General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

SeatPOST sizes?

Old 08-31-18, 09:06 PM
  #1  
2pedals5
Senior Member
Thread Starter
 
Join Date: Jul 2018
Posts: 89
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
SeatPOST sizes?

How many sizes are there for seatpost? I askee this because I came to anbidea of switching one seat saddle to another bike but when I do, one seatpost couldnt fix on other bike seat hole. How do I know what size do I have?
2pedals5 is offline  
Old 08-31-18, 09:14 PM
  #2  
DrIsotope
Non omnino gravis
 
DrIsotope's Avatar
 
Join Date: Feb 2015
Location: SoCal, USA!
Posts: 6,989

Bikes: Nekobasu, Pandicorn

Mentioned: 104 Post(s)
Tagged: 0 Thread(s)
Quoted: 3785 Post(s)
Liked 299 Times in 207 Posts
Well, the Thomson Elite comes in:

25.0mm
25.4mm
26.0mm
26.6mm
26.8mm
27.0mm
27.2mm
27.4mm
28.6mm
29.4mm
29.8mm
30.0mm
30.6mm
30.8mm
30.9mm
31.4mm
31.6mm
32.4mm

As to yours, the diameter and length is often stamped near the bottom of the post, on the part that resides inside the frame.
__________________
DrIsotope is offline  
Old 08-31-18, 09:14 PM
  #3  
HTupolev
Senior Member
 
Join Date: Apr 2015
Location: Seattle
Posts: 2,797
Mentioned: 34 Post(s)
Tagged: 0 Thread(s)
Quoted: 1232 Post(s)
Liked 55 Times in 38 Posts
Originally Posted by 2pedals5 View Post
How many sizes are there for seatpost?
About thirty trillion.

Most modern bikes probably use seatposts with a diameter of 27.2mm, 30.9mm, or 31.6mm.

How do I know what size do I have?
Very carefully measure it with calipers.
Sometimes the diameter is written somewhere on the seatpost.

Always use a precisely-fitting seatpost.
HTupolev is offline  
Old 08-31-18, 09:14 PM
  #4  
thumpism 
Bikes are okay, I guess.
 
thumpism's Avatar
 
Join Date: Jan 2015
Location: Richmond, Virginia
Posts: 4,641

Bikes: Waterford Paramount Touring, Bridgestone RB-T, Trek 510 city build, Giant CFM-2, Raleigh Sports 3-speeds in M23 & L23, Schwinn Cimarron oddball build

Mentioned: 36 Post(s)
Tagged: 0 Thread(s)
Quoted: 1236 Post(s)
Liked 29 Times in 21 Posts
Dozens, from about 24.0mm to more than 31.8mm, and that was just while I was in the business more than 15 years ago. Buy a good caliper and learn to use it.
thumpism is offline  
Old 08-31-18, 09:17 PM
  #5  
2pedals5
Senior Member
Thread Starter
 
Join Date: Jul 2018
Posts: 89
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thank you guys! Very helpful!!
2pedals5 is offline  
Old 09-01-18, 05:40 AM
  #6  
bluehills3149
Senior Member
 
bluehills3149's Avatar
 
Join Date: Jun 2014
Location: Brooklyn USA
Posts: 229

Bikes: depends what week it is..

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
And if you can't measure or see the size stamped, Sheldon Brown has a pretty good database of many bikes and their sizes here:
https://www.sheldonbrown.com/seatpost-sizes.html
bluehills3149 is offline  
Old 09-01-18, 08:56 AM
  #7  
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 41,396

Bikes: 8

Mentioned: 188 Post(s)
Tagged: 0 Thread(s)
Quoted: 6878 Post(s)
Liked 229 Times in 187 Posts
25.0mm
25.4mm
26.0mm
26.6mm
26.8mm
27.0mm
27.2mm
Kalloy , Much lower cost, stops, at 27.2..
in addition , a commonly available [Bike shop order] seat post sizing shim sleeve has ID of 25.4 (1") or 27.2mm, and made in all the previously listed OD.. * more likely in 1" ID being only 0.2mm larger than 27.2

27.4mm *
28.6mm
29.4mm
29.8mm
30.0mm
30.6mm
30.8mm
30.9mm
31.4mm
31.6mm
32.4mm





...

Last edited by fietsbob; 09-01-18 at 09:07 AM.
fietsbob is offline  
Old 09-01-18, 09:05 AM
  #8  
dedhed
SE Wis
 
dedhed's Avatar
 
Join Date: Apr 2005
Location: Milwaukee, WI
Posts: 5,115

Bikes: '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 696 Post(s)
Liked 67 Times in 56 Posts
If you plan on working on bikes buy at least a cheap calipers.

https://www.harborfreight.com/hand-t...per-63586.html
dedhed is online now  
Old 09-01-18, 09:13 AM
  #9  
dedhed
SE Wis
 
dedhed's Avatar
 
Join Date: Apr 2005
Location: Milwaukee, WI
Posts: 5,115

Bikes: '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 696 Post(s)
Liked 67 Times in 56 Posts
They start at 7/8"(22.2mm) and go up into the low 30's.
Then there is the whole proprietary aero designs. Even measuring your existing doesn't guarantee that someone didn't stuff the wrong size one in unless you know for sure it's original.
dedhed is online now  
Old 09-01-18, 09:15 AM
  #10  
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 41,396

Bikes: 8

Mentioned: 188 Post(s)
Tagged: 0 Thread(s)
Quoted: 6878 Post(s)
Liked 229 Times in 187 Posts
Originally Posted by 2pedals5 View Post
How many sizes are there for seatpost? I askee this because I came to anbidea of switching one seat saddle to another bike but when I do, one seatpost couldnt fix on other bike seat hole. How do I know what size do I have?
as indicated , Measure..

[math ; wrap a piece of paper around the seat post, mark it,
where it comes around to meet itself,
that is the circumference, of the post ,
Then, you can use a ruler to measure the length between marks.]

from there you can calculate the diameter..

.....

reaming at bike factories can have variation , as reamer wears,
over a production run,
and users bend the ears on the frame to compensate..

I have used a adjustable, hand , reamer , and gone up 1,
0.2mm diameter size post. to get a precise fit..

Was 27.0, to 27.2mm , had the post in hand and stopped cutting
as soon as it fit..




...

Last edited by fietsbob; 09-01-18 at 09:27 AM.
fietsbob is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Couch
Foo
1
12-25-10 05:21 PM
timmyquest
Great Lakes
16
02-17-09 05:27 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

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.