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

Seatpost Fitting

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.

Seatpost Fitting

Old 10-18-13, 12:43 AM
  #1  
Senior Member
Thread Starter
 
Join Date: Jun 2012
Posts: 153
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Liked 0 Times in 0 Posts
Seatpost Fitting

I currently have a 26.6 seatpost on my road bike. I was wondering if using a 26.2 seatpost in the future will cause any problems in fitting? Will it be too small to fit in my frame leading to overtightening the lug in the back?
PapaGanoosh is offline  
Old 10-18-13, 01:11 AM
  #2  
Senior Member
 
Join Date: Jan 2012
Location: Spokane, WA
Posts: 2,255

Bikes: Specialized Sequoia Elite/Motobecane Fantom Cross Team Ti/'85 Trek 520

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
If a 26.6 seatpost fits perfectly now with no play in it at all, then you need a 26.6 period. You should not play around with other size seat posts since all that will do is slowly weaken the seatpost and deform the seat post tightening ears. Your post should fit snugly with NO play.

A 26.2 post will be WAYYYY too small. You might barely get away with possibly using a 26.5 post but not sure if they even make such a thing.
bobotech is offline  
Old 10-18-13, 01:26 AM
  #3  
Senior Member
 
Join Date: Mar 2008
Posts: 8,688
Mentioned: 46 Post(s)
Tagged: 0 Thread(s)
Quoted: 1074 Post(s)
Liked 295 Times in 222 Posts
Originally Posted by PapaGanoosh
I currently have a 26.6 seatpost on my road bike. I was wondering if using a 26.2 seatpost in the future will cause any problems in fitting?
Assuming the current one is a good fit - yes.

Originally Posted by PapaGanoosh
Will it be too small to fit in my frame ?
Assuming the current one is a good fit - yes.

Originally Posted by PapaGanoosh
...leading to overtightening the lug in the back?
Assuming the current one is a good fit - quite probably.

But you can always shim the 26.2 to something a lot closer to 26.6.
dabac is offline  
Old 10-18-13, 04:45 AM
  #4  
Senior Member
 
Murray Missile's Avatar
 
Join Date: Jun 2013
Location: 700 Ft. above sea level.
Posts: 3,189

Bikes: More than there were awhile ago.

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 611 Post(s)
Liked 1,184 Times in 567 Posts
I've been using a bronze seat post shim that is 3" long in my MTB since 1997. I'm tall and have a lot of seat post showing and for a period of several years I tipped the scales just a few ounces under 250 Lbs. I have experienced no issues using a shim.
Murray Missile is offline  
Old 10-18-13, 08:26 AM
  #5  
Senior Member
 
surreal's Avatar
 
Join Date: Mar 2002
Location: NJ
Posts: 3,084
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 5 Times in 4 Posts
These threads drive me absolutely batty. Seatposts are available in basically every size ever used, and 99% of them can be had for dirt cheap.... Why not get the right size? It sounds to me like you already have the right size (if, in fact, 26.6 is the correct size for your frame)-- why not just keep that one in service?

If the current post is broken, why not just buy a danged 26.6mm post? I have like, three 26.6 mm posts in my basement, plus a few in some bikes. Common used 26.6 posts from the 80s are free or basically free when you find them. Brand new pipe-n-guts style seatposts are less than $5 (and an extra $2.50 for the guts). You might be tempted to save a few bucks by just using what's on hand, but consider this: a seatpost is a lot cheaper than a frame. Off-sized posts have killed a lot of frames over the years.
surreal is offline  
Old 10-18-13, 09:21 AM
  #6  
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,598

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,354 Times in 861 Posts
More common sizes are 25.4 , or 1 inch, then you will find shims for all sorts of frame ID's
precision machined.. Wheels Mfg and QBP-PS both make seatpost sizing shims

less common 25.0, mm.. I have bought USE shims from the UK [through LBS]
they, the USE company, make seatposts just in 25 then in 27.2 , then again in larger than that
rather than all diameters in 0.2mm steps.

Kalloy makes seat posts like that they are very economical, and commonly available.

I bought a Thudbuster suspension seat post in 27.2, and a shim 27.2>31.4

to use in my frame with a 31.4 mm ID seat tube..

undersized seatposts, if used, damage frames , maybe irreversibly.

Last edited by fietsbob; 10-18-13 at 09:25 AM.
fietsbob is offline  
Old 10-18-13, 09:58 AM
  #7  
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,504

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 139 Post(s)
Tagged: 1 Thread(s)
Quoted: 5681 Post(s)
Liked 2,386 Times in 1,320 Posts
Originally Posted by PapaGanoosh
I currently have a 26.6 seatpost on my road bike. I was wondering if using a 26.2 seatpost in the future will cause any problems in fitting? Will it be too small to fit in my frame leading to overtightening the lug in the back?
Question.

If the 26.6 post fits and works, why would you even consider another? It's like saying I've worn size 9 shoes all my life, but I'm thinking of trying some size 7.

Post fit is very critical, and has to be a running fit inside the tube. Otherwise, even if you can clamp it at the top, it's rock and move around below, creaking and putting undue stress on the seat tube just below the clamp
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

Just because I'm tired of arguing, doesn't mean you're right.

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is online now  
Old 10-18-13, 11:01 AM
  #8  
Senior Member
Thread Starter
 
Join Date: Jun 2012
Posts: 153
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Liked 0 Times in 0 Posts
Originally Posted by FBinNY
Question.


If the 26.6 post fits and works, why would you even consider another? It's like saying I've worn size 9 shoes all my life, but I'm thinking of trying some size 7.


Post fit is very critical, and has to be a running fit inside the tube. Otherwise, even if you can clamp it at the top, it's rock and move around below, creaking and putting undue stress on the seat tube just below the clamp

I wanted to install a fluted seat post and had a 26.2 lying around. Was wondering if I should get another one.
PapaGanoosh is offline  
Old 10-18-13, 11:08 AM
  #9  
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,598

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,354 Times in 861 Posts
Math: 26.6mm - 26.2mm = 0.4mm '/, 2 = 0.2mm, you need an 0.2mm thick shim to make up the difference..

what makes the fluted seat post so special ?

its a look that has been done in cheap as well as expensive seatposts ..
fietsbob is offline  
Old 10-18-13, 12:22 PM
  #10  
Senior Member
 
Join Date: Jul 2006
Location: Middle of the road, NJ
Posts: 3,137
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 292 Post(s)
Liked 106 Times in 69 Posts
I had a person that came in to my shop last night asking fo a seat pole. You mean a seat post? "Yeah, seat pole." What size? "A long one." No, no, a seat post, what diameter, how thick? "Yeah, a long one, for a crusier. A pole." show him the parts binwith seat poles, eh posts. He grabes a long one, "Yeah, that's for a cruiser, How much?" 2 bucks. Pays and leaves happy.

I know it doen't help the op, but since we are talking about poles...
leob1 is offline  
Old 10-18-13, 04:36 PM
  #11  
Senior Member
 
surreal's Avatar
 
Join Date: Mar 2002
Location: NJ
Posts: 3,084
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 5 Times in 4 Posts
Many "crusier poles" are going to be 13/16", 7/8", or 1".... so, maybe he got lucky?
surreal is offline  
Old 10-18-13, 09:29 PM
  #12  
Senior Member
 
Join Date: Jan 2012
Location: Spokane, WA
Posts: 2,255

Bikes: Specialized Sequoia Elite/Motobecane Fantom Cross Team Ti/'85 Trek 520

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Originally Posted by leob1
I had a person that came in to my shop last night asking fo a seat pole. You mean a seat post? "Yeah, seat pole." What size? "A long one." No, no, a seat post, what diameter, how thick? "Yeah, a long one, for a crusier. A pole." show him the parts binwith seat poles, eh posts. He grabes a long one, "Yeah, that's for a cruiser, How much?" 2 bucks. Pays and leaves happy.

I know it doen't help the op, but since we are talking about poles...
Ugh, I HATE ignorant customers like that. Its one thing if the customer is ignorant but willing to learn how to fix the bike or learn the proper terms but people like your customer drive me nuts with their thickheadedness.
bobotech is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
shuru421
Classic & Vintage
30
01-22-19 08:17 PM
wunderkind
Bicycle Mechanics
17
11-17-15 11:30 AM
byrd48
Bicycle Mechanics
22
07-06-13 03:37 PM
Suttree
Classic & Vintage
4
09-27-11 03:07 PM
ryaneezy
Singlespeed & Fixed Gear
8
05-05-11 05:11 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
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.