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

Old Peugeot Seat Post replacement

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.

Old Peugeot Seat Post replacement

Old 04-21-12, 07:40 AM
Thread Starter
Join Date: Feb 2012
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Old Peugeot Seat Post replacement

I just bought a pretty awesome looking Peugeot Tourmalet of unknown age (ebay seller thought 70s, but the decals look 80s and someone more knowledgeable than me said the kind of lugging wasn't done until the late 80s). Everything looks in good working order - except the seat post is super scratched and I can't get it down far enough to fit me. I did a rough measurement and believe it to be 25.00 mm (although it could be 25.4 mm). I have a few questions about replacement:

a) Do I have to find a vintage seat post or will new ones be compatible?
b) Does size matter? They come in different lengths. How do I know if something will be too long or too short?
c) I'm on a budget and the cheapest ones seem to be aluminium. Does that matter given my bike is steel? This is just a city commuter bike that won't get more than 30 or so miles a week so comfort isn't my biggest concern.
d) Is there any surefire way to know seat post size? Like is it printed somewhere or is my ruler the best I can do?
e) Are there any other parts I need in addition to seat post to make this happen?

shibbie is offline  
Old 04-21-12, 07:50 AM
Senior Member
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 32,803

Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!

Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 1649 Post(s)
Likes: 0
Liked 503 Times in 380 Posts
a. A new seatpost will be fine
b. Length doesn't matter as long as you have enough to have the "minimum insertion" mark below the seattube's top. Too long could hit the water bottle braze-ons inside the seat tube but that can be corrected with a hacksaw.
c. Aluminum is by far the best material for a seatpost. They come in both cheap and expensive models and can be used in a frame of any material. Be sure to grease it to prevent corrosion and binding.
d. A bike dealer should have a gauge that will give you the correct seatpost diameter for your frame. Seatposts themselves usually have their diameter engraved on them below the minimum insertion line.
e. Do you have the clamp bolt for the frame?
HillRider is offline  
Old 04-21-12, 08:13 AM
Thread Starter
Join Date: Feb 2012
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks for the info, Hillrider. I do have everything that was originally there.
shibbie is offline  
Old 04-21-12, 08:37 AM
Senior Member
zukahn1's Avatar
Join Date: Oct 2011
Location: Fairplay Co
Posts: 8,175

Bikes: Current 79 Nishiki Custum Sport, Jeunet 620, notable previous bikes P.K. Ripper loop tail, Kawahara Laser Lite, Paramount Track full chrome, Raliegh Internatioanl, Motobecan Super Mirage. 59 Crown royak 3 speed

Mentioned: 21 Post(s)
Tagged: 1 Thread(s)
Quoted: 482 Post(s)
Liked 286 Times in 177 Posts
If your not sure on the size of seat post you should probably take it to a shop and have the size checked. A lot of Peugoets took none standard size or type posts.
zukahn1 is offline  
Old 04-21-12, 08:42 AM
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 1,316 Times in 827 Posts
Given 25,4 is an inch , and one thing the French have favored is the Metric system,
with it's Napoleonic Origins.. so Id vote even 25mm.
Kalloy makes decent seat posts starting at 25,0., some 23mm..

Wait till you seek out stems and find out their penchant for being the metric outlier .
22.0 stems are quite uncommon, as replacements, these days
fietsbob is offline  
Old 04-21-12, 09:03 AM
Senior Member
jyl's Avatar
Join Date: Aug 2006
Location: Portland OR
Posts: 7,642

Bikes: 61 Bianchi Specialissima 71 Peugeot G50 7? P'geot PX10 74 Raleigh GranSport 75 P'geot UO8 78? Raleigh Team Pro 82 P'geot PSV 86 P'geot PX 91 Bridgestone MB0 92 B'stone XO1 97 Rans VRex 92 Cannondale R1000 94 B'stone MB5 97 Vitus 997

Mentioned: 140 Post(s)
Tagged: 0 Thread(s)
Quoted: 389 Post(s)
Likes: 0
Liked 42 Times in 27 Posts
That seat post would likely be aluminum, which is the best material.

You should be able to remove most of the scratches and restore the post to gleaming condition, with a couple hours' work. Search here about polishing.

Can't get the post down far enough - hmm, is the bike too big for you then? How low are you trying to get the seatpost - measured by inches of post you want to leave exposed above the top of the seat tube?

Anyway, pull the seatpost out, sand/polish it smooth and shiny as above, grease it (liberally!), and try re-inserting it. It should go all the way in. You can cut off the end if absolutely necessary, but that should not be necessary and is to be avoided if possible.

Peugeots used 24.0 mm, 25.0 mm and I've seen 22.0 mm and heard of other oddball sizes. Have it accurately measured. A fair number of options at 25.0 mm, much fewer at 24.0 mm.
jyl is offline  
Old 04-21-12, 12:44 PM
Subjectively Insane
MilitantPotato's Avatar
Join Date: Jul 2008
Location: Saint Louis, Missouri
Posts: 802

Bikes: '09 Rodriguez Adventurer Custom, '08 Trek 7.3Fx

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
It'd be a good idea to have the seat tube scrubbed of rust. I'm having a brain fart on the name of the bit, but it's more or less steel wool on a rod. That may let ya get the seat post further into the frame.

If you're hacksawing the post shorter as jyl mentioned, be sure the post goes an inch or two below the seat-stay and top tube junction.

Also as jyl said, accurate sizing is important. Having a post .2mm too small is a lot.

Last edited by MilitantPotato; 04-21-12 at 12:51 PM.
MilitantPotato is offline  
Related Topics
Thread Starter
Last Post
Classic & Vintage
10-23-18 08:04 AM
Bicycle Mechanics
10-23-17 11:39 AM
Classic & Vintage
01-27-16 11:38 AM
Bicycle Mechanics
03-30-13 01:40 PM
Bicycle Mechanics
05-13-10 04:38 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 - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.