Seatposts: Usable Lengths?

(Pete Cresswell) said:

Sounds to me like I should re-spec the frame to have a
22" seat tube

instead of

Quoted message said:

21.

Heck, why not longer? With the seatpost lengths you mention,
I can't imagine you'll have any difficulty with standover
clearance.

--
Dave dvt at psu dot edu

RE/

Quoted message said:

Wow, I guess that will require a pile of spacers between
the headset and the stem. That is if your steering tube is
300mm long like the new ones I've seen. Not a problem if
it's steel and you are OK with the look. Are you talking
about a suspension fork? They kick the front end up so you
could reduce the number of spacers on top. Anyhow, the
setup sounds a bit contrived. Either I'm missing something
or you are getting the frame for the right price. No
matter. I wish you good luck and I sincerely hope you enjoy
your bike.

The steering tube will be 6.4" which, on my hardtail, allows
mountint a stem at the very top of an uncut fork with a max
spacer stack of 1.25".

"Contrived" in that I've got right-bell-curve dimensions:
37.5" inseam, size 15 feet...and so-forth.
--
PeteCresswell

RE/

Quoted message said:

I can understand 3 ft long seatposts and vertical stems on
an off the shelf frame, but custom?

There's an upper limit on steering tubes.

As far as the seatpost goes, seems to me like it's one of
those "you pays your money and you takes your choice"
things. More seatpost/lower standover....less
seatpost/greater standover.

My current bike is an Ellsworth ISIS with one of those "Y"
frames....max standover...and it's saved my butt a couple of
times, so I'm prejudiced in favor of minimum
standover....but I just don't want to get into a situation
where I need some kind of designer seatpost fo achieve it.
If Thompson's 410 will do the job, I'll be happy with
that...and it sounds like that's the case.
--
PeteCresswell

(Pete Cresswell) said:

RE/

Quoted message said:

I can understand 3 ft long seatposts and vertical stems on
an off the shelf frame, but custom?

There's an upper limit on steering tubes.

In your previous post you mention 1.25" of spacers. Why not
1.25" more of headtube instead of spacers? It doesn't sound
like you're interested in lowering your bars, and even if
you wanted to couldn't you get a flatter stem?

Quoted message said:

As far as the seatpost goes, seems to me like it's one of
those "you pays your money and you takes your choice"
things. More seatpost/lower standover....less
seatpost/greater standover

My current bike is an Ellsworth ISIS with one of those "Y"
frames....max standover...and it's saved my butt a couple
of times, so I'm prejudiced in favor of minimum
standover....

Either you're a lot more hardcore than you let on in a.m-b
or I think you're favoring standover clearance too much.

Greg

Quoted message said:

Either you're a lot more hardcore than you let on in a.m-b
or I think you're favoring standover clearance too much.

There's a third option: really, really clumsy....

Also, the shorter the seat tube, the more chance I can lend
the bike to a normal person...-)

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

Quoted message said:

Quoted message said:

Either you're a lot more hardcore than you let on in
a.m-b or I think you're favoring standover clearance
too much.

There's a third option: really, really clumsy....

Also, the shorter the seat tube, the more chance I can
lend the bike to a normal person...-)

Well, there is a lot to say for that!

Greg

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

Quoted message said:

I need 32" from the seatpost's clip to the center of the
BB spindle.

A frame I'm thinking about is only 21".

Anybody know what length post I'd need to get a full 12"
(an extra inch just for margin of error...) of actual,
usable extension from the top of the seat tube to the clip
where the saddle rails lie?

Seems like post specs are something like LOA...but
not quite.

My saddle-to-BB dimension is right about the same as yours
and I've been using a RaceFace XY 400 mm seatpost on a 21"
Schwinn Homegrown Full Suspension frame for several years
now with no problems. (My weight has been as high as 260lbs
in that time period too.) This frame uses a pretty small
26.8mm dia. post and up until I got the RF XY, I bent every
other post I tried (original, Kalloy, Ritchey Comp, Titec
XC) within six months. I've got plenty of seatpost down
inside the frame. The XY posts also have a pretty large 1"
offset and one of the easiest saddle angle/horizontal
adjustments I've used.

I would have used a Thomson post on the above bike but I
needed as much offset as I could get and their setback post
was only available in a 250mm for a 26.8" dia. I can say
that the only seatpost a friend of mine, who's about 6' 6"
and 245 lbs, did not bend on the 19" aluminum hardtail he
was riding for a few years was a straight Thomson 410mm post
(it's a 26.8" too.) I finally convinced him he needed a
larger frame when I came across a new Specialized 23"
aluminum hardtail frame and built it up for him to try. We
used a Titec Knock post on that bike - it seems pretty
strong and is available in a 390 mm length.

[email hidden] (PeteCresswell) wrote in message news:<[email hidden]>...

Quoted message said:

[...] Anybody know what length post I'd need to get a full
12" (an extra inch just for margin of error...) of actual,
usable extension from the top of the seat tube to the clip
where the saddle rails lie?

Seems like post specs are something like LOA...but
not quite.

So in conclusion, a seatpost should be inserted at least 4
inches and completely past the top tube welds? Yes? No? Same
rules for a 150lb rider as a 250? Same rules for off-road as
on-road? Thanks.

galt-<< So in conclusion, a seatpost should be inserted at
least 4 inches and completely past the top tube welds? Yes?
No? >><BR><BR>

Minimum-twice the top tube width below the bottom of
the top tube.

So a 1.5cm top tube, 3cm below the bottom of the top tube.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St.
Boulder, CO, 80302
(303)440-3535 vecchios.comvecchios.comOpen ↗ "Ruote convenzionali
costruite eccezionalmente bene"