measuring seat tube size

what's the best way to measure my seat tube so that i can get the correct seat post size?

i know that the LBS has some cone-shaped thing, but my LBS isn't that local and i'd like to order the correct size post for my almost done fixie.

 

Ben Tsprocket writes:

> i know that the LBS has some cone-shaped thing, but my LBS isn't that local and i'd like to order
> the correct size post for my almost done fixie.

Cycle over to Radio Shack and borrow one of their electric measuring calipers.

Or buy one off ebay for about $12, as I did. Like one of these:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2325019586&category=29525

Pretty interesting what you can measure once you have one of these gizmos

Lee

 

Do you have any 'machinist' buddies with a micrometer or a caliper?

Do you or your friends have any seatposts that you can try in the hole?

Lewis.

...................... bent_sprocket <[email protected]> wrote in message
news:<[email protected]>...
> what's the best way to measure my seat tube so that i can get the correct seat post size?
>
> i know that the LBS has some cone-shaped thing, but my LBS isn't that local and i'd like to order
> the correct size post for my almost done fixie.

 

On Sat, 31 May 2003 00:30:17 +0950, bent_sprocket wrote:

> what's the best way to measure my seat tube so that i can get the correct seat post size?
>
> i know that the LBS has some cone-shaped thing, but my LBS isn't that local and i'd like to order
> the correct size post for my almost done fixie.

I presume you don't have a decent caliper, which would be the best way. But you probably have
another bike. Try the seatpost from that. You may get lucky, or at least have an idea of what
the size is.

--

David L. Johnson

__o | What is objectionable, and what is dangerous about extremists is _`\(,_ | not that they are
extreme, but that they are intolerant. (_)/ (_) | --Robert F. Kennedy

 

On Sat, 31 May 2003 00:30:17 +0950, bent_sprocket wrote:

> what's the best way to measure my seat tube so that i can get the correct seat post size?
>
> i know that the LBS has some cone-shaped thing, but my LBS isn't that local and i'd like to order
> the correct size post for my almost done fixie.

If you have the original seat post look at it, some seat posts have the size stamped on them.
Otherwise you can't beat calipers, got some metric ones at Home Depot for ~$12.

 

"bent_sprocket" <[email protected]> wrote in message
news:[email protected]...
> what's the best way to measure my seat tube so that i can get the correct seat post size?
>
> i know that the LBS has some cone-shaped thing, but my LBS isn't that local and i'd like to order
> the correct size post for my almost done fixie.

Seat tube ID are notoriously difficult to measure with a caliper due to out-of-roundness and
the fact that that oval variance can easily be greater than the difference from one size to the
next (0.2mm).

Ideally, you should find the actual specification and clean the bore with a parallel-blade
adjustable reamer ( referenced by the mysteriously anonymous "ant" here recently).

Failing that, another effective method is to slip in seatposts until one is found which slides
neatly with full contact and then confirm that by tryng the next larger size which should start with
difficulty but be obviously too tight.

On a beaten-up seat cluster, slipping a slightly smaller post in about 30mm and pressing toward the
back of the bicycle will usually cure dented/crushed seat binder problems. You end up with little
contact in the first inch or so until the bolt is tightened, so you don't gouge up the new post with
the mangled edge near the slit.
--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971