Ti frames more durable?

Discussion in 'Cycling Equipment' started by Rocketman58, Mar 8, 2004.

  1. Rocketman58

    Rocketman58 Guest

    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?
     
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  2. 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
     
  3. 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
     
  4. Chris

    Chris Guest

    "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
     
  5. Dave Lehnen

    Dave Lehnen Guest

    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
     
  6. > 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
     
  7. Rocketman58

    Rocketman58 Guest

    [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.
     
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