Ti frames more durable?

[Rocketman58]

I have a Ti hardtail MTB. I am running a longer travel
fork than it was designed for (105mm vs 80mm). It is
working great for me, but is this going to place more
stress on the frame? Is a Ti frame stronger than an
aluminum or steel frame?

 

[Zog The Undenia]

rocketman58 wrote:

> I have a Ti hardtail MTB. I am running a longer travel
> fork than it was designed for (105mm vs 80mm). It is
> working great for me, but is this going to place more
> stress on the frame? Is a Ti frame stronger than an
> aluminum or steel frame?

Ti actually has a fatigue limit [1], but it's lower than
steel so may be exceeded by the normal stresses that the
frame will experience when ridden. Without some very clever
finite element analysis you can't tell whether the frame
will last for ever in "normal use". Having said that, a
badly built steel frame - including some very expensive ones
- can also crack after only a few years.

Strength is a separate issue from fatigue and depends on the
gauge of tubes and the design as well as the material used.
Everything else being equal, 3/2.5 Ti is a bit *weaker* than
Reynolds 531. See
http://www.reynoldsusa.com/tubing/tubing.html.

[1] a particular stress, below which the material can
survive an infinite number of cycles without failing

 

[Alex Rodriguez]

In article
<[email protected]>,
[email protected] says...
>I have a Ti hardtail MTB. I am running a longer travel
>fork than it was designed for (105mm vs 80mm). It is
>working great for me, but is this going to place more
>stress on the frame?

Shouldn't be a big deal at all.

>Is a Ti frame stronger than an aluminum or steel frame?

material alone does not make one frame stronger than
another. The design is much, much, much more important.
-------------
Alex

 

[Chris]

"rocketman58" <[email protected]> wrote in message
news:[email protected]...
> I have a Ti hardtail MTB. I am running a longer travel
> fork than it was designed for (105mm vs 80mm). It is
> working great for me, but is this going to place more
> stress on the frame? Is a Ti frame stronger than an
> aluminum or steel frame?

80 to 105 isn't a big deal (look at all the adjustable forks
like Blacks, TALAS, and SIDs that cover this range) but like
others have mentioned, it's the design of the
headtube/toptube/downtube junction that'll make it you or
break you.

You *should* be fine, but the mtb gear rule of thumb is, if
you're nervous about it, then you shouldn't be riding it.

Chris

 

[Dave Lehnen]

Zog The Undeniable wrote:

> Ti actually has a fatigue limit [1], but it's lower than
> steel so may be exceeded by the normal stresses that the
> frame will experience when ridden. Without some very
> clever finite element analysis you can't tell whether the
> frame will last for ever in "normal use". Having said
> that, a badly built steel frame - including some very
> expensive ones - can also crack after only a few years.
>
> Strength is a separate issue from fatigue and depends on
> the gauge of tubes and the design as well as the material
> used. Everything else being equal, 3/2.5 Ti is a bit
> *weaker* than Reynolds 531. See
> http://www.reynoldsusa.com/tubing/tubing.html.
>
>
> [1] a particular stress, below which the material can
> survive an infinite number of cycles without failing

The site you reference actually shows 3/2.5 Ti having a very
slightly higher fatigue limit than 531, (and a slightly
lower ultimate tensile strength) but both of these with a
much lower limit than air-hardened 853. It's misleading in
any case, not accounting for the typically greater diameter
and wall thickness Ti bike tubing would usually have.

Dave Lehnen

 

[Back At Home Ph]

> You *should* be fine, but the mtb gear rule of thumb
> is, if you're nervous about it, then you shouldn't be
> riding it.

Let me just say, people are dumb. Some people have no idea
their QRs are OFF and flopping around

Phil

 

[Rocketman58]

[email protected] (rocketman58) wrote in message news:<[email protected]>...
> I have a Ti hardtail MTB. I am running a longer travel
> fork than it was designed for (105mm vs 80mm). It is
> working great for me, but is this going to place more
> stress on the frame? Is a Ti frame stronger than an
> aluminum or steel frame?

I have a Black 100-120 fork that is set to about 105mm. The
spring rate changes with the travel - 105mm is just right
for me. The frame is very well constructed with standard
size tubing (for Ti). There is no extra reinforcement at the
head tube. I do not ride very agressive, and do not jump.
The fork is set soft for comfort. I feel pretty secure with
this setup, I just thought I would ask...

PS: I'm using the 100-120 fork because it is very plush and
I already had it sitting around.