why you are wrong! I am not making this up (although I am exaggerating a bit).

Although Zen and the Art of Motorcycle Maintenance was a popular novel, it was also assigned reading in my engineering class. It has a lengthy scene about a shim. You should read it.
Shims are shortcuts. Nothing wrong with them, but shortcuts nonetheless.
smd4 is online now  
Old 07-31-22, 09:32 PM
  #30  
zandoval 
Senior Member
 
zandoval's Avatar
 
Join Date: May 2010
Location: Bastrop Texas
Posts: 4,416

Bikes: Univega, Peu P6, Peu PR-10, Ted Williams, Peu UO-8, Peu UO-18 Mixte, Peu Dolomites

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 928 Post(s)
Liked 1,595 Times in 1,021 Posts
To make up for a 0.2mm difference in a seat post size I did a temporary fix of using a shim made of Beer Can aluminum about 6"/15cm long 3/4"/2cm wide. Never did get another seat post and the shim is still doing just fine after 10 years...

Originally Posted by smd4
You guys are the cheapest people I know. Shims? Really?? Pry open your wallets and buy the correct size seatpost. Sell the wrong one on eBay. Sheesh.
Of course you are right and I agree... But then I would have to turn in my "Cheap Bastard" membership card... Ha
__________________
No matter where you're at... There you are... Δf:=f(1/2)-f(-1/2)

Last edited by zandoval; 07-31-22 at 09:36 PM.
zandoval is online now  
Old 07-31-22, 10:14 PM
  #31  
DiabloScott
It's MY mountain
 
DiabloScott's Avatar
 
Join Date: Sep 2006
Location: Mt.Diablo
Posts: 9,991

Bikes: Klein, Merckx, Trek

Mentioned: 70 Post(s)
Tagged: 0 Thread(s)
Quoted: 4311 Post(s)
Liked 2,954 Times in 1,601 Posts
Originally Posted by smd4
Yes, it is. On anything other than a kid's bike. It's a shortcut, pure and simple.
Maybe a beercan shim, but they sell shims especially designed and machined for this purpose and it is an accommodation more than a shortcut. You likely wouldn't even notice.
DiabloScott is offline  
Old 07-31-22, 11:17 PM
  #32  
Polaris OBark
ignominious poltroon
 
Polaris OBark's Avatar
 
Join Date: Jan 2022
Posts: 3,925
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 2184 Post(s)
Liked 3,336 Times in 1,741 Posts
I was reading the fine print that came with my Problem Solvers 0.7mm shim. It says you should not use it with a carbon seat post, or a carbon frame. (I don't think this is specific to any particular diameter shim or thickness of shim that they make. I think it is a general directive. It does make sense because a shim focuses a force on a smaller area).
Polaris OBark is offline  
Old 07-31-22, 11:19 PM
  #33  
Polaris OBark
ignominious poltroon
 
Polaris OBark's Avatar
 
Join Date: Jan 2022
Posts: 3,925
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 2184 Post(s)
Liked 3,336 Times in 1,741 Posts
Originally Posted by smd4
Shims are shortcuts. Nothing wrong with them, but shortcuts nonetheless.
Unfortunately, it is worse than you are saying (see above).

Reluctantly, I will be taking your advice.
Polaris OBark is offline  
Likes For Polaris OBark:
Old 08-01-22, 04:36 AM
  #34  
Fredo76
The Wheezing Geezer
 
Fredo76's Avatar
 
Join Date: Oct 2021
Location: Española, NM
Posts: 995

Bikes: 1976 Fredo Speciale, Jamis Citizen 1, Ellis-Briggs FAVORI, Rivendell Clem Smith Jr.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 393 Post(s)
Liked 856 Times in 422 Posts
Didn't even enter my mind. Another reason not to buy a carbon-fibre frame! You might need to use a shim! Or a bike stand...
Fredo76 is offline  
Old 08-01-22, 05:36 AM
  #35  
Polaris OBark
ignominious poltroon
 
Polaris OBark's Avatar
 
Join Date: Jan 2022
Posts: 3,925
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 2184 Post(s)
Liked 3,336 Times in 1,741 Posts
Originally Posted by Fredo76
Didn't even enter my mind. Another reason not to buy a carbon-fibre frame! You might need to use a shim! Or a bike stand...
Ti frame. Carbon post.
Polaris OBark is offline  
Likes For Polaris OBark:
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
flik9999
Bicycle Mechanics
11
03-04-17 03:18 PM
shuru421
Classic & Vintage
15
10-30-16 08:57 PM
Andy_K
Classic & Vintage
21
03-29-16 12:59 PM
f33dback
Bicycle Mechanics
5
06-01-13 10:17 AM
Grambo
Bicycle Mechanics
1
01-01-13 02:58 PM

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 -

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