609 bike questions [photo]

John B. wrote:

The internally tapered steerer tube means
that the tube is stronger at the bottom of
the tube where it is attached to the fork
crown, or fork blades. Where the maximum load
will be.

Yes, but what is the advantage of having less
tube where the minimum load is? Weight?

--
underground experts united
http://user.it.uu.se/~embe8573

On 7/10/2017 11:39 AM, Emanuel Berg wrote:
John B. wrote:

The internally tapered steerer tube means
that the tube is stronger at the bottom of
the tube where it is attached to the fork
crown, or fork blades. Where the maximum load
will be.

Yes, but what is the advantage of having less
tube where the minimum load is? Weight?


For a standard column, BSC for example[1], the ID is 22.2mm
the thread is 1" (25.4mm) and impact failures are usually at
the crown. Some relatively inexpensive steerers have a
sleeve brazed in at the bottom but top quality steel
steerers are butted:

https://raleighsb4059.files.wordpres...ston.jpg?w=750

Which means that a small frame size will have limited depth
for a quill stem as Mr Slocumb noted.

[1] Metric ID is 22.0mm with an m25x1 thread. Or was,
anyway; I'm pretty sure there are no current metric forks in
production.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Mon, 10 Jul 2017 18:39:37 +0200, Emanuel Berg
wrote:

John B. wrote:

The internally tapered steerer tube means
that the tube is stronger at the bottom of
the tube where it is attached to the fork
crown, or fork blades. Where the maximum load
will be.

Yes, but what is the advantage of having less
tube where the minimum load is? Weight?

Think or the taper as providing "enough" strength rather then "less"
or "more".

But yes, what one might call "up-market" bicycle tubing is normally
"butted" tubes, in other words, the ends where it is brazed or welded
together is thicker then the middle portion of the tube and this is
done to reduce weight.
--
Cheers,

John B.

John B. wrote:

Think or the taper as providing "enough"
strength rather then "less" or "more".

But yes, what one might call "up-market"
bicycle tubing is normally "butted" tubes, in
other words, the ends where it is brazed or
welded together is thicker then the middle
portion of the tube and this is done to
reduce weight.

OK, now we are discussing two things, right?

taper = gradually smaller toward one end, as in
a cone?

butted = looks the same from the outside, only
walls are thicker or thinner, i.e. not the
same ID all thru the tube?

If so... these ones are not taper, probably
they are not butted either.

These bikes were never exactly up-market.
But solid bikes. People bought them and
expected to have them for a long time.

That is why they are still around and I can
make them solid again without that much effort.

--
underground experts united
http://user.it.uu.se/~embe8573

On Tue, 11 Jul 2017 05:57:20 +0200, Emanuel Berg
wrote:

John B. wrote:

Think or the taper as providing "enough"
strength rather then "less" or "more".

But yes, what one might call "up-market"
bicycle tubing is normally "butted" tubes, in
other words, the ends where it is brazed or
welded together is thicker then the middle
portion of the tube and this is done to
reduce weight.

OK, now we are discussing two things, right?

taper = gradually smaller toward one end, as in
a cone?

butted = looks the same from the outside, only
walls are thicker or thinner, i.e. not the
same ID all thru the tube?

If so... these ones are not taper, probably
they are not butted either.

:-) Well in order to change wall thickness there is a taper. In fact
didn't I mention the dimensions? About a 30mm taper from the thick to
the thin wall.

These bikes were never exactly up-market.
But solid bikes. People bought them and
expected to have them for a long time.


If I remember correctly I mentioned a tapered steerer tube as
something that you might encounter, not that all tubes were tapered.
But I have a, probably Japanese built, road bike that is, again
probably, 30 years old that originally had 26 by 1-3/8ths inch tires
which likely places it in the lower classes of road bikes, and it has
a tapered steerer tube.

30 years might be a long time in some people's experience :-)
--
Cheers,

John B.

John B. wrote:

:-) Well in order to change wall thickness
there is a taper. In fact didn't I mention
the dimensions? About a 30mm taper from the
thick to the thin wall.

....?

OK, now there is a terminology issue.

When I Google 'taper steerer tube' I get photos
of forks where the top part looks like the low
half of a long cone.

But when I listen to you it sounds like butting
with different sized walls?

Is butting implicit with taper to make room
within the tube?

Or is butting = taper when it is done on the
inside? If so, the "cone part" would be
something that actually isn't there but is
absent from the tube.

Or are they to different things which can be
used separately or in combination?

--
underground experts united
http://user.it.uu.se/~embe8573

On 7/11/2017 1:10 PM, Emanuel Berg wrote:
John B. wrote:

:-) Well in order to change wall thickness
there is a taper. In fact didn't I mention
the dimensions? About a 30mm taper from the
thick to the thin wall.

...?

OK, now there is a terminology issue.

When I Google 'taper steerer tube' I get photos
of forks where the top part looks like the low
half of a long cone.

But when I listen to you it sounds like butting
with different sized walls?

Is butting implicit with taper to make room
within the tube?

Or is butting = taper when it is done on the
inside? If so, the "cone part" would be
something that actually isn't there but is
absent from the tube.

Or are they to different things which can be
used separately or in combination?


As I wrote yesterday with image link:

"For a standard column, BSC for example[1], the ID is 22.2mm
the thread is 1" (25.4mm) and impact failures are usually at
the crown. Some relatively inexpensive steerers have a
sleeve brazed in at the bottom but top quality steel
steerers are butted:

https://raleighsb4059.files.wordpres...ston.jpg?w=750

Which means that a small frame size will have limited depth
for a quill stem as Mr Slocumb noted.

[1] Metric ID is 22.0mm with an m25x1 thread. Or was,
anyway; I'm pretty sure there are no current metric forks in
production. "

A tapered head tube and tapered fork column is something
different altogether.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

AMuzi wrote:

As I wrote yesterday with image link ...

Yes, I read it, of course, but I think all the
trees got in front of the forest...

A tapered head tube and tapered fork column
is something different altogether.

OK, a tapered head tube is a butted tube.

And a tapered fork column looks like half
a cone shooting up from the crown?

--
underground experts united
http://user.it.uu.se/~embe8573

On Tue, 11 Jul 2017 20:10:16 +0200, Emanuel Berg
wrote:

John B. wrote:

:-) Well in order to change wall thickness
there is a taper. In fact didn't I mention
the dimensions? About a 30mm taper from the
thick to the thin wall.

...?

OK, now there is a terminology issue.

When I Google 'taper steerer tube' I get photos
of forks where the top part looks like the low
half of a long cone.

But when I listen to you it sounds like butting
with different sized walls?

Is butting implicit with taper to make room
within the tube?

Or is butting = taper when it is done on the
inside? If so, the "cone part" would be
something that actually isn't there but is
absent from the tube.

Or are they to different things which can be
used separately or in combination?

See: http://www.framebuilding.com/Forks.htm
the last three or four items on the list.
--
Cheers,

John B.