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Thread: Frame Questions

  1. #1
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    Frame Questions

    So I have a Giant Sedona, it's from the early 90's but Im not entirely sure, it was my dads bike and I fixed it up.
    its seems to be study, but I had a question. is there any way to tell about the frame material?

    it says Quad Butted Cro-moly.....i dunno what that means. I mean it's decently light but it's not (not heavy) either. (if I could find the date on my bike it'd be easier, any ideas?)

    I had heard alot about aluminum frame's. now here's my worry. I dont want the frame to fatigue over time or break or w/e cause I know there much weaker than steel/titanium etc.

    but then again i only ride around the city, and "occasionally" take it a little off the beaten path (dirt/grassy road etc....hey it's kentucky lol)

    IF my frame was aluminum, would that cause any harm to it over time, or when they mean "frame" bending do they mean like if ur jumping off rocks and hardcore mountain biking with it?

    Thanks!

    OH BTW does anyone know if the giants in particular the giant sedona's are a good brand/type or bike?

    thx

  2. #2
    Your mom
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    Cro-Moly is steel (I think chromium/molybdenum, the metals they mix in with the iron). It's standard stuff. Quad butted is nice-ish. Don't worry about it at all; get out and ride!

  3. #3
    Gone, but not forgotten Sheldon Brown's Avatar
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    Quote Originally Posted by MercenaryFH View Post
    So I have a Giant Sedona, it's from the early 90's but Im not entirely sure, it was my dads bike and I fixed it up.
    its seems to be study, but I had a question. is there any way to tell about the frame material?

    it says Quad Butted Cro-moly.....i dunno what that means. I mean it's decently light but it's not (not heavy) either. (if I could find the date on my bike it'd be easier, any ideas?)

    I had heard alot about aluminum frame's. now here's my worry. I dont want the frame to fatigue over time or break or w/e cause I know there much weaker than steel/titanium etc.

    but then again i only ride around the city, and "occasionally" take it a little off the beaten path (dirt/grassy road etc....hey it's kentucky lol)

    OH BTW does anyone know if the giants in particular the giant sedona's are a good brand/type or bike?
    These were very nice bikes, definitely a keeper. Your dad has good taste.

    Quote Originally Posted by tellyho View Post
    Cro-Moly is steel (I think chromium/molybdenum, the metals they mix in with the iron). It's standard stuff. Quad butted is nice-ish. Don't worry about it at all; get out and ride!
    Good for you, you are one of the rare few who can spell molybdenum! (I'm sure that's the main reason for abbreviating it to "moly" ;-)

    Quad butted is more than "nice-ish", it's as good as it gets.

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  4. #4
    Making a kilometer blurry waterrockets's Avatar
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    Yep, it's steel. I commute, MTB, train, tandem, and race on steel bikes. You're good to go -- go work on the motor!

    Giants are a popular brand with some ProTour sponsorship (Giant bikes race in the Tour De France). I have several friends racing on them.

    FWIW, Aluminum is in no more danger of failure than any other frame material. All good bikes are built to withstand the expected loads and still be as light as possible, given the budget. Riding off-road on light bumps won't challenge the frame much, but be careful with the wheels -- they're much more susceptible to rough road problems.

  5. #5
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    Oh. so theirs no such thing as cro-moly quad butted aluminum eh(do most steel bikes use that?), im kinda glad it's steel. I mean i dont hardcore offroad but hell I like to take my bike on the dusty trail. i just heard that aluminum it will like bend and break over time?
    but giants good quality im assuming :-D

    thanks so much guys

  6. #6
    Gone, but not forgotten Sheldon Brown's Avatar
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    Quote Originally Posted by MercenaryFH View Post
    Oh. so theirs no such thing as cro-moly quad butted aluminum eh
    Nope, no more than wood steel. Totally different materials.

    Quote Originally Posted by MercenaryFH View Post
    i just heard that aluminum it will like bend and break over time?
    Sounds like you have been listening to unscrupulous or ignorant salesmen! See: http://sheldonbrown.com/frame-materials

    Sheldon "Metal Is Good" Brown
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  7. #7
    Craig A. Lebowitz lebowitz's Avatar
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    the problem with aluminum is that is actually can not bend much over time without failing. It can bend very little before deforming permanently (like an aluminum can) and never returning to the original shape. So the failure case is usually one traumatic incident that wrecks it structually.

    Steel can bend and be bent back and that is essentially what makes it resilient and desirable as a frame material (along with its vibration absorption property)

    Quote Originally Posted by MercenaryFH View Post
    i just heard that aluminum it will like bend and break over time?

  8. #8
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    oh I see. So....for like "riding" purposes like Im going to be doing, I mean even tho my bike is steel im just curious, but for slight offroad but mostly city riding (assuming u dont get hit by a car/in an accident with your bike) would aluminum hold up over a long time? or eventually fatigue by being just ridden on in the city and kinda break that way?

  9. #9
    biked well well biked's Avatar
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    Quote Originally Posted by MercenaryFH View Post
    oh I see. So....for like "riding" purposes like Im going to be doing, I mean even tho my bike is steel im just curious, but for slight offroad but mostly city riding (assuming u dont get hit by a car/in an accident with your bike) would aluminum hold up over a long time? or eventually fatigue by being just ridden on in the city and kinda break that way?
    You shouldn't worry so much about it, it's all in the design of the individual bike. Here's an example of an aluminum framed bike that will hold up to some serious off road abuse:
    http://www.intensecycles.com/web/m3.html

    And here's a steel framed bike that won't hold up to any off road abuse:
    http://www.lemondbikes.com/bikes/roa...eel/sarthe.php

    They're both nice bikes in their own way, but obviously it's not about frame material, but about what each is designed for-

  10. #10
    Mr. Dopolina Bob Dopolina's Avatar
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    I used to sell those bike right around the time your model seems to come from. In fact we had one as a shop bike. That thing was beat on by everyone and just kept going. I personally hucked it off a cliff one time and fished it out of a tree (after a serious ejection from the top of a big drop) another time. Trued up the wheels and lent it to someone else the next weekend.

    Someones probably still riding it.

  11. #11
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    Quote Originally Posted by lebowitz View Post
    the problem with aluminum is that is actually can not bend much over time without failing. It can bend very little before deforming permanently (like an aluminum can) and never returning to the original shape. So the failure case is usually one traumatic incident that wrecks it structually.

    Steel can bend and be bent back and that is essentially what makes it resilient and desirable as a frame material (along with its vibration absorption property)
    You are confusing stiffness (the ability to resist bending) and elastic deformation (stress that doesn't permanantly bend a structure) with ductility (the ability to bend permanantly without failure).

    What you are incorrectly describing is "fatigue life" which is how many stress cycles, at a stress level below that needed to permanantly deform the material, a given material will take before it fails.

    Steel and Ti, if kept below a stress threshold, have an effectively infinite fatigue life. Aluminum, even at low stress, has a finite fatigue life and will crack sooner or later. That said, the practical life of most aluminum frames is so long that failure is a non-issue unless the frame is badly abused. BTW, you can also ruin a steel frame if you are abusive enough.

    To the OP: as the others have said, your frame is a high strength steel and the "butting" means the tubing wall thickness is varied to reduce weight while maintaining strength where needed. It is not aluminum in any way.

  12. #12
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    ah indeed it seems to be a VERY nice bike. i'd prolly buy steel more now, but it's so cheap..it makes me thing the bike is poorer quality, like the steel sedona is only like 300$ now, and the aluminum is like 500......lol?

  13. #13
    Craig A. Lebowitz lebowitz's Avatar
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    Quote Originally Posted by HillRider View Post
    You are confusing stiffness (the ability to resist bending) and elastic deformation (stress that doesn't permanantly bend a structure) with ductility (the ability to bend permanantly without failure).

    What you are incorrectly describing is "fatigue life" which is how many stress cycles, at a stress level below that needed to permanantly deform the material, a given material will take before it fails.

    Steel and Ti, if kept below a stress threshold, have an effectively infinite fatigue life. Aluminum, even at low stress, has a finite fatigue life and will crack sooner or later. That said, the practical life of most aluminum frames is so long that failure is a non-issue unless the frame is badly abused. BTW, you can also ruin a steel frame if you are abusive enough.

    To the OP: as the others have said, your frame is a high strength steel and the "butting" means the tubing wall thickness is varied to reduce weight while maintaining strength where needed. It is not aluminum in any way.

    thanks for setting me straight

  14. #14
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    i need to get some pics of this bike :-D

  15. #15
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    btw how hard are rear derailers to put on, i wouldnt mind upgrading mine, it works fine but ya know

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