UK and Europe · Public discussion

Seat Post size?

Msa · 2004-02-03T22:03:55+00:00

A few days ago I finally managed to purchase a second hand road bike for commuting. I've spent the past 2 nights stripping it down, adjusting, cleaning, truing wheels, and replacing cables etc. Unfortunately, the saddle has become 'welded' to the seatpost and the Allen bolt has completely burred over. The bolt sits in a tight recess so I can't cut through it, and I've tried all other means of getting it off. I didn't like the saddle anyway, so the easiest option is to buy a new post for about a tenner (for once I'm not being a weight weenie!). The old post has no size on it and using a steel rule the seat tube looks to be 26mm, and the seat post looks to be 25mm. The bike is a Peugeot, steel frame. Not sure of the year, but it's running a 7 speed Shimano free hub if that's any indication? Any ideas on the right size post? I've checked the database on Sheldons site, and my bike is not mentioned..although Peugeot is, the most common being 26.4. I'm sure this would be too big. Ideas please people! -- Mark (MSA) This post is packaged by intellectual weight, not volume. Some settling of contents may have occurred during transmission

Started by Msa · 3 February 2004 · Last activity 4 February 2004 · 11 posts · 1,035 views

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01 / Original postSeat Post size?Msa · 3 Feb 2004 02 / This pagePosts 1–11Page 1 of 1 · chronological order 03 / Latest replyPost #11Zog The Undenia · 4 Feb 2004

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Original section: UK and Europe
Published: 3 February 2004
Last activity: 4 February 2004
Original author: Msa
Posts: 11
Discussion status: Public discussion
Total views: 1,035
Views / 30 days: 0
Topics: Frame sizing Steel frames

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Original post
Msa
Archived post

3 February 2004, 22:03 UTC #1

A few days ago I finally managed to purchase a second hand road bike for commuting. I've spent the
past 2 nights stripping it down, adjusting, cleaning, truing wheels, and replacing cables etc.
Unfortunately, the saddle has become 'welded' to the seatpost and the Allen bolt has completely
burred over. The bolt sits in a tight recess so I can't cut through it, and I've tried all other
means of getting it off.
I didn't like the saddle anyway, so the easiest option is to buy a new post for about a tenner (for
once I'm not being a weight weenie!). The old post has no size on it and using a steel rule the seat
tube looks to be 26mm, and the seat post looks to be 25mm.
The bike is a Peugeot, steel frame. Not sure of the year, but it's running a 7 speed Shimano free
hub if that's any indication?
Any ideas on the right size post? I've checked the database on Sheldons site, and my bike is not
mentioned..although Peugeot is, the most common being 26.4. I'm sure this would be too big.
Ideas please people!
--
Mark (MSA) This post is packaged by intellectual weight, not volume. Some settling of contents may
have occurred during transmission

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Nobody760
Archived post

3 February 2004, 23:02 UTC #2

Use an Engineers gauge on the existing seat post. Read off the correct measurement.
If you don't know what and engineers gauge looks like it can best be described as an F looking tool
where the bottom bar of the F moves on the vertical bar which has an accurate gauge on it. Read off
that measurement. Failing that take it all down to yer local bike shop and get them to do it.

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Vernon Levy
Archived post

3 February 2004, 23:02 UTC #3

Quoted message said:
Use an Engineers gauge on the existing seat post. Read off the correct measurement.
You don't need anything more sophisticated than a strip of paper wrapped around the post. Mark off
where the paper overlaps itself for the first time, remove and measure between the end of the paper
and the mark. Divide this by 3.14 to get the diameter of the seat tube. It's a tad more accurate
than trying to use a ruler by itself.
Trust me I'm a teacher :-)
Vernon in Leeds

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Just Zis Guy
Archived post

4 February 2004, 00:02 UTC #4

MSA said:
using a steel rule the seat tube looks to be 26mm, and the seat post looks to be 25mm.
You need a much more accurate figure than that. The buggers come in .05mm increments ;-)
Guy
===
May contain traces of irony. Contents liable to settle after posting.
chapmancentral.demon.co.ukchapmancentral.demon.co.uk

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Anonymous
Archived post

4 February 2004, 14:04 UTC #5

"nobody760" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:
Use an Engineers gauge on the existing seat post. Read off the correct measurement.
If you don't know what and engineers gauge looks like it can best be described as an F looking
tool where the bottom bar of the F moves

on
Quoted message said:
the vertical bar which has an accurate gauge on it. Read off that measurement. Failing that take
it all down to yer local bike shop and get them to do it.
aka vernier calipers? (ok, you didn't mention the vernier bit, but that's what makes them useful)
cheers, clive

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Just Zis Guy
Archived post

4 February 2004, 14:04 UTC #6

"]news:[email hidden]...
Quoted message said:
aka vernier calipers?
aka verynear calipers, on account of how many people can't /quite/ read the Vernier properly ;-)
--
Guy
===
WARNING: may contain traces of irony. Contents may settle after posting.
chapmancentral.co.ukchapmancentral.co.uk

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Anonymous
Archived post

4 February 2004, 14:04 UTC #7

"Just zis Guy, you know?" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:
"]news:[email hidden]...
Quoted message said:
aka vernier calipers?
aka verynear calipers, on account of how many people can't /quite/ read

the
Quoted message said:
Vernier properly ;-)
:-)
As an aside, does anybody else think that the vernier concept is exceedingly great?
cheers, clive

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Just Zis Guy
Archived post

4 February 2004, 14:04 UTC #8

"]news:[email hidden]...
Quoted message said:
As an aside, does anybody else think that the vernier concept is

exceedingly
Quoted message said:
great?
It is one of those simple ideas that works perfectly.
--
Guy
===
WARNING: may contain traces of irony. Contents may settle after posting.
chapmancentral.co.ukchapmancentral.co.uk

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John Hearns
Archived post

4 February 2004, 14:04 UTC #9

Clive George said:

As an aside, does anybody else think that the vernier concept is exceedingly great?

Yup. Back when I did lecturing and lab demonstrating I had to explain to students how to use vernier
calipers. (And of course someone once had to tell me!)
I once bought a set of vernier calipers in one of the pound shops. Made of plastic. I thought they
were a great buy, but obviously wouldn't trust them greatly. Sadly haven't got them any more.

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Mseries
Archived post

4 February 2004, 15:03 UTC #10

Clive George said:
"Just zis Guy, you know?" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:
Quoted message said:
"]news:[email hidden]...
Quoted message said:
aka vernier calipers?
aka verynear calipers, on account of how many people can't /quite/ read the Vernier properly ;-)
:-)
As an aside, does anybody else think that the vernier concept is exceedingly great?
cheers, clive
Yes. I have some and I learned how to use them when I was at school. Unfortunately I forgot how to
read down to the 100th of a mil. I came across a fun website that has a java applet showing calipers
moving and explaining how to read them !
--
The Reply & From email addresses are checked rarely. mseries.freeserve.co.ukmseries.freeserve.co.uk

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Zog The Undenia
Archived post

4 February 2004, 19:03 UTC #11

vernon levy said:
Quoted message said:
Use an Engineers gauge on the existing seat post. Read off the correct measurement.
You don't need anything more sophisticated than a strip of paper wrapped around the post. Mark off
where the paper overlaps itself for the first time, remove and measure between the end of the
paper and the mark. Divide this by 3.14 to get the diameter of the seat tube. It's a tad more
accurate than trying to use a ruler by itself.
Trust me I'm a teacher :-)
I doubt that would split a 27.2 and a 27.4 post ;-)
If the frame is made from Reynolds 531C it should have a 27.2mm post. Silver brazed 531C can take a
27.4mm post if the seat tube isn't reamed, but this is incredibly rare.

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