GT seatpost diameter
Jeff Anderson
Hey all,
I've got a question for you. I'm need to replace the seatpost on my
1992 GT Karakoram. My LBS doesn't deal with GTs and apparently doesn't
care enough to find out what the called-for diameter is.
And, no, I don't have a micrometer, and I'm unwilling to "eye-it" with
a metric ruler. I don't want to miss by a tenth of a mm or two and have
slip-city.
Advice from someone who *knows* the size would be greatly appreciated.
An expensive post is going in this seat-tube, so a 'guess' is not really
acceptible. Don't mean to sound snotty, but you all realize the importance
of a correct fit here.
Thanks,
Jeff Anderson
Paul Warren Brieser
jda...@nwu.edu (Jeff Anderson) writes:
> I've got a question for you. I'm need to replace the seatpost on my
>1992 GT Karakoram. My LBS doesn't deal with GTs and apparently doesn't
>care enough to find out what the called-for diameter is.
> And, no, I don't have a micrometer, and I'm unwilling to "eye-it" with
>a metric ruler. I don't want to miss by a tenth of a mm or two and have
>slip-city.
If you still have the old post, try wrapping a piece of paper around
the outside of the post and measure the circumference of it that way (line
up the edges of the paper to make sure it's wrapped squarely). Divide by
3.141592653589793 to find the diameter...much more accurately than 'eyeballing'
with a ruler. Do a few measurements, average, compare to common seatpost
sizes, get out your credit card. This has worked for me twice now...
Not to insult here, but you _did_ check to see if the size is stamped
on the post itself, right? The cheapo Kalloy that was stock on my '93 K. has
the size on it (26.8).
>acceptible. Don't mean to sound snotty, but you all realize the importance
>of a correct fit here.
>Jeff Anderson
Hell, I thought the philosophy was: buy it big, hammer it in place,
save the weight of the seatpost QR. Or buy it small, then start a huge
flame war on r.b.tech about seatpost shims :-)
HTH
Paul Brieser pbri...@uiuc.edu
"The more I learn, the less I seem to know"
-Kicking Harold
jim frost
jda...@nwu.edu (Jeff Anderson) writes:
> I've got a question for you. I'm need to replace the seatpost on my
>1992 GT Karakoram. My LBS doesn't deal with GTs and apparently doesn't
>care enough to find out what the called-for diameter is.
> Advice from someone who *knows* the size would be greatly appreciated.
The most valuable lesson I learned in college was that the best way to
remember things is to remember how to look them up. That way you're
never wrong.
http://www.bikealog.com/ lists specifics on just about every bike on
the market. The Karakoram is 26.8mm.
>An expensive post is going in this seat-tube, so a 'guess' is not really
>acceptible. Don't mean to sound snotty, but you all realize the importance
>of a correct fit here.
Yup. Replaced my post a few months ago.
jim frost
ji...@world.std.com
--
http://world.std.com/~jimf
Joris D inhuurkracht
jda...@nwu.edu (Jeff Anderson) writes:
:
: Hey all,
:
: I've got a question for you. I'm need to replace the seatpost on my
: 1992 GT Karakoram. My LBS doesn't deal with GTs and apparently doesn't
: care enough to find out what the called-for diameter is.
: And, no, I don't have a micrometer, and I'm unwilling to "eye-it" with
: a metric ruler. I don't want to miss by a tenth of a mm or two and have
: slip-city.
If you have the old post, why don't you take it to the bikeshop and get
it measured there? Or is that too easy.
:
: Advice from someone who *knows* the size would be greatly appreciated.
: An expensive post is going in this seat-tube, so a 'guess' is not really
: acceptible. Don't mean to sound snotty, but you all realize the importance
: of a correct fit here.
:
: Thanks,
:
: Jeff Anderson
OTOH, if you dont have the old post, don't rely on claimed diameters,
because at my LBS, (which is a GT dealer) the diameters of their bike's
vary (mine is 27.0, others are 26.8 and they even had a 27.2 there). You
correctly state that .1mm can make a world of difference. In this case,
take the bike to the shop and have it measured. They should know how.
If they don't they can always try a few sizes (unless you plan to order
by mail).
-Dennis.
--
Ing. D.M. Joris, Software Specialist,
Philips CE/ASA Lab, tel: +31 40 27 33826
Building : SFJ-7 +31 40 27 35365
E-mail : jor...@iclab.ce.philips.nl fax: +31 40 27 37353
: g...@iaehv.nl (na 21:00 reply)
Homepage : http://www.iaehv.nl/users/gto
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jim frost
jor...@bcl1.seri.philips.nl (Joris D inhuurkracht) writes:
>OTOH, if you dont have the old post, don't rely on claimed diameters,
>because at my LBS, (which is a GT dealer) the diameters of their bike's
>vary (mine is 27.0, others are 26.8 and they even had a 27.2 there). You
>correctly state that .1mm can make a world of difference. In this case,
>take the bike to the shop and have it measured. They should know how.
GT's diameters vary between model lines, but not between individual
model instances. The Karakoram -- and in fact all of GT's steel MTB
frames -- has a 26.8" diameter. There are several diameters used on
their Al frames.
I didn't try to check out all of their Al models but the Backwoods has
a 26.8mm tube, the Avalanche 27.2, and the Zaskar, RTS, and LTS 27.0.
Joris D inhuurkracht
ji...@world.std.com (jim frost) writes:
: jor...@bcl1.seri.philips.nl (Joris D inhuurkracht) writes:
: >OTOH, if you dont have the old post, don't rely on claimed diameters,
: >because at my LBS, (which is a GT dealer) the diameters of their bike's
: >vary (mine is 27.0, others are 26.8 and they even had a 27.2 there). You
: >correctly state that .1mm can make a world of difference. In this case,
: >take the bike to the shop and have it measured. They should know how.
:
: GT's diameters vary between model lines, but not between individual
: model instances. The Karakoram -- and in fact all of GT's steel MTB
: frames -- has a 26.8" diameter. There are several diameters used on
: their Al frames.
My LBS must have a bad batch of frames then? I _was_ talking about
same models, same year. (although they were all alu, maybe the steel
frames are more consistent in seat-tube diam.).
:
: I didn't try to check out all of their Al models but the Backwoods has
: a 26.8mm tube, the Avalanche 27.2, and the Zaskar, RTS, and LTS 27.0.
I still think it is best to measure the diam. and not to rely on
specifications, IMHO. (and I'm a software engineer!)
:
: jim frost
: ji...@world.std.com
: --
: http://world.std.com/~jimf
-Dennis.
John Keeney
On Wed, 4 Sep 1996 20:52:16 GMT, ji...@world.std.com (jim frost) wrote:
> (snip) The Karakoram -- and in fact all of GT's steel MTB
>frames -- has a 26.8" diameter. (snip)
I have a GT Timberline purchased in June 1994 that has a 26.4 mm
seatpost (264 is stamped on post). I am the second owner of this bike;
but, the original owner says that it is the OEM seatpost. The LBS says
that GTs use a 26.8mm seatpost. I tried to call GT; but, they do not
answer the phone number printed on the catalog and owners manual.
The seatpost QR has to be very tight to hold the seatpost. Might I
have the wrong size seatpost? Is there a way to contact GT?
Thanks, John
jim frost
zucc...@ix.netcom.com (John Keeney) writes:
>I have a GT Timberline purchased in June 1994 that has a 26.4 mm
>seatpost (264 is stamped on post). I am the second owner of this bike;
>but, the original owner says that it is the OEM seatpost. The LBS says
>that GTs use a 26.8mm seatpost. I tried to call GT; but, they do not
>answer the phone number printed on the catalog and owners manual.
>The seatpost QR has to be very tight to hold the seatpost. Might I
>have the wrong size seatpost? Is there a way to contact GT?
Dunno how you should contact GT, but 26.8 is the right size for a
Timberline. If it's an original GT post it should have "GT" etched in
it, and the body of the seat clamp appears to be plastic. A 26.8 seat
post should fit very snugly. FWIW the GT post that came with mine (a
Tequesta) does not fit as well as the Control Tech I replaced it with,
although I didn't have any trouble getting it tight.