Retrobike Forum Index

It is currently Mon Dec 05, 2016 12:01 pm

* Login   * Register * Search  * FAQ



Post new topic Reply to topic  [ 6 posts ] 
Author Message
PostPosted: Mon Oct 29, 2012 6:43 pm 
Dirt Disciple

Joined: Wed Feb 04, 2009 3:09 pm
Posts: 78
Location: London
This is probably a classic dumb question.

I need to get a seat post for a cheapo Fausto Coppi frame I’m putting together for the winter. With a ruler, it looks to my eyes like the seat tube is 26.5mm. I don’t have either a 26.4 or a 26.6 post to test it with. Does anyone here have a neat trick for getting a more accurate measurement? Equally, any views on which side it’s better to err?

D.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Oct 29, 2012 9:40 pm 
Retro Guru
User avatar

Joined: Mon Mar 26, 2012 5:21 pm
Posts: 589
Vernier calipers will give you a more accurate measurement, but 0.2mm is easy to misread and you could easily get both measurements on an old tube (in my experience).

The only way (I know of) to be sure is to actually fit a post.

I've just this evening taken the plunge with a 26.4mm Selcoff: if it doesn't fit then I'm happy to let you have it on a sale-or-return basis or even just a trial basis: I'll keep you posted.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Oct 30, 2012 11:47 am 
Retro Guru
User avatar

Joined: Wed Apr 25, 2012 2:08 pm
Posts: 2185
Location: Shrewsbury
You could use a piece of paper to measure the circumference although there's only 1/2mm difference so you'll have to be accurate. If you cut the length so that the two ends meet up perfectly then measure the length of paper. A 26.4mm post will be 82.93mm a 26.6mm will be 83.56mm.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Oct 30, 2012 12:25 pm 
retrobike rider
retrobike rider
User avatar

Joined: Fri Aug 08, 2008 2:36 pm
Posts: 16747
Location: Yorkshire, England
50/50 chance there

BUT it'll only tighten up smaller, not larger*.
You need to measure inside, not the clamping part.
So I would err on 26.4mm



* assuming a too small post hasn't previously been used and the clamping part is now slightly bent, leading to a larger post being needed and/or two clamping marks down the seatpost .


Top
 Profile  
 
 Post subject:
PostPosted: Tue Oct 30, 2012 7:16 pm 
Dirt Disciple

Joined: Wed Feb 04, 2009 3:09 pm
Posts: 78
Location: London
Thanks all - much appreciated.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Oct 30, 2012 10:15 pm 
Retro Guru

Joined: Tue Feb 02, 2010 6:11 pm
Posts: 1844
Location: wellingborough
be carefull as trying to squeaze a 26.6 into a 26.4 could soon lead to a very stuck seat post , so try smaller size first .


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: kingbling, non-fixie, syvid_974 and 19 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

About Us

Follow Retrobike

Other cool stuff

All content © 2005-2015 Retrobike unless otherwise stated.
Cookies Policy.
bikedeals - the best bike deals in one place
FatCOGS - Fat Chance Owner's Group

Powered by phpBB® Forum Software © phpBB Group