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

Seatpost size: 27.0 or 27.2 mm

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 size: 27.0 or 27.2 mm

Old 12-01-22, 01:40 AM
  #26  
maddog34
Senior Member
 
maddog34's Avatar
 
Join Date: Jul 2015
Location: NW Oregon
Posts: 2,075

Bikes: !982 Trek 930R Custom, Diamondback ascent with SERIOUS updates, Fuji Team Pro CF and a '09 Comencal Meta 5.5

Mentioned: 13 Post(s)
Tagged: 1 Thread(s)
Quoted: 896 Post(s)
Liked 271 Times in 211 Posts
Originally Posted by ser_gio

This is the catalogue page of the bike. I have enjoyed riding this.
Cool Lookin' Bike, Dude! it's a step up from the Bianchi MTB's of that age i've seen... Well worth Restoring.... REMEMBER.. As you clean up the Frame tube, the DEBRIS will fall Into The Bottom Bracket area... my advice is to Remove the Crank and Bottom Bracket! If you can't do this, then Lay the Bike On It's SIDE as you clean the rust out of the seat tube, then Empty the Seat tube frequently... and Do Not sand too much out,or your new seat post will slide right down in and be a pain to set correctly.. you can make a flapper sanding tool with a piece of 1/4" or 5/16" steel rod and a Hack saw with a fine tooth blade, 24 tpi or 32 tpi... and some 2" 120 grit Emery cloth strip from a hardware store. you'll need a hand drill too, but WAY easier. Just remove the outty rust, no need to polish every pit out of the inner surface... test frequently, dump debris frequently.

Last edited by maddog34; 12-01-22 at 01:51 AM.
maddog34 is offline  
Likes For maddog34:
Old 12-01-22, 01:46 AM
  #27  
maddog34
Senior Member
 
maddog34's Avatar
 
Join Date: Jul 2015
Location: NW Oregon
Posts: 2,075

Bikes: !982 Trek 930R Custom, Diamondback ascent with SERIOUS updates, Fuji Team Pro CF and a '09 Comencal Meta 5.5

Mentioned: 13 Post(s)
Tagged: 1 Thread(s)
Quoted: 896 Post(s)
Liked 271 Times in 211 Posts
Originally Posted by Andrew R Stewart
BioPace, U brakes, "X" frame design... a classic example of the early 1990s attempts to better the MtB experience. At least Bianchi saw the reason to not install the rear U brake on the chainstay

Interesting that the catalog shows an Al post and the OP's bike has a steel one... Andy
like i mentioned earlier... seats AND posts get swapped as a unit fairly often... those 6 piece steel rail clamps baffle most folks. Seat gets a hole or cracks from age, Swap the entire thing from a lesser bike... Real common.

and good point about those mud catcher Brakes...;-)

Last edited by maddog34; 12-01-22 at 02:02 AM.
maddog34 is offline  
Likes For maddog34:
Old 12-01-22, 08:10 AM
  #28  
JohnDThompson 
Old fart
 
JohnDThompson's Avatar
 
Join Date: Nov 2004
Location: Appleton WI
Posts: 24,347

Bikes: Several, mostly not name brands.

Mentioned: 149 Post(s)
Tagged: 0 Thread(s)
Quoted: 3307 Post(s)
Liked 2,786 Times in 1,608 Posts
Originally Posted by Andrew R Stewart
BioPace, U brakes, "X" frame design... a classic example of the early 1990s attempts to better the MtB experience.
There's nothing new under the sunů

https://onlinebicyclemuseum.co.uk/1935-raleigh-x-frame/
JohnDThompson is offline  
Likes For JohnDThompson:
Old 12-01-22, 09:34 AM
  #29  
ser_gio
Newbie
Thread Starter
 
ser_gio's Avatar
 
Join Date: Nov 2022
Location: Toledo, OH
Posts: 19
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Liked 3 Times in 3 Posts
Originally Posted by FBinNY
More proof that a picture is worth a thousand words. Both the problem and solution are now obvious.

The problem is the rust, and the post will fit perfectly with a light sanding to remove it. Or replace it with an aluminum 27.2 post.

BTW - be careful and do not overnighter the clamp. The ears seem to be bent inward, probably from overtightening in the past. Keep it up and you might Crack the tube, or bend them in enough to touch.
Thank you for the advice. Regarding overtightening, you have the eyes and experience to note right away! You are correct. I was at the age of 15 when this bike was bought. I did not have much knowledge back then. So, overtightening happened at that time. But still, I should take some credit that I am the only one among my peers who still have a bike from that age and which is still good looking I no longer overtighten.
ser_gio is offline  
Old 12-01-22, 09:49 AM
  #30  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 17,324

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: 3883 Post(s)
Liked 3,102 Times in 1,896 Posts
John, like me, looks to be a sort of historian of design. I had the great opportunity to work for a shop that collected turn of the century (the1899/1900 turn, they considered WW1 as their cut off for collecting) bikes. Each winter we would service one or two of the collection and I got to have hands on experience with bikes that were 75ish years old. This just as the Asian invasion began and through the 1984 Olympic build up. The claims many made as they brought out new products were interesting as I had that 75 year old example of the "NEW and BETTER" product, but done in wood and hide instead of metal, plastic and vinyl. I thought it was pretty common knowledge that Shimano had a department that only did patent searching for both the base designs and their expiration dates, than "borrow" the expired designs.

An interesting part of Bianchi's claim is the separation of the pedaling stiffness need and the bump compliance and how a frame handles them. It seems to my lay eyes that going from a main frame that is a 4 sided structure (common "diamond" frame) to a design that has only triangles as the structural shapes would result in greater stiffness. Not exactly the changes that I would think adds compliance or absorbs road shock. But I'm sure that this claim was written by the marketing dept (or by extension, the magazine writer) and not by an engineer.

I do agree with the comments about the poorly done seat post binder. I've seen many of this type of welded on ears become bent inwards on many bikes. That, as a MtB, the binder could/would be loosened/tightened often this poor binder design is particularly sad. I suspect this bike is one of the Asian made Bianchis and that Bianchi didn't have a lot of design detail involvement beyond the "X" main frame aspect. But this is one more example why Bianchi is a bit player in the North American market, both back then and now. Andy
__________________
AndrewRStewart
Andrew R Stewart is offline  
Old 12-01-22, 11:31 AM
  #31  
ser_gio
Newbie
Thread Starter
 
ser_gio's Avatar
 
Join Date: Nov 2022
Location: Toledo, OH
Posts: 19
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Liked 3 Times in 3 Posts
Originally Posted by maddog34
Cool Lookin' Bike, Dude! it's a step up from the Bianchi MTB's of that age i've seen... Well worth Restoring.... REMEMBER.. As you clean up the Frame tube, the DEBRIS will fall Into The Bottom Bracket area... my advice is to Remove the Crank and Bottom Bracket! If you can't do this, then Lay the Bike On It's SIDE as you clean the rust out of the seat tube, then Empty the Seat tube frequently... and Do Not sand too much out,or your new seat post will slide right down in and be a pain to set correctly.. you can make a flapper sanding tool with a piece of 1/4" or 5/16" steel rod and a Hack saw with a fine tooth blade, 24 tpi or 32 tpi... and some 2" 120 grit Emery cloth strip from a hardware store. you'll need a hand drill too, but WAY easier. Just remove the outty rust, no need to polish every pit out of the inner surface... test frequently, dump debris frequently.
Thank you for your advice. I am a new member and glad to join such experienced and generous (to share knowledge) group of people. My restoration plan is to dismantle all parts, including the bottom bracket, clean, sand, prime, touch-up the frame, clean and reinstall all parts. I don't want to upgrade this bike but restore using original parts. As you pointed out, the bb will come out and the tubing will be cleaned, lightly sanded, and greased with ParkTool SuperGrip. This has cup-and-cone Japan made SAKAE brand bb. As much as I love to keep the original, I also enjoy Shimano cartridge type bottom brackets. I need to make the decision during my work whether keep the original (with new loose bearings + marine grease) or replace with a new cartridge bb. I also like those dust-cap integrated hex-type crack arm fixing bolts and I can use those if I upgrade to cartridge bb. But if you tell me the keep the original bb, I will strongly consider. A photo from internet for an identical bb as mine. Of course, mine will be in a rough shape after being used for 30+ years with no service.
ser_gio is offline  
Old 12-01-22, 12:55 PM
  #32  
zandoval 
Senior Member
 
zandoval's Avatar
 
Join Date: May 2010
Location: Bastrop Texas
Posts: 3,823

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

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 686 Post(s)
Liked 1,141 Times in 736 Posts
I am late to post to this party... Ha... I have not really considered a 1992 bicycle an old bike but looks like the time has come. So now it can be hard to find the proper seat post size on a 92 era bike. How time fly's. Just think of trying to find the seat post size of a 70s era bike after you have salvaged the frame from a junk pile. Yep, that's a challenge. Even if ya know what seat post is supposed to go into it. Here's the way I do it and remember its not "The Way but just A Way..."
Clean it up and sand it down inside and out
Give it an eye ball top to bottom
Is it round, inside diameter lower, inside diameter upper, fix what you can
Get a pipe and wrap tape around it to get the diameter that fits comfortably upper and lower
Use that diameter to get or make the seat post you need
Using sand paper to adjust the diameter of your seat post is no big deal if the seat tube has been properly cleaned and prepped
Don't forget to use a liberal amount of quality anti-seize compound from top to bottom on that seat tube before your final assembly
Hope to see you on the forum as ya go along and thanks for educating me that bikes made in the 90s are now having the same problems as those made in the 70s...
__________________
No matter where your at... There you are... Δf:=f(1/2)-f(-1/2)
zandoval is offline  
Old 12-01-22, 12:59 PM
  #33  
zandoval 
Senior Member
 
zandoval's Avatar
 
Join Date: May 2010
Location: Bastrop Texas
Posts: 3,823

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

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 686 Post(s)
Liked 1,141 Times in 736 Posts
Originally Posted by ser_gio
Of course, mine will be in a rough shape after being used for 30+ years with no service...
Possibly, but these buggers can be pretty tough. Especially the ones made in Japan. Chances are it will be just fine. For a bottom bracket on a Mountain Bike I would prefer a Cartridge instead of loose balls. But still... Loose Balls Rule...
__________________
No matter where your at... There you are... Δf:=f(1/2)-f(-1/2)

Last edited by zandoval; 12-01-22 at 01:02 PM.
zandoval is offline  
Old 12-07-22, 10:42 AM
  #34  
grumpus
Full Member
 
grumpus's Avatar
 
Join Date: Apr 2016
Posts: 385
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 147 Post(s)
Liked 120 Times in 99 Posts
Originally Posted by maddog34
Bore gauges are EXPENSIVE and rarely seen in anything but Machine shops.
You've not looked on Ali Express, have you? 18-35 mm dial bore gauge £34.46 with free shipping (that's not the cheapest one). Almost certainly not toolmaker quality, but probably plenty good for a bike workshop. I may try one myself, I've had some good stuff from Ali Express (and some total junk).
grumpus is offline  

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 or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.