View Poll Results: Which Frame Material Best Suits DH MTN Biking

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  • Carbon

    33 36.26%
  • Aluminum

    45 49.45%
  • Chromoly Steel

    8 8.79%
  • Carbon/Aluminum Combo

    5 5.49%
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  1. #1
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    Frame Material Poll

    Solely based upon your personal experience and the experiences of close friends and associates, which frame material would you say best suits DH MTN biking:

    1) Carbon

    2) Aluminum

    3) Chromoly Steel

    4) Carbon/Aluminum Combo

    Also:

    What's your confidence level concerning carbon?

    On a scale from 1 to 5, how to you feel about the suspected quirkyness of carbon.

    * Give it a 1 for the absolute quirkiest and 5 for NOT quirky at all.

    1 - It's Extremely Quirky and everbody should know that by now!

    3 - Your still on the quirky fence (you still have your doubts).....

    5 - It's not quirky at all and stop questioning its integrity, dammit!
    Last edited by MoabiSlim; 08-18-2012 at 11:54 AM.
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  2. #2
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    Have spent a lot of time (riding and crashing) on both. Carbon fo sho.

    -More durable
    -Stronger
    -Stiffer
    -Lighter

    Resell value of carbon frames sucks, though - and probably rightfully so. Though carbon is more durable, it can be more difficult to tell if a frame is in fact damaged. With aluminum, oftentimes frame damage is quite apparent.

    Confidence Level:
    • 5 - If buying from reputable company (Santa Cruz/Spec/maybe Trek?)
    • 2 - If buying used
    Last edited by recitio; 08-18-2012 at 06:30 PM.

  3. #3
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    i think in a couple of year carbon will be by far the best

  4. #4
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    until someone starts making carbon stanchions...

  5. #5
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    Coming from a road bike background, steel is real. There are some killer new, strong light alloys out there that I would love to see being used for MTB's. I would love to feel that damping quality of steel on a DH bike. Hydro-formed tubes could be cool, too! JMHO

  6. #6
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    6.2lb road bike

    It's pretty cool to think that a Trek 9.9 with 2.7" DHFs + tubes, Deemax, Saint cranks and brakes, and double crown forks can tip the scales just over 32lb... Basically "too light," without compromising any core components for weight weenie stuff.

    If/when carbon wheels and cranks become more common / reliable, another pound or two may come off even that number - again without compromising anything. It's nuts.

  7. #7
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    Quote Originally Posted by recitio View Post
    Have spent a lot of time (riding and crashing) on both. Carbon fo sho.

    -More durable
    -Stronger
    -Stiffer
    -Lighter

    Resell value of carbon frames sucks, though - and probably rightfully so. Though carbon is more durable, it can be more difficult to tell if a frame is in fact damaged. With aluminum, oftentimes frame damage is quite apparent.

    Confidence Level:
    • 5 - If buying from reputable company (Santa Cruz/Spec/maybe Trek?)
    • 2 - If buying used
    I'm almost there with you!
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  8. #8
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    Quote Originally Posted by jakester29959 View Post
    i think in a couple of year carbon will be by far the best
    I don't know how long it will take. Perhaps a year. Perhaps 10 years. I'm not sure. What I do know for certain, is that the time is most definitely coming. I feel that we're so darned close!
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  9. #9
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    Quote Originally Posted by howardyudoing View Post
    until someone starts making carbon stanchions...
    I think that the problem with CF stanchions is more related to friction than anything else.

    Metal surfaces have a lower coefficient of fricton. Now if they could come up with some kind special lubricant that could make CF even more friction resistant, then that just might work!
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  10. #10
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    Quote Originally Posted by motochick View Post
    Coming from a road bike background, steel is real. There are some killer new, strong light alloys out there that I would love to see being used for MTB's. I would love to feel that damping quality of steel on a DH bike. Hydro-formed tubes could be cool, too! JMHO
    I'd love to see more MTN bikes dressed in 853 or 631 chromoly! The weight would be comparable and the durability would be present, as well.
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  11. #11
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    Please vote your conscience!
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  12. #12
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    Quote Originally Posted by MoabiSlim View Post
    I think that the problem with CF stanchions is more related to friction than anything else.

    Metal surfaces have a lower coefficient of fricton. Now if they could come up with some kind special lubricant that could make CF even more friction resistant, then that just might work!
    If the problem is simply that CF coatings are not sufficiently slick, you'd think that a simple solution would be to coat the CF in a thin layer of aluminum; let the CF provide the strength, and the aluminum the rest.

    However, aluminum and CF likely react to temperature extremes differently, so there may be an issue with the bond's durability, or even with the integrity of the entire assembly. It'd also be more expensive, of course...

  13. #13
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    Just my opinion, but feel that we havn't really even seen the whole deal of really looking to extracting stronger lighter tubing. Extracting differing thickness etc etc....

    Carbon will be the typical norm and a change will be that Alu will become like Ti... Call me nuts, but just my opinion..

    Be keen to hear from some whom know heaps about Alu as a frame material....
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  14. #14
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    A big problem I see is the use of 6061 in place of more expensive 7075-t6. 7075 is a memory metal with a higher structural rating than 6061. It's also not as ridged, and when it does bow/bend/stretch it has the memory aspect to return to it's former shape. I've built suspension links that I've watched bend 3-4 inches over a 30" span, spring back perfectly straight on it's own. It's really an amazing material. It's expensive, but it's cheaper than carbon and less fragile than the uber brittle chromolys. 8 series tubing sounds ridiculous! The shear factor would be unreal, you could literally shatter a frame like glass.

  15. #15
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    Quote Originally Posted by action fab View Post
    A big problem I see is the use of 6061 in place of more expensive 7075-t6. 7075 is a memory metal with a higher structural rating than 6061. It's also not as ridged, and when it does bow/bend/stretch it has the memory aspect to return to it's former shape. I've built suspension links that I've watched bend 3-4 inches over a 30" span, spring back perfectly straight on it's own. It's really an amazing material. It's expensive, but it's cheaper than carbon and less fragile than the uber brittle chromolys. 8 series tubing sounds ridiculous! The shear factor would be unreal, you could literally shatter a frame like glass.
    Interesting, thank you for sharing this... It is not a topic I know a lot about, but you illustrate it well with words.... Carbon will be the new main stream alu, and alu will move to a high end product....
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  16. #16
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    I think carbon will become the norm. If cost can be brought under control.. Manufacturers won't be able to keep their sales numbers up with just expensive carbon frames.. If $10,000.00 DH bikes were all that was available the growth of our sport would slow significantly.

  17. #17
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    Okay, let's get some reality in here.

    The Trek Session 9.9 is $8500, not $10,000. It has an amazing build. This is by no means an over the top or even unusual price.

    The Santa Cruz V10 Carbon frame only is $3,300. That's $700 more than the aluminum Demo 8 and $300 more than the Intense M9. Again, a bit expensive, but not exactly over the top or unusual.

    Compared to the M9, the V10 has a 10% price premium.

  18. #18
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    Makes the Demo 8 DAM expensive, much like most things Speci

    Quote Originally Posted by recitio View Post
    Okay, let's get some reality in here.

    The Trek Session 9.9 is $8500, not $10,000. It has an amazing build. This is by no means an over the top or even unusual price.

    The Santa Cruz V10 Carbon frame only is $3,300. That's $700 more than the aluminum Demo 8 and $300 more than the Intense M9. Again, a bit expensive, but not exactly over the top or unusual.

    Compared to the M9, the V10 has a 10% price premium.
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  19. #19
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    Quote Originally Posted by MoabiSlim View Post
    I'd love to see more MTN bikes dressed in 853 or 631 chromoly! The weight would be comparable and the durability would be present, as well.
    Not necessarily. Steel, no matter how fancy, is still 3 times as heavy as alumnium - the only way to make a steel frame light is by making the tubes super thin walled. Which is exactly what they do on the light roadbike steel frames. The 853 tubesets go down to a wall thickness of 0.4mm (less than 0.016"). To put that in perspective, a beer can is a bit over 0.1mm.

    It may be steel, but it is still extremely easy to dent because of this. In fact, if the tube has a reasonably large diameter like a down tube, you could easily knock a dent into it with your bare knuckles.


    Carbon has by far the most potential and will take over most of the market pretty soon. A lot of the high-end models are already on carbon frames, this will trickle down to the mid-range as carbon frames become cheaper to make.
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  20. #20
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    Quote Originally Posted by lelebebbel View Post
    Not necessarily. Steel, no matter how fancy, is still 3 times as heavy as alumnium - the only way to make a steel frame light is by making the tubes super thin walled. Which is exactly what they do on the light roadbike steel frames. The 853 tubesets go down to a wall thickness of 0.4mm (less than 0.016"). To put that in perspective, a beer can is a bit over 0.1mm.

    It may be steel, but it is still extremely easy to dent because of this. In fact, if the tube has a reasonably large diameter like a down tube, you could easily knock a dent into it with your bare knuckles.


    Carbon has by far the most potential and will take over most of the market pretty soon. A lot of the high-end models are already on carbon frames, this will trickle down to the mid-range as carbon frames become cheaper to make.

    You're not going to dent 853 chromoly, you will crack it like an eggshell.

  21. #21
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    I like 4130 cro-moly and 6061 aluminum...

  22. #22
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    Sometimes the way the material is applied is just as important if not more important than the material itself...

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    New question here.

    Quote Originally Posted by nikos7 View Post
    I like 4130 cro-moly and 6061 aluminum...
    Both, 4340 and 7075 are far superior frame materials.

  24. #24
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    Quote Originally Posted by action fab View Post
    You're not going to dent 853 chromoly, you will crack it like an eggshell.
    853 chromoy steel is quite a bit stronger than 4130 steel. Steel has a much higher yield capacity than aluminum. Aluminum therefore, will tend to crack long before any kind of steel. Steel bends before breaking, aluminum does not.
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    Quote Originally Posted by nikos7 View Post
    Sometimes the way the material is applied is just as important if not more important than the material itself...

    Yes! Construction and design are always critical factors...
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  26. #26
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    Quote Originally Posted by lelebebbel View Post
    Not necessarily. Steel, no matter how fancy, is still 3 times as heavy as alumnium - the only way to make a steel frame light is by making the tubes super thin walled. Which is exactly what they do on the light roadbike steel frames. The 853 tubesets go down to a wall thickness of 0.4mm (less than 0.016"). To put that in perspective, a beer can is a bit over 0.1mm.

    It may be steel, but it is still extremely easy to dent because of this. In fact, if the tube has a reasonably large diameter like a down tube, you could easily knock a dent into it with your bare knuckles.


    Carbon has by far the most potential and will take over most of the market pretty soon. A lot of the high-end models are already on carbon frames, this will trickle down to the mid-range as carbon frames become cheaper to make.
    The only advantage in using 853 or 631 chromoly steel, is the fact that these steel alloys can be double-butted and made lighter. However, the actual steel itself doesn't have to be double-butted. It would still remain just as heavy as 4130 chromoly steel, but it would be quite a bit stronger.

    No modern day chromoly steel MTB bike is twice the weight of its aluminum counterpart. It might be as much as five pounds more, but that's about it!
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  27. #27
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    I've beat the sh!t out of my V10, and it is just so freakin solid! Why buy an aluminum when you can spend 10% or less more and get a lighter, stronger, carbon bike?

    Everything is dependent on the carbon layup and quality. It is very hands on intensive. You need to ensure the environment is clean, the layup doesn't have air bubbles in it, and the right material is used in the right location. FEM (Finite Element Software) is very helpful with this.

    Many feel that Carbon is weak. It can be if not constructed properly. It also has a softer feel than aluminum and Steel (that's because it is). You can scratch the polymer with your fingernail, doesn't mean it isn't strong, just not as hard.

    I've crashed my V10 into several rocks, trees, lift things, car things, etc, but it is still stronger than AL and a lot stiffer.
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  28. #28
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    Quote Originally Posted by MoabiSlim View Post
    The only advantage in using 853 or 631 chromoly steel, is the fact that these steel alloys can be double-butted and made lighter. However, the actual steel itself doesn't have to be double-butted. It would still remain just as heavy as 4130 chromoly steel, but it would be quite a bit stronger.

    No modern day chromoly steel MTB bike is twice the weight of its aluminum counterpart. It might be as much as five pounds more, but that's about it!
    Aluminium tubes can also be double butted, in fact most lightweight aluminium frames are made out of double butted tubes. This simply means that the tube has thinner walls in the center compared to the ends where the welds are, it's nothing special and not some sort of a property of steel.

    My point is that steel, as a material, is 3 times as heavy as aluminium, so to make a lightweight steel frame, you have to use less steel. In other words, you have to make the tubes thinner, which leads to tubes that dent very easily.
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  29. #29
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    Quote Originally Posted by lelebebbel View Post
    Aluminium tubes can also be double butted, in fact most lightweight aluminium frames are made out of double butted tubes. This simply means that the tube has thinner walls in the center compared to the ends where the welds are, it's nothing special and not some sort of a property of steel.

    My point is that steel, as a material, is 3 times as heavy as aluminium, so to make a lightweight steel frame, you have to use less steel. In other words, you have to make the tubes thinner, which leads to tubes that dent very easily.
    Much of this concept you've got right. However, the reason that aluminum tubes have been made wider and thicker is due to aluminum's inherent weakness when compared to steel. Therefore, practically three times as much aluminum has to be used in order to account for the extra width and thickness of most aluminum frames.

    The part about steel denting easily. You must be absolutely kidding me! Even the double butted 853 chromoly steel doesn't dent as easily as aluminum. That's only because, it's steel. Steel by nature is tough and durable. It doesn't have to be widened or thickened to make up for any frailties.
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  30. #30
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    Quote Originally Posted by IndecentExposure View Post
    I've beat the sh!t out of my V10, and it is just so freakin solid! Why buy an aluminum when you can spend 10% or less more and get a lighter, stronger, carbon bike?

    Everything is dependent on the carbon layup and quality. It is very hands on intensive. You need to ensure the environment is clean, the layup doesn't have air bubbles in it, and the right material is used in the right location. FEM (Finite Element Software) is very helpful with this.

    Many feel that Carbon is weak. It can be if not constructed properly. It also has a softer feel than aluminum and Steel (that's because it is). You can scratch the polymer with your fingernail, doesn't mean it isn't strong, just not as hard.

    I've crashed my V10 into several rocks, trees, lift things, car things, etc, but it is still stronger than AL and a lot stiffer.
    I agree with everything you've stated here, except for one thing....The V-10 is not 100% CF!
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  31. #31
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    Quote Originally Posted by MoabiSlim View Post
    Much of this concept you've got right. However, the reason that aluminum tubes have been made wider and thicker is due to aluminum's inherent weakness when compared to steel. Therefore, practically three times as much aluminum has to be used in order to account for the extra width and thickness of most aluminum frames.

    The part about steel denting easily. You must be absolutely kidding me! Even the double butted 853 chromoly steel doesn't dent as easily as aluminum. That's only because, it's steel. Steel by nature is tough and durable. It doesn't have to be widened or thickened to make up for any frailties.

    Again. Yes, OBVIOUSLY aluminium is weaker than steel, thanks for pointing that out. Steel is actually about 3 times as stiff as aluminium, while also being 3 times as heavy.

    Great that I am getting the concept right, I knew all this mechanical engineering school was good for something.

    .....

    I'll try again:

    If you make a tube out of steel that is supposed to be light, you have to make it smaller, or with thinner steel than a comparable aluminium tube. Tube stiffness depends on tube diameter and wall thickness, but wall thickness is pretty much directly 1:1 proportional to stiffness, while diameter factors in to the power of 3. Weight, of course, depends solely on the amount of material used, and is thus directly proportional to both diameter and wall thickness.

    In other words, make a tube with twice the diameter, and it will be roughly 8 times as stiff, but only twice as heavy, given the same wall thickness and material. Then reduce the wall thickness by half, now the tube is still 4 times as stiff as the original tube, but the same weight.
    If you make the tube out of a material that is 3 times as heavy but 3 times as strong, you have to reduce wall thickness to 1/3 of the original or you end up with a heavier tube. A steel tube with the same stiffness, weight and diameter as a aluminium tube will have only 1/3 of the wall thickness!

    That is why the 853 tubes have a ridiculously thin wall thickness of 0.4mm in the middle, while a typical aluminium frame wouldn't go below 1-1.5mm.
    There is a limit as to how thin you can make tubes - first, they become harder to manufacture, second, they become increasingly prone to dents the thinner they get DESPITE being made out of a stronger material, until you end up with a coke can.

    And that exactly is why a steel tube of the same weight and stiffness as a aluminium tube will be ridiculously thin walled and thus MORE likely to dent.


    You can also read this if you don't believe me:
    Peloton
    Diameter: A tube’s diameter will vary according to its placement in the frame. The tubes that make up the front half of the bicycle are the largest in diameter. The tubes in the rear half of the bicycle are much smaller in diameter and taper in size as they approach the rear wheel. As a tube increases in diameter or in wall thickness, its stiffness increases. Increasing a tube’s wall thickness increases its stiffness at a roughly 1:1 ratio with its weight. Increasing a tube’s diameter, however, increases its stiffness at a cubed rate. If you double the diameter of a given tube, the new tube will weigh twice as much but be eight times as stiff as the smaller tube. This is why thin-walled, large-diameter tubing is so popular; it is possible to create an aluminum tube that is both stronger and lighter than those made from steel. As diameter goes up and thickness goes down, the ability to resist dents goes down—so there is a limit to the diameter/thickness ratio.

    There are a few other issues with these super thin steel tubesets as well. Firstly, they are expensive because it is very hard to make tubes that thin walled. Second, it is really difficult to build a frame with them because it isn't exactly easy to weld something that thin. This becomes even more difficult when building a full suspension frame because unlike a Roadbike or Hardtail, you need dozens of tubes and every tube has to have a different length, making it harder to make double butted tubes. So now you have to use thick-walled, non butted tubes whenever a short tube is required - just so you can still weld the thing. Which obviously makes it heavier.
    Last edited by lelebebbel; 08-21-2012 at 03:22 AM.
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  32. #32
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    Quote Originally Posted by MoabiSlim View Post
    Solely based upon your personal experience and the experiences of close friends and associates, which frame material would you say best suits DH MTN biking:

    1) Carbon

    2) Aluminum

    3) Chromoly Steel

    4) Carbon/Aluminum Combo

    Also:

    What's your confidence level concerning carbon?

    On a scale from 1 to 5, how to you feel about the suspected quirkyness of carbon.

    * Give it a 1 for the absolute quirkiest and 5 for NOT quirky at all.

    1 - It's Extremely Quirky and everbody should know that by now!

    3 - Your still on the quirky fence (you still have your doubts).....

    5 - It's not quirky at all and stop questioning its integrity, dammit!

    Well, you know my stand on this matter, so just for the rest of the people reading this thread: a clean 5!

    Magura

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    Quote Originally Posted by MoabiSlim View Post
    I don't know how long it will take. Perhaps a year. Perhaps 10 years. I'm not sure. What I do know for certain, is that the time is most definitely coming. I feel that we're so darned close!
    Hmm, last year maybe


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    I could be wrong, but labor has got to be the largest factor contributing to the manufacturing costs of a bike frame. With that in mind, carbon seems like it has the greatest potential for improvement in efficiencies.

    It doesn't seem that long ago (mid 80's) that aluminum seemed like an exotic material.

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    Quote Originally Posted by lelebebbel View Post
    .....

    I'll try again:

    If you make a tube out of steel that is supposed to be light, you have to make it smaller, or with thinner steel than a comparable aluminium tube. Tube stiffness depends on tube diameter and wall thickness, but wall thickness is pretty much directly 1:1 proportional to stiffness, while diameter factors in to the power of 3. Weight, of course, depends solely on the amount of material used, and is thus directly proportional to both diameter and wall thickness.

    In other words, make a tube with twice the diameter, and it will be roughly 8 times as stiff, but only twice as heavy, given the same wall thickness and material. Then reduce the wall thickness by half, now the tube is still 4 times as stiff as the original tube, but the same weight.
    If you make the tube out of a material that is 3 times as heavy but 3 times as strong, you have to reduce wall thickness to 1/3 of the original or you end up with a heavier tube. A steel tube with the same stiffness, weight and diameter as a aluminium tube will have only 1/3 of the wall thickness!

    That is why the 853 tubes have a ridiculously thin wall thickness of 0.4mm in the middle, while a typical aluminium frame wouldn't go below 1-1.5mm.
    There is a limit as to how thin you can make tubes - first, they become harder to manufacture, second, they become increasingly prone to dents the thinner they get DESPITE being made out of a stronger material, until you end up with a coke can.

    And that exactly is why a steel tube of the same weight and stiffness as a aluminium tube will be ridiculously thin walled and thus MORE likely to dent.


    You can also read this if you don't believe me:
    Peloton



    There are a few other issues with these super thin steel tubesets as well. Firstly, they are expensive because it is very hard to make tubes that thin walled. Second, it is really difficult to build a frame with them because it isn't exactly easy to weld something that thin. This becomes even more difficult when building a full suspension frame because unlike a Roadbike or Hardtail, you need dozens of tubes and every tube has to have a different length, making it harder to make double butted tubes. So now you have to use thick-walled, non butted tubes whenever a short tube is required - just so you can still weld the thing. Which obviously makes it heavier.
    Hi there Lelebebbel!

    I think that to some extent, we're comparing apples to oranges Since steel and aluminum are both different frame materials, they have different densities, melting points, tensile strengths, yield capacities, etc...

    In order to make aluminum tubes suitable for cycling, they have to be strengthened. That's accomplished by constructing their tubing both wider and with thicker walls, than their steel counterparts.

    4130 chromoly steel is very strong, has a high yield capacity, and is quite dent resistant.
    853 chromoly, though made with thinner walls, has an even greater yield capacity and is even more dent resistant.

    I think that for us to actually prove one way or the other, about the actual degree of dent-resistance, we would need a empirical evidence. Otherwise, it's all just speculation, because one of the primary properties of 853 chromoly steel, is dent resistance, due to its extra toughness derived from the way that it's treated with heat during its formation.

    I didn't intend to subtract anything from your obvious intelligent persona. It's just that this subject matter is really interesting to me!
    Last edited by MoabiSlim; 08-21-2012 at 02:50 PM.
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    Quote Originally Posted by Mr.Magura View Post
    Well, you know my stand on this matter, so just for the rest of the people reading this thread: a clean 5!

    Magura
    You appear to be just a tad too enthusiastic for your reponse to be valid.

    Sure you don't have any latent invest in your answer?
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    Quote Originally Posted by MoabiSlim View Post
    You appear to be just a tad too enthusiastic for your reponse to be valid.

    Sure you don't have any latent invest in your answer?
    Naah, just got tired somewhere along the way, of treating metal frames like an egg



    Magura

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    titanium. fosho.
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    Quote Originally Posted by MoabiSlim View Post
    Hi there Lelebebbel!

    I think that to some extent, we're comparing apples to oranges Since steel and aluminum are both different frame materials, they have different densities, melting points, tensile strengths, yield capacities, etc...

    In order to make aluminum tubes suitable for cycling, they have to be strengthened. That's accomplished by constructing their tubing both wider and with thicker walls, than their steel counterparts.

    4130 chromoly steel is very strong, has a high yield capacity, and is quite dent resistant.
    853 chromoly, though made with thinner walls, has an even greater yield capacity and is even more dent resistant.

    I think that for us to actually prove one way or the other, about the actual degree of dent-resistance, we would need a empirical evidence. Otherwise, it's all just speculation, because one of the primary properties of 853 chromoly steel, is dent resistance, due to its extra toughness derived from the way that it's treated with heat during its formation.

    I didn't intend to subtract anything from your obvious intelligent persona. It's just that this subject matter is really interesting to me!

    The point is that despite the higher yield strength of steel, the dent resistance is still less because of the reduced wall thickness. As anything to do with metal, this is a fairly well-studied subject because the auto industry deals with the same problems. No speculation required, and plenty of empirical evidence is available. Here is a short paper that explains it:
    http://www.wseas.us/e-library/transa...07/30-304N.pdf

    This is the important bit:
    Y utori [3] suggested experimental follows:
    equation
    as
    a
    F[0]=K[1] * σ[Y] * t^a
    where F[0] is the denting force require for 0.1 mm
    dent depth, K[1] is material constant, σ[Y] is yielding
    strength, t is the sheet thickness and a is geometric constant.
    Note that it is sheet thickness to the power of a
    (The paper is about testing this equation and comparing it with a real world dent test, as the tables show the equation is pretty accurate)
    Consider that if automotive exterior panel thickness decreases to reduce vehicle weight, then panel dent resistance decrease by the power of 2 or more.
    ... which means basically, half as thick = at best 1/4 as dent resistant. Even with the higher yield strength of a high-end steel like the type used for 853 tubing, the ^2 factor will always dominate once the tube becomes very thin, no matter how strong the material itself is.
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    Quote Originally Posted by MoabiSlim View Post
    Hi there Lelebebbel!

    I think that to some extent, we're comparing apples to oranges Since steel and aluminum are both different frame materials, they have different densities, melting points, tensile strengths, yield capacities, etc...

    In order to make aluminum tubes suitable for cycling, they have to be strengthened. That's accomplished by constructing their tubing both wider and with thicker walls, than their steel counterparts.

    4130 chromoly steel is very strong, has a high yield capacity, and is quite dent resistant.
    853 chromoly, though made with thinner walls, has an even greater yield capacity and is even more dent resistant.

    I think that for us to actually prove one way or the other, about the actual degree of dent-resistance, we would need a empirical evidence. Otherwise, it's all just speculation, because one of the primary properties of 853 chromoly steel, is dent resistance, due to its extra toughness derived from the way that it's treated with heat during its formation.

    I didn't intend to subtract anything from your obvious intelligent persona. It's just that this subject matter is really interesting to me!
    Moabi, with all due respect, you gotta look at bit closer at the math presented to you.
    We had the same issue last time you brought up the topic of materials.

    There is plenty of engineering done in this field (be that material science), most of it regarding composites is from the aviation and/or military.
    That the paper does not specific state "bicycle frame test", does not render the test or engineering invalid, perhaps even the contrary, as some of this is over the budgets of most bike manufacturers.
    What lelebebbel just presented, needs no testing or what not, as it is basic engineering.
    If he is wrong, a lot of things in this world are going to fail real soon

    Magura

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    Quote Originally Posted by lelebebbel View Post
    The point is that despite the higher yield strength of steel, the dent resistance is still less because of the reduced wall thickness. As anything to do with metal, this is a fairly well-studied subject because the auto industry deals with the same problems. No speculation required, and plenty of empirical evidence is available. Here is a short paper that explains it:
    http://www.wseas.us/e-library/transa...07/30-304N.pdf

    This is the important bit:


    Note that it is sheet thickness to the power of a
    (The paper is about testing this equation and comparing it with a real world dent test, as the tables show the equation is pretty accurate)


    ... which means basically, half as thick = at best 1/4 as dent resistant. Even with the higher yield strength of a high-end steel like the type used for 853 tubing, the ^2 factor will always dominate once the tube becomes very thin, no matter how strong the material itself is.
    So what have you proven? That dent resistance is frame material thickness dependent. Of course, we already know that! However, it's also frame material dependent. Some frame materials are just going to be more resistant to denting than others. Chromoly 853 is just naturally more dent resistant than either aluminum or 4130 chromoly.

    It's most definitely more dent resistant than aluminum! That's my hypothesis. Now, mathematics is a tool used to either prove or disprove a hypothesis within the parameters of an experiment. What we need is an empircal example, upon which are mathematics can be used in order to properly assess generated data, so that we can perform a comparative study. Has anyone done that?

    We need to know the exact values of the variables, so that we can actually observe how the domain varies with the range.. We need to see how t varies within the dent function, given the different frame constants.

    The simple formula is inadequate.

    Quote Originally Posted by Mr.Magura View Post
    Moabi, with all due respect, you gotta look at bit closer at the math presented to you.
    We had the same issue last time you brought up the topic of materials.

    There is plenty of engineering done in this field (be that material science), most of it regarding composites is from the aviation and/or military.
    That the paper does not specific state "bicycle frame test", does not render the test or engineering invalid, perhaps even the contrary, as some of this is over the budgets of most bike manufacturers.
    What lelebebbel just presented, needs no testing or what not, as it is basic engineering.
    If he is wrong, a lot of things in this world are going to fail real soon

    Magura
    Time is relative Mr. Magua...

    Currently, this rock is falling into the sun. The economy is falling. Perhaps my confidence level is slowly falling too!
    Last edited by MoabiSlim; 08-22-2012 at 09:09 AM.
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    Quote Originally Posted by MoabiSlim View Post
    So what have you proven? That dent resistance is frame material thickness dependent. Of course, we already know that! However, it's also frame material dependent. Some frame materials are just going to be more resistant to denting than others. Chromoly 853 is just naturally more dent resistant than either aluminum or 4130 chromoly.

    It's most definitely more dent resistant than aluminum! That's my hypothesis. Now, mathematics is a tool used to either prove or disprove a hypothesis within the parameters of an experiment. What we need is an empircal example, upon which are mathematics can be used in order to properly assess generated data, so that we can perform a comparative study. Has anyone done that?

    We need to know the exact values of the variables, so that we can actually observe how the domain varies with the range.. We need to see how t varies within the dent function, given the different frame constants.

    The simple formula is inadequate.
    The values of the variables are readily accessible, if you feel like making it a piece of math withing very small tolerances.
    Fact remains though, that rough estimations shows no need to get into the smaller details, at the outcome is obvious and beyond any doubt.

    To quote Lellebbel :

    ... which means basically, half as thick = at best 1/4 as dent resistant. Even with the higher yield strength of a high-end steel like the type used for 853 tubing, the ^2 factor will always dominate once the tube becomes very thin, no matter how strong the material itself is.

    End quote.

    That simple formula, is more than adequate.
    It proves exactly that, in an easily understandable way to boot


    Moabi, that you like to ponder material properties is nice, but to refuse all basic engineering in the process, is not bringing you anywhere.

    The experiments you seem to not understand the existence of, is called material data.
    Datasheets of any material, is based on tests, hence you can apply those factors already known from the datasheet, ad a bit of math, and have a very close to reality result.
    I know your next dispute will be the "very close" part, but let me tell you, it is within factors so small, that they are with no interest regarding the topic at hand.


    Magura

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    Quote Originally Posted by MoabiSlim View Post


    Time is relative Mr. Magua...

    Currently, this rock is falling into the sun. The economy is falling. Perhaps my confidence level is slowly falling too!
    In this case, if you truly believe that proven basic engineering is that far off the mark, I'd stay clear of anything like bridges, houses, planes, cars, you name it.

    Just about anything is going to fail within minutes, if you are right.


    Magura

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    I won't be happy until I can get a DH frame made of cast iron.

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  45. #45
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    Quote Originally Posted by Mr.Magura View Post
    The values of the variables are readily accessible, if you feel like making it a piece of math withing very small tolerances.
    Fact remains though, that rough estimations shows no need to get into the smaller details, at the outcome is obvious and beyond any doubt.

    To quote Lellebbel :

    ... which means basically, half as thick = at best 1/4 as dent resistant. Even with the higher yield strength of a high-end steel like the type used for 853 tubing, the ^2 factor will always dominate once the tube becomes very thin, no matter how strong the material itself is.

    End quote.

    That simple formula, is more than adequate.
    It proves exactly that, in an easily understandable way to boot


    Moabi, that you like to ponder material properties is nice, but to refuse all basic engineering in the process, is not bringing you anywhere.

    The experiments you seem to not understand the existence of, is called material data.
    Datasheets of any material, is based on tests, hence you can apply those factors already known from the datasheet, ad a bit of math, and have a very close to reality result.
    I know your next dispute will be the "very close" part, but let me tell you, it is within factors so small, that they are with no interest regarding the topic at hand.


    Magura
    Mr. Magura!

    That same formula goes for all frame materials. It does not stand alone. It begs for comparative data variables...

    C'mon now!
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  46. #46
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    Quote Originally Posted by MoabiSlim View Post
    Mr. Magura!

    That same formula goes for all frame materials. It does not stand alone. It begs for comparative data variables...

    C'mon now!
    And that is exactly the point

    Pick any material, and fill in the different properties into the formula, and you will find that no material commonly used for bikes, does not adhere to what you have been told by lellebbel.
    EDIT: well, no metal does not adhere to that formula. Composites are a bit harder to generalize in this regard.


    Magura

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    Quote Originally Posted by MoabiSlim View Post
    So what have you proven?
    I think I have just proven that you will ignore everything, and consider only your "feelings" regarding the material as relevant, despite clear and definitive evidence to the contrary. As Mr. Magura has pointed out, the equation provided above is valid for all metals, it contains a variable for tensile strength, and another material constant.

    Look, since you are clearly interested in this subject, may I suggest you take up an engineering course at a university. It can be quite eye opening. The very first thing you will learn though is that personal beliefs, old wives tales and hear-say don't lead to accurate results and have no place in science.
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  48. #48
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    The only real downside of carbon these days is cost. Durability if far better than alloy. Obviously weight and rigidity are as well.
    Overall, go carbon if its coming from the right manufacturer. (ie the V10 with an Enve rear end).
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    I have to say I feel like I read the exact same thread with the same participants a year ago hah.

    Its all moot though, clearly the future is wood

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    well if we're going there...


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