Saddle Rail Failures

[Harris]

Two questions on saddle rails:

1) Are tubular saddle rails more likely to fail than solid rails?

2) Would tubular steel rails be more reliable than solid Ti?

Thanks, Art Harris

 

[Dion Dock]

1) yes
2) It doesn't matter. Nothing is more important than saving weight.

-Dion

"Harris" <[email protected]> wrote in message
news:[email protected]...
> Two questions on saddle rails:
>
> 1) Are tubular saddle rails more likely to fail than solid rails?
>
> 2) Would tubular steel rails be more reliable than solid Ti?
>
> Thanks, Art Harris

 

[A Muzi]

"Harris" <[email protected]> wrote in message
news:[email protected]...
> Two questions on saddle rails:
>
> 1) Are tubular saddle rails more likely to fail than solid rails?
>
> 2) Would tubular steel rails be more reliable than solid Ti?

That leaves too many variables, like what kind of steel, how thick and how well made (uniform)
is the tube?

Generally Ti is far inferior to steel here AEBE, but all else is seldom equal.

Titanium rail failures are common yet steel failures, even among a vastly larger sample with vast
quality differences, are not common.
--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971

 

[Frank Krygowski]

A Muzi wrote:
>
> "Harris" <[email protected]> wrote in message
> news:[email protected]...
> > Two questions on saddle rails:
> >
> > 1) Are tubular saddle rails more likely to fail than solid rails?
> >
> > 2) Would tubular steel rails be more reliable than solid Ti?
>
> That leaves too many variables, like what kind of steel, how thick and how well made (uniform) is
> the tube?
>
> Generally Ti is far inferior to steel here AEBE, but all else is seldom equal.
>
> Titanium rail failures are common yet steel failures, even among a vastly larger sample with vast
> quality differences, are not common.

I second that.

Here in my office, I've got a broken titanium saddle rail. When the time comes to explain metal
fagigue, I pass it around. Nice classic example, with pretty "beach marks."

--
Frank Krygowski [email protected]

 

[Steve Palincsar]

On Thu, 13 Feb 2003 12:36:47 -0500, Dion Dock wrote:

> 1) yes
> 2) It doesn't matter. Nothing is more important than saving weight.
>

Then why, I wonder, bother with that heavy nasty old saddle at all? Just leave it off entirely, and
think of the grams saved. ;-)

 

[Richard Ney]

"A Muzi" <[email protected]> wrote

> > Two questions on saddle rails:
> >
> > 1) Are tubular saddle rails more likely to fail than solid rails?
> >
> > 2) Would tubular steel rails be more reliable than solid Ti?
>
> That leaves too many variables, like what kind of steel, how thick and how well made (uniform) is
> the tube?
>
> Generally Ti is far inferior to steel here AEBE, but all else is seldom equal.
>
> Titanium rail failures are common yet steel failures, even among a vastly larger sample with vast
> quality differences, are not common.

What's the failure mode? A bend, kink, or something catastrophic?

 

[Harris]

"Richard Ney" wrote:

Art Harris wrote:
> > > Two questions on saddle rails:
> > >
> > > 1) Are tubular saddle rails more likely to fail than solid rails?
> > >
> > > 2) Would tubular steel rails be more reliable than solid Ti?
> >
A. Muzi wrote:
> > That leaves too many variables, like what kind of steel, how thick and
how
> > well made (uniform) is the tube?
> >
> > Generally Ti is far inferior to steel here AEBE, but all else is seldom equal.
> >
> > Titanium rail failures are common yet steel failures, even among a
vastly
> > larger sample with vast quality differences, are not common.
>
> What's the failure mode? A bend, kink, or something catastrophic?

Shear failure. The reason for my question is that most current saddles are not available with solid
steel rails. I'm looking for the next strongest type. It gets confusing when you start seeing terms
like Vanadium and Manganese.

A booklet that came with my Rolls Classic saddle shows the labeling that Selle San Marco uses. They
use "C" for steel, "M" for Cr-Mo (not manganese), and "T" for titanium. Since Cr-Mo IS steel this is
very confusing. I THINK they use "M" to mean tubular Cr-Mo, and "C" to mean solid steel.

I had a hollow Manganese rail fail once, so I would definitely avoid that. I'm trying to determine
the relative strength of hollow Cr-Mo vs. solid Ti since those seem to be the most available types.

Art Harris

 

[Robin Hubert]

It seems to me that all the saddle rail failures I've seen are usually due to the saddle being too
far back (as in, all the way) on the rails and/or abuse.

Robin Hubert

 

[A Muzi]

> > > Two questions on saddle rails:
> > > 1) Are tubular saddle rails more likely to fail than solid rails?
> > > 2) Would tubular steel rails be more reliable than solid Ti?

<[email protected]> wrote
> > That leaves too many variables, like what kind of steel, how thick and
how
> > well made (uniform) is the tube? Generally Ti is far inferior to steel here AEBE, but all else
> > is seldom equal. Titanium rail failures are common yet steel failures, even among a
vastly
> > larger sample with vast quality differences, are not common.

"Richard Ney" <[email protected]> wrote in message
news:[email protected]...
> What's the failure mode? A bend, kink, or something catastrophic?

A rail just snaps, directly behind the clamp..

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

 

[Frank Krygowski]

Richard Ney wrote:
>
> What's the failure mode? A bend, kink, or something catastrophic?

Again, for this one it was fatigue in bending, directly behind the clamp. That means a small crack
formed at a high-stress area, gradually worked its way through the solid rail, and the last little
bit hanging on snapped in two on a bump. It's catastrophic.

The owner stopped, picked up the pieces, and rode home standing.

--
Frank Krygowski [email protected]

 

[Harris]

"Frank Krygowski" wrote:

> Again, for this one it was fatigue in bending, directly behind the clamp. That means a small crack
> formed at a high-stress area, gradually worked its way through the solid rail, and the last little
> bit hanging on snapped in two on a bump. It's catastrophic.
>
> The owner stopped, picked up the pieces, and rode home standing.

On a group ride I was on, one of the riders broke a rail. He was able to position the broken part
inside the seat post clamp and finish the ride sitting.

Art Harris

 

[Benjamin Weiner]

Art Harris <[email protected]> wrote:
> "Richard Ney" wrote:
> A. Muzi wrote:

> > > Titanium rail failures are common yet steel failures, even among a vastly larger sample with
> > > vast quality differences, are not common.
> > What's the failure mode? A bend, kink, or something catastrophic?

> Shear failure. The reason for my question is that most current saddles are not available with
> solid steel rails. I'm looking for the next strongest type. It gets confusing when you start
> seeing terms like Vanadium and Manganese.

Marketing speak. Vanadium and manganese are alloying elements in steel (ever buy a "chrome vanadium"
screwdriver?). For example, Reynolds 531 is manganese-molybdenum steel (as opposed to Cr-Mo which is
chromium-molybdenum). I have a Selle Italia Sphere with "FeC alloy" rails. Duh, every decent steel
has iron and carbon in it.

> A booklet that came with my Rolls Classic saddle shows the labeling that Selle San Marco uses.
> They use "C" for steel, "M" for Cr-Mo (not manganese), and "T" for titanium. Since Cr-Mo IS steel
> this is very confusing. I THINK they use "M" to mean tubular Cr-Mo, and "C" to mean solid steel.

As with bikes, Cr-Mo probably indicates stronger than generic steel, but then they can make the
tubing walls thinner. I don't know that the "C" ones are solid - solid steel rails would be
rather heavy.

> I had a hollow Manganese rail fail once, so I would definitely avoid that. I'm trying to
> determine the relative strength of hollow Cr-Mo vs. solid Ti since those seem to be the most
> available types.

I think you can assume that reasonable steels will be stronger than Ti but what you don't know is
the relative quality of design/manufacture. Anything can fail once. Did it really just shear right
off, no bending first? Could there have been a stress riser from the seatpost clamp?

I hear from this thread that Ti rail failures are common. That's a bit worrisome. Any common
features among the failures (mountain bikes, large riders, poorly designed seatpost clamps, seat all
the way back on the rails)?

 

[Frank Krygowski]

Benjamin Weiner wrote:
>
> Duh, every decent steel has iron and carbon in it.

So do all the indecent steels!

--
Frank Krygowski [email protected]

 

[Phil]

> I hear from this thread that Ti rail failures are common. That's a bit worrisome. Any common
> features among the failures (mountain bikes, large riders, poorly designed seatpost clamps, seat
> all the way back on the rails)?

I'm 140lbs. Bent an 8mm solid steel rail during a MTB race on a BMX saddle. Somewhat of a harsh
crash that gave me a bruise on my bum for a couple days afterwards. It sits on a 20 or 30-degree
slope to the side now.

Phil, Squid-in-Training

 

[Benjamin Weiner]

Harris <[email protected]> wrote:
> "Richard Ney" wrote:
> A. Muzi wrote:

> > > Titanium rail failures are common yet steel failures, even among a vastly larger sample with
> > > vast quality differences, are not common.
> > What's the failure mode? A bend, kink, or something catastrophic?

> Shear failure. The reason for my question is that most current saddles are not available with
> solid steel rails. I'm looking for the next strongest type. It gets confusing when you start
> seeing terms like Vanadium and Manganese.

Marketing speak. Vanadium and manganese are alloying elements in steel (ever buy a "chrome vanadium"
screwdriver?). For example, Reynolds 531 is manganese-molybdenum steel (as opposed to Cr-Mo which is
chromium-molybedenum). I have a Selle Italia here with "FeC alloy" rails. Duh, every decent steel
has iron and carbon in it.

> A booklet that came with my Rolls Classic saddle shows the labeling that Selle San Marco uses.
> They use "C" for steel, "M" for Cr-Mo (not manganese), and "T" for titanium. Since Cr-Mo IS steel
> this is very confusing. I THINK they use "M" to mean tubular Cr-Mo, and "C" to mean solid steel.

Cr-Mo is just one type of steel, stronger than generic. I don't know that the "C" ones are solid.

> I had a hollow Manganese rail fail once, so I would definitely avoid that. I'm trying to
> determine the relative strength of hollow Cr-Mo vs. solid Ti since those seem to be the most
> available types.

I think you can assume that reasonable steels will be stronger than Ti but what you don't know is
the relative quality of manufacture. Anything can fail once. Did it really just shear right off, no
bending first? Could there have been a stress riser from the seatpost clamp?

Andrew Muzi said Ti rail failures are common. Izzat so? That's a bit worrisome. Any common features
among the failures (mountain bikes, large riders, poorly designed seatpost clamps, seat all the way
back on the rails)?

 

[Sam Yorko]

Phil wrote:
>
> > I hear from this thread that Ti rail failures are common. That's a bit worrisome. Any common
> > features among the failures (mountain bikes, large riders, poorly designed seatpost clamps, seat
> > all the way back on the rails)?
>
> I'm 140lbs. Bent an 8mm solid steel rail during a MTB race on a BMX saddle. Somewhat of a harsh
> crash that gave me a bruise on my bum for a couple days afterwards. It sits on a 20 or 30-degree
> slope to the side now.
>
> Phil, Squid-in-Training

Let me get this straight: your bum now sits on a 20 or 30-degree slope to the side now? Um, wow.

Sam