measuring seatpost diameter

davek said:

I suppose this is really more of a general maths/engineering question
than a cycling one, but the context is cycling, so here goes...

Say I want to replace a suspension seatpost with a non-suspension
seatpost. How do I know what size seatpost to get? In other words, is
there an easy way to accurately measure the diameter of the current
seatpost? Or should I expect to be able to find some clue imprinted
somewhere on the post itself?

you should indeed, most posts have the diameter embossed near the
bottom. Alternatively measure the circumference and divide by 3.1419
(pi)

davek said:

I suppose this is really more of a general maths/engineering question
than a cycling one, but the context is cycling, so here goes...

Say I want to replace a suspension seatpost with a non-suspension
seatpost. How do I know what size seatpost to get? In other words, is
there an easy way to accurately measure the diameter of the current
seatpost? Or should I expect to be able to find some clue imprinted
somewhere on the post itself?

Quoted message said:

Vernier calipers do it for me, but I bet it's marked somewhere below the
min. insertion line.

On 27 Jan 2005 09:58:18 -0800, "davek" <[email hidden]>

Quoted message said:

seatpost. How do I know what size seatpost to get? In other words, is
there an easy way to accurately measure the diameter of the current
seatpost? Or should I expect to be able to find some clue imprinted
somewhere on the post itself?

AASHTA (possibly)

http://www.sheldonbrown.com/seatpost_sizes.html

MartinM said:

most posts have the diameter embossed near the
bottom.

Only if you leave the saddle off ;-)

Tony

davek said:

I suppose this is really more of a general maths/engineering question
than a cycling one, but the context is cycling, so here goes...

Say I want to replace a suspension seatpost with a non-suspension
seatpost. How do I know what size seatpost to get? In other words, is
there an easy way to accurately measure the diameter of the current
seatpost? Or should I expect to be able to find some clue imprinted
somewhere on the post itself?

I use a vernier caliper.

If your not familiar with how these work, this might help
http://www.phy.ntnu.edu.tw/java/ruler/vernier.html

--
Joe * If I cannot be free I'll be cheap

"MartinM" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

davek said:

I suppose this is really more of a general maths/engineering question
than a cycling one, but the context is cycling, so here goes...

Say I want to replace a suspension seatpost with a non-suspension
seatpost. How do I know what size seatpost to get? In other words, is
there an easy way to accurately measure the diameter of the current
seatpost? Or should I expect to be able to find some clue imprinted
somewhere on the post itself?

you should indeed, most posts have the diameter embossed near the
bottom. Alternatively measure the circumference and divide by 3.1419
(pi)

Has someone been tinkering with the value of a universal constant again?
When I was at school pi was 3.1416 (to 4 decimal points)

On Thu, 27 Jan 2005 19:25:50 +0000 (UTC), "me" <[email hidden]>

Quoted message said:

"MartinM" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

davek said:

I suppose this is really more of a general maths/engineering question
than a cycling one, but the context is cycling, so here goes...

Say I want to replace a suspension seatpost with a non-suspension
seatpost. How do I know what size seatpost to get? In other words, is
there an easy way to accurately measure the diameter of the current
seatpost? Or should I expect to be able to find some clue imprinted
somewhere on the post itself?

you should indeed, most posts have the diameter embossed near the
bottom. Alternatively measure the circumference and divide by 3.1419
(pi)

Has someone been tinkering with the value of a universal constant again?
When I was at school pi was 3.1416 (to 4 decimal points)

Pi was once destined to be set at 3.2
http://www.bbc.co.uk/radio4/science/5numbers2.shtml
(The whole series, along with "Another 5 Numbers) is quite good)

On 27/1/05 7:39 pm, in article [email hidden],

Richard Bates said:

On Thu, 27 Jan 2005 19:25:50 +0000 (UTC), "me" <[email hidden]>

Quoted message said:

"MartinM" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

davek wrote:
> I suppose this is really more of a general maths/engineering question
> than a cycling one, but the context is cycling, so here goes...
>
> Say I want to replace a suspension seatpost with a non-suspension
> seatpost. How do I know what size seatpost to get? In other words, is
> there an easy way to accurately measure the diameter of the current
> seatpost? Or should I expect to be able to find some clue imprinted
> somewhere on the post itself?

you should indeed, most posts have the diameter embossed near the
bottom. Alternatively measure the circumference and divide by 3.1419
(pi)

Has someone been tinkering with the value of a universal constant again?
When I was at school pi was 3.1416 (to 4 decimal points)

Pi was once destined to be set at 3.2
http://www.bbc.co.uk/radio4/science/5numbers2.shtml
(The whole series, along with "Another 5 Numbers) is quite good)

Pi is round, crusty on top and filled with meat and gravy.

Oh no, thats t.

...d

me said:

"MartinM" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

davek said:

I suppose this is really more of a general maths/engineering question
than a cycling one, but the context is cycling, so here goes...

Say I want to replace a suspension seatpost with a non-suspension
seatpost. How do I know what size seatpost to get? In other words, is
there an easy way to accurately measure the diameter of the current
seatpost? Or should I expect to be able to find some clue imprinted
somewhere on the post itself?

you should indeed, most posts have the diameter embossed near the
bottom. Alternatively measure the circumference and divide by 3.1419
(pi)

Has someone been tinkering with the value of a universal constant again?
When I was at school pi was 3.1416 (to 4 decimal points)

Here's a fine UL about a law to make pi = 3
http://www.snopes.com/religion/pi.htm

--
Joe * If I cannot be free I'll be cheap

me said:

Has someone been tinkering with the value of a universal constant again?
When I was at school pi was 3.1416 (to 4 decimal points)

Yes pi is actually 3 on the authority of the Bible (1 Kings 7, 23) [1]
or 3.2 on the authority of the Indiana House of Representatives (Section
I, House Bill No. 246, 1897)[2]

Tony

[1]And he made a molten sea, ten cubits from the one brim to the other:
it was round all about, and his height was five cubits: and a line of
thirty cubits did compass it about
[2]Be it enacted by the General Assembly of the State of Indiana:
....that the ratio of the diameter and circumference is as five-fourths
to four;

Tony Raven said:

me said:

Has someone been tinkering with the value of a universal constant again?
When I was at school pi was 3.1416 (to 4 decimal points)

Yes pi is actually 3 on the authority of the Bible (1 Kings 7, 23) [1]

Pi is 3 anyway[1]. What is your problem with maths?

Quoted message said:

[1]And he made a molten sea, ten cubits from the one brim to the other:
it was round all about, and his height was five cubits: and a line of
thirty cubits did compass it about

...d

[1] To one significant figure.

"davek" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I suppose this is really more of a general maths/engineering question
than a cycling one, but the context is cycling, so here goes...

Say I want to replace a suspension seatpost with a non-suspension
seatpost. How do I know what size seatpost to get? In other words, is
there an easy way to accurately measure the diameter of the current
seatpost? Or should I expect to be able to find some clue imprinted
somewhere on the post itself?

tia,

d.

The replacement seatpost must fit the frames seat tube accurately.
If you don't have a vernier caliper then a good bike shop should be able to
measure it for you.

David Martin said:

Tony Raven said:

me said:

Has someone been tinkering with the value of a universal constant again?
When I was at school pi was 3.1416 (to 4 decimal points)

Yes pi is actually 3 on the authority of the Bible (1 Kings 7, 23) [1]

Pi is 3 anyway[1]. What is your problem with maths?

Quoted message said:

[1]And he made a molten sea, ten cubits from the one brim to the other:
it was round all about, and his height was five cubits: and a line of
thirty cubits did compass it about

...d

[1] To one significant figure.

What is wrong with your maths? According to the Bible Pi is 3 to at
least one decimal place (30/10).

Tony

"Rudge" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"davek" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I suppose this is really more of a general maths/engineering question
than a cycling one, but the context is cycling, so here goes...

OK OK I got the 4th decimal place wrong (or even missed it out, hangs head
in shame)
Can anyone remember what that other supposed value of pi, 22/7 equates to?
(without resort to a calculator or the web)

BTW was Sheldon around even before Ptolemy ;-)

"Now look son, just work it out, you have 9 calculators and you take 6
calculators away, how many calculators have you got left over"

Tony Raven said:

JLB said:

Here's a fine UL about a law to make pi = 3
http://www.snopes.com/religion/pi.htm

Snopes may be right about Alabama but in Indiana they did legislate in
the House of Representatives to make pi=3.2 although its implimentation
was indefinitely postponed (but not to my knowledge cancelled) by the
Senate. [snip]

Snopes mentions that too, briefly, foot of the page I cited.

--
Joe * If I cannot be free I'll be cheap

Tony Raven said:

David Martin said:

Tony Raven said:

me wrote:

> Has someone been tinkering with the value of a universal constant again?
> When I was at school pi was 3.1416 (to 4 decimal points)
>
>

Yes pi is actually 3 on the authority of the Bible (1 Kings 7, 23) [1]

Pi is 3 anyway[1]. What is your problem with maths?

Quoted message said:

[1]And he made a molten sea, ten cubits from the one brim to the other:
it was round all about, and his height was five cubits: and a line of
thirty cubits did compass it about

...d

[1] To one significant figure.

What is wrong with your maths? According to the Bible Pi is 3 to at
least one decimal place (30/10).

Tony

30 is 31.4 to one significant figure. 10 is 10.55 to one significant figure.

What was wrong with my maths?

...d

me said:

Has someone been tinkering with the value of a universal constant again?
When I was at school pi was 3.1416 (to 4 decimal points)

Very easy to remember --

how I want a drink, alcoholic of course, after the heavy chapters
involving quantum mechanics

count the letters:
3.14159265358979

A few more in various languages are here:

http://www.geocities.com/CapeCanaveral/Lab/3550/pimnem.htm

Mike

MartinM said:

"Rudge" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"davek" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I suppose this is really more of a general maths/engineering question
than a cycling one, but the context is cycling, so here goes...

OK OK I got the 4th decimal place wrong (or even missed it out, hangs head
in shame)
Can anyone remember what that other supposed value of pi, 22/7 equates to?
(without resort to a calculator or the web)

Yes. 22/7 is a useful approximation to pi, not a value of it. Mental
arithmetic says it comes out in decimal as 3.142857...... recurring. But
there's no point converting it to decimal. The reason it's useful is
that it consists of the ratio of two numbers that are simple to use in
back-of-an-envelope calculations, unlike great long decimals.

--
Joe * If I cannot be free I'll be cheap

"Mike Causer" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

count the letters:
3.14159265358979

they are digits ;-)