Reliability of Steerer Materials

Hey,

As I mentioned in an earlier post I'm in the market for a new carbon
fork. I'm focusing mostly on forks with aluminum steerers but I'm also
interested in forks with Ti steerers.

The more I learn about titanium and its use in the bicycle industry, the
less flawless of a material it seems to be. Weight limits on Ti pedal
spindles, flexy feel, arguably not a good material to use with certain
fastners, etc. It's still a compelling material to study however, and
I'm interested in knowing if it makes for a good steer tube material
(i.e., does it tend to have tight torque specs. for the clamp bolts,
what's it longevity like, does it have its own unique dangers when
cutting the tube to length, etc.).

All and all if I'm concerned about strength, reliability, and safety the
most am I better off with an aluminum steerer or ti. Thanks,

D. Ualp

D. Ualp wrote:

Hey,

As I mentioned in an earlier post I'm in the market for a new carbon
fork. I'm focusing mostly on forks with aluminum steerers but I'm also
interested in forks with Ti steerers.

The more I learn about titanium and its use in the bicycle industry, the
less flawless of a material it seems to be. Weight limits on Ti pedal
spindles, flexy feel, arguably not a good material to use with certain
fastners, etc. It's still a compelling material to study however, and
I'm interested in knowing if it makes for a good steer tube material
(i.e., does it tend to have tight torque specs. for the clamp bolts,
what's it longevity like, does it have its own unique dangers when
cutting the tube to length, etc.).

All and all if I'm concerned about strength, reliability, and safety the
most am I better off with an aluminum steerer or ti. Thanks,

Ti is between aluminium and steel in weight, strength and stiffness
terms. Like steel, it has a fatigue limit (a cyclical stress limit
below which it should last indefinitely).

Its main advantage in a steerer tube would be good corrosion resistance.
You can make a nice frame from Ti if the tube diameters are specified
to make the most of the material (somewhere between Al and steel tube
diameters), but as the dimensions of a steerer tube are limited to 1" or
1 1/8", there's no real room for manoeuvre.

Ti is *notoriously* hard to cut and will blunt saw blades very quickly.

On Sun, 08 Aug 2004 00:57:37 -0700, "D. Ualp"
wrote:

Hey,

As I mentioned in an earlier post I'm in the market for a new carbon
fork. I'm focusing mostly on forks with aluminum steerers but I'm also
interested in forks with Ti steerers.

D. Ualp

Did I miss something? Why don't you like carbon steerers?


Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

"D. Ualp" wrote:

As I mentioned in an earlier post I'm in the market for a new carbon
fork. I'm focusing mostly on forks with aluminum steerers but I'm also
interested in forks with Ti steerers.

Neither of those materials are as good a choice as dumb old steel for
a steer tube. The reason for this is that steel is stiffest of the
three, which matters a great deal when the size of a component is
fixed, as in a steer tube. Other frame tubes can be enlarged to take
advantage of the low density of Ti or aluminum, but a steer tube can
only be one certain diameter, dictated by the headset standard being
used.

In order to win back some of the stiffness that was lost in going to
an aluminum or Ti steerer, it must be made thicker, which negates much
of the weight advantage of those materials. By the time you are at
the same weight as the steel part, the stiffness is still not equal to
that of the steel part. One example of this effect is that a one inch
steel steer tube is slightly stiffer than a solid one inch aluminum
rod of the same length, despite being quite a bit lighter. To attain
the same stiffness with the same wall thickness as the steel steerer,
the aluminum one would have to be 1.4" in diameter--which means that
using a 1.125" steerer still doesn't help much.

If you want flex built into the front end of your bike, let it be in
the fork legs, where it won't interfere with lateral stability or
proper operation of the headset bearings. The steerer should be
stiff.

Chalo Colina

On 8 Aug 2004 16:04:28 -0700, (Chalo) wrote:

"D. Ualp" wrote:

As I mentioned in an earlier post I'm in the market for a new carbon
fork. I'm focusing mostly on forks with aluminum steerers but I'm also
interested in forks with Ti steerers.

Neither of those materials are as good a choice as dumb old steel for
a steer tube. The reason for this is that steel is stiffest of the
three, which matters a great deal when the size of a component is
fixed, as in a steer tube.

I don't understand how a steerer tube can flex much at all. Do they?

JT

On Sun, 08 Aug 2004 19:19:25 -0400, John Forrest Tomlinson
wrote:

On 8 Aug 2004 16:04:28 -0700, (Chalo) wrote:

"D. Ualp" wrote:

As I mentioned in an earlier post I'm in the market for a new carbon
fork. I'm focusing mostly on forks with aluminum steerers but I'm also
interested in forks with Ti steerers.

Neither of those materials are as good a choice as dumb old steel for
a steer tube. The reason for this is that steel is stiffest of the
three, which matters a great deal when the size of a component is
fixed, as in a steer tube.

I don't understand how a steerer tube can flex much at all. Do they?

JT

Here's a quick drawing;

top lower wheel
bearing bearing axle
V V
===================================
/\

Now push back (down on the drawing) on the axle (equivalent to braking
load) and you can see the fork will take a curve which moves the
middle of the steerer tube forward (up on the drawing) from it's
neutral position. Reverse the arrows to show the equivalent of the
load imposed by the weight of the bike/rider

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

John Forrest Tomlinson wrote in message . ..
On 8 Aug 2004 16:04:28 -0700, (Chalo) wrote:

"D. Ualp" wrote:

As I mentioned in an earlier post I'm in the market for a new carbon
fork. I'm focusing mostly on forks with aluminum steerers but I'm also
interested in forks with Ti steerers.

Neither of those materials are as good a choice as dumb old steel for
a steer tube. The reason for this is that steel is stiffest of the
three, which matters a great deal when the size of a component is
fixed, as in a steer tube.

I don't understand how a steerer tube can flex much at all. Do they?

JT

It could be my imagination but I've had a Ti steerer fork that flexed
so much I swore I could see the stem move down a few degrees when I
used the front cantilever brakes when doing a test before riding.

On 8 Aug 2004 22:28:16 -0700, (Woogoogle) wrote:

John Forrest Tomlinson wrote in message . ..
On 8 Aug 2004 16:04:28 -0700, (Chalo) wrote:

"D. Ualp" wrote:

As I mentioned in an earlier post I'm in the market for a new carbon
fork. I'm focusing mostly on forks with aluminum steerers but I'm also
interested in forks with Ti steerers.

Neither of those materials are as good a choice as dumb old steel for
a steer tube. The reason for this is that steel is stiffest of the
three, which matters a great deal when the size of a component is
fixed, as in a steer tube.

I don't understand how a steerer tube can flex much at all. Do they?

JT

It could be my imagination but I've had a Ti steerer fork that flexed
so much I swore I could see the stem move down a few degrees when I
used the front cantilever brakes when doing a test before riding.

That was the stem flexing under weight transfer :-) If the steerer was
flexing uder brake load, your bars should actually have risen slightly


Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

John Forrest Tomlinson wrote:

I don't understand how a steerer tube can flex much at all. Do they?

Oh you bet. Sight down your fork while you grab some front brakes and
see for yourself.

I have bent far too many forks to keep count of, and most of them bent
above the headset crown race. In order to fail there it must first be
flexed to its failure point.

Chalo Colina

On 9 Aug 2004 02:16:31 -0700, (Chalo) wrote:

John Forrest Tomlinson wrote:

I don't understand how a steerer tube can flex much at all. Do they?

Oh you bet. Sight down your fork while you grab some front brakes and
see for yourself.

I can't see that precisely due to the forces on my head and body while
braking.

I wonder how you can see that well. It doesnt' sound plausible.

JT