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

seatpost very tight fit

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 very tight fit

Old 03-03-17, 08:01 PM
  #1  
Senior Member
Thread Starter
 
Join Date: Dec 2016
Posts: 169
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 118 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
seatpost very tight fit

Hey so I found a seatpost and put it into a bike. But it was very hard to get it in.

The frane takes a 27.2 mm and im not sure what size the seatpost is. If it was to big would I be able to slide it in very stiff or would it just not go in at all.

Its so stiff I was only able to get it about 1/3 to 1/2 down.
Does this sound like ita the wrong size or just very stiff?
flik9999 is offline  
Old 03-03-17, 08:16 PM
  #2  
Calamari Marionette Ph.D
 
SquidPuppet's Avatar
 
Join Date: Dec 2013
Location: Coeur d' Alene
Posts: 7,862

Bikes: 3 Chinese Gas Pipe Nerdcycles and 2 Chicago Electroforged Boat Anchors

Mentioned: 75 Post(s)
Tagged: 0 Thread(s)
Quoted: 2358 Post(s)
Liked 33 Times in 26 Posts
All seat posts are "stiff". Some fit tightly and some fit loosely, but they are all "Stiff".

Did you grease it?
SquidPuppet is offline  
Old 03-03-17, 08:28 PM
  #3  
Senior Member
 
bargainguy's Avatar
 
Join Date: Sep 2012
Location: Trekland
Posts: 2,264
Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 510 Post(s)
Liked 275 Times in 177 Posts
Does the seatpost have any inscribed numbers that might be the diameter?

If not, best bet would be to take some calipers and measure both so you know both seatpost diameter and seat tube inner diameter.

If there's any gunk or corrosion on the inside of the seat tube, that can prevent the seatpost from being fully seated. A bike shop can use a seat tube reamer and clean it out for you.
bargainguy is offline  
Old 03-03-17, 08:37 PM
  #4  
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 30,225

Bikes: Catrike 559 I own some others but they don't get ridden very much.

Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1572 Post(s)
Liked 642 Times in 363 Posts
I'd check to see if either the seat post or the bike frame's seat tube were bent. I'd also check the inside of the seat tube for obstructions. If you can get it in 1/3 of the way I'd have to think that the seatpost was the right size.
__________________
My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
Retro Grouch is offline  
Old 03-03-17, 09:18 PM
  #5  
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 33,656

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

Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 2025 Post(s)
Likes: 0
Liked 1,091 Times in 737 Posts
Originally Posted by flik9999
The frane takes a 27.2 mm and im not sure what size the seatpost is. If it was to big would I be able to slide it in very stiff or would it just not go in at all.
Assuming the frame really does require a 27.2 mm seatpost, the next size up (27.4 mm) could probably be forced into it but it would be very tight.

As bargainguy noted, if the seat tube is rusty or dirty inside or distorted, the fit could be very tight even with the right size seat post.
HillRider is offline  
Old 03-03-17, 09:51 PM
  #6  
Senior Member
Thread Starter
 
Join Date: Dec 2016
Posts: 169
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 118 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
if it is the next size up 27.4 and its rammed in is that safe?
flik9999 is offline  
Old 03-03-17, 11:43 PM
  #7  
Full Member
 
peugeot mongrel's Avatar
 
Join Date: Jul 2010
Location: San Antonio, Texas
Posts: 475

Bikes: 84 Coppi - 94 Hujsak - 82 Colnago Superissimo - 78 Ciöcc - 70's Galmozzi - 73 Lambert - 78 Motobecane Grand Record - 87 Peugeot Triathlon - 66 Peugeot H-40 - 78 Peugeot U08 - 85 Raleigh C-40 - 82 miyata 310 - 82 Univega - 85 Sterling SIS Mixte

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 39 Post(s)
Liked 40 Times in 14 Posts
Originally Posted by flik9999
if it is the next size up 27.4 and its rammed in is that safe?
If you force a 27.4 in a 27.2 it will freeze up later and it will become one of those horror story's of a stuck seat post.
peugeot mongrel is offline  
Old 03-04-17, 02:49 AM
  #8  
Senior Member
 
Altimis's Avatar
 
Join Date: Jul 2016
Posts: 224
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 76 Post(s)
Liked 2 Times in 2 Posts
Originally Posted by peugeot mongrel
If you force a 27.4 in a 27.2 it will freeze up later and it will become one of those horror story's of a stuck seat post.
Its probably cracks first though if you actually forced it
Altimis is offline  
Old 03-04-17, 08:25 AM
  #9  
Senior Member
Thread Starter
 
Join Date: Dec 2016
Posts: 169
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 118 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Altimis
Its probably cracks first though if you actually forced it
I slid it applyed some weight but didnt use a hammer or anything
flik9999 is offline  
Old 03-04-17, 08:51 AM
  #10  
The Infractionator
 
AlexCyclistRoch's Avatar
 
Join Date: Mar 2016
Location: Rochester, NY
Posts: 2,202

Bikes: Classic road bikes: 1986 Cannondale, 1978 Trek

Mentioned: 9 Post(s)
Tagged: 1 Thread(s)
Quoted: 875 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
Could the post just be too long? My Cannondale seat tube narrows after a certain distance. I had to shorten a post so that my saddle could sit a bit lower.
AlexCyclistRoch is offline  
Old 03-04-17, 11:09 AM
  #11  
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 1,353 Times in 860 Posts
A perfect fit was attained in the process of taking my 27.0 RB1 seat tube , to 27.2, by having the seat post in hand,and using an adjustable reamer

to shave out just enough, ID until the post fit , and quitting..

a shop I worked in, used to get out a ball burnisher ( It looks like a grape cluster ), chucked up in a Drill-motor. and running it into the seat tube
of every new bike as we were assembling it. for a second. de burring the factory ream job.




...
fietsbob is offline  
Old 03-04-17, 03:18 PM
  #12  
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 17,909

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4128 Post(s)
Liked 3,700 Times in 2,219 Posts
Seat post fit is based on both the ID of the seat tube below the lug/joint area and the fit at the clamp. Note I didn't say "the ID at the clamp" The clamp insides are often not very round, distortion from heat being a common cause although other after manufacturing causes can also be present. The seat tube ID below the joint (and therefore away from any heat distortion) is usually the max post diameter that will work. Smaller post diameters might be needed to fit within the clamping portion. I suggest a lot of care and consideration before taking a reamer to a seat tube, once metal comes off it usually is gone forever and where that metal is removed is not always where it seems that it should be from. I have heard of seat tube wall being tragically thinned to a point of failure. The tool operator was watching the post fit in the clamped portion and not what was going on below. Honing with the common flex hones won't remove hardly any metal but will reduce down any burrs. I would work a tight clamp area first with mechanical methods then metal removing ones. Andy
Andrew R Stewart is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
shuru421
Classic & Vintage
15
10-30-16 08:57 PM
Andy_K
Classic & Vintage
21
03-29-16 12:59 PM
kflagg
Classic & Vintage
13
06-19-14 04:16 AM
Grambo
Bicycle Mechanics
1
01-01-13 02:58 PM
Robuchon
Clydesdales/Athenas (200+ lb / 91+ kg)
10
08-11-11 06:46 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
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.