Seat Post Length

I was looking at some bikes on the web, and some appear to have very
long seat posts sticking out of the frame. The bike which I have now
the seat post does not come out that far. Is the seat post that long
because of the style of the bike, and the frame is smaller? My first
impression is that the ride or bike would not be stable, and that seat
post might fall out, but I am sure that is my imagination.

Thanks

Tom

wrote in message
ps.com...
I was looking at some bikes on the web, and some appear to have very
long seat posts sticking out of the frame. The bike which I have now
the seat post does not come out that far. Is the seat post that long
because of the style of the bike, and the frame is smaller? My first
impression is that the ride or bike would not be stable, and that seat
post might fall out, but I am sure that is my imagination.

Thanks

Tom

No Tom, there is a minimum insertion line that keeps all that from
happening.
My guess is a smaller bike is lighter and stronger so people might want a
longer seat post.
Good trade off unless you also have to put a longer headset on which will
weigh you down anyway.

On 21 Apr 2007 02:21:55 -0700, "
wrote:

I was looking at some bikes on the web, and some appear to have very
long seat posts sticking out of the frame. The bike which I have now
the seat post does not come out that far. Is the seat post that long
because of the style of the bike, and the frame is smaller? My first
impression is that the ride or bike would not be stable, and that seat
post might fall out, but I am sure that is my imagination.

Thanks

Tom

Anyone that got used to bikes before sloping top tubes has to adjust
to the fact that those bikes have, in general, much longer seat posts
- and then they make them out of carbon so the old farts can worry
that much more...

Curtis L. Russell
Odenton, MD (USA)
Just someone on two wheels...

On Apr 21, 4:21 am, "
wrote:
I was looking at some bikes on the web, and some appear to have very
long seat posts sticking out of the frame. The bike which I have now
the seat post does not come out that far. Is the seat post that long
because of the style of the bike, and the frame is smaller? My first
impression is that the ride or bike would not be stable, and that seat
post might fall out, but I am sure that is my imagination.

There is an increasing number of road bikes featuring "compact
geometry," which incorporates a sloping top tube and results in the
need for more exposed length of seatpost. This may be what you're
noticing. The frames and seatposts are designed for this.

If the bike is properly sized and fitted to the rider, there's no
reason a compact frame will make a noticeable difference in the ride
quality, in and of itself.

R

nash wrote:

My guess is a smaller bike is lighter and stronger so people might want a
longer seat post.

That is what they want you to guess. The real reason is simpler; the
fewer sizes they have to provide, the easier and cheaper their
distribution costs will be.

How a fashion is sold bears little resemblance to any real advantage.

A smaller frame is clearly not stronger than a larger one, for the same
rider. Leverage on the junctions of the tube is worse for the smaller
frame. If not, then the real advantage would be a bike with one tube,
not a separate top and downtube. Those bikes exist (usually they are
folders, so optimized for portability, not strength/weight), but they do
have a really beefy tube, and for a reason.

--

David L. Johnson

If all economists were laid end to end, they would not reach
a conclusion. -- George Bernard Shaw

Don't worry too much about your seat post length, as long as you don't have
to extended it above the limit mark ( a line around the post about 2.5 in
from the end.
you need at least this much in the seat tube for strength! God forbid it
braking with you sitting on it!

"rdclark" wrote in message
ups.com...
On Apr 21, 4:21 am, "
wrote:
I was looking at some bikes on the web, and some appear to have very
long seat posts sticking out of the frame. The bike which I have now
the seat post does not come out that far. Is the seat post that long
because of the style of the bike, and the frame is smaller? My first
impression is that the ride or bike would not be stable, and that seat
post might fall out, but I am sure that is my imagination.

There is an increasing number of road bikes featuring "compact
geometry," which incorporates a sloping top tube and results in the
need for more exposed length of seatpost. This may be what you're
noticing. The frames and seatposts are designed for this.

If the bike is properly sized and fitted to the rider, there's no
reason a compact frame will make a noticeable difference in the ride
quality, in and of itself.

R