Steel is better?

Discussion in 'The Bike Cafe' started by tingle_wayne, Nov 17, 2005.

  1. tingle_wayne

    tingle_wayne New Member

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    My Bianchi is steel frame, but i'm still too new to tell the difference in the feel. Why do other people like steel so much? (i love my new bike)
     
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  2. insideout

    insideout New Member

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    I believe it is because steel has a bit more flex to it, many people complain that the ride of aluminium can be harsh. This is probably more noticable in mountain bikes. I rode an aluminium hardtail for 6 years and have been riding a steel hardtail for the last 4 years. While the frame geometries are a little different, I still think steel has a better feel to the ride....................peace:)
     
  3. wheelist

    wheelist New Member

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    Because it gives.

    Because it'll last a lifetime (if you ride nicely).

    Because you can get it repaired if it breaks, no matter where in the world you are.

    Because it sounds nice when you flick it.

    Steel. More precious to me than gold. :)
     
  4. dabac

    dabac Well-Known Member

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    That's a design feature, and not solely due to material properties. It can be achieved in any material.

    Another design feature. If you want a frame that can take "unlimited" mileage you can have it in any material, as long as the design is adapted accordingly.

    Yeah, right. The odds of getting it repaired are better, but thin wall Cr-Mo tubing is not not the most forgiving material to work by a long shot. It's far easier making a mess of things rather than getting it right.
     
  5. wheelist

    wheelist New Member

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    The modulus of elasticity of aluminium (whatever grade) is only about 1/3 that of steel. Whilst 'give' can be designed in, it's a natural occurrence in steel (as compared with aluminium). If it can be achieved in any material then why aren't frames made out of cheese?

    Again, aluminium frames simply won't last as long as steel. A few short seasons of hard racing and you'll need a new one. Not with steel. (I'm talking MTBs here of course)

    And again. Compare it to the alternatives.

    p.s. you didn't criticise the comment about the sound of steel? Ping. Ping.
     
  6. Verewolf

    Verewolf New Member

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    Have to agree with Wheelist.
    I thought about getting a new mtb.
    Looked at bikes with: steel, titanium, kinesium, scandium, and aluminum.
    But when all is said and done you can't beat a good steel bike.
    And the price is right for steel bikes.
    It may weight more than other materials but the difference in weight isn't that important to me.
    Now I'm down to deciding what is the best steel i.e. Columbus steel, Origin etc.
     
  7. chrisPDX

    chrisPDX New Member

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    Not true. The fatigue strength of steel (like any other material) will decrease with time under cyclic loading. Unlike aluminum, however, the decrease in steel’s strength will begin to taper off after a certain number of cycles. This occurs at the endurance limit of the material (usually expressed as a percent of ultimate strength). As long as the frame is designed such that it doesn’t encounter any loads above the endurance limit, then it will have infinite life. Aluminum, on the other hand, continues to decrease in strength until it eventually fails. In other words, given enough loading cycles, anything made from aluminum will fail (regardless of the design, this is a material issue). For a bicycle frame, a safe bet would be to replace an aluminum frame every 5 years (your mileage will vary). The same isn’t true for a properly designed and maintained steel (or titanium) frame which will last virtually forever.

    BTW, this isn't an anti-aluminum post (my current ride is Al after all). I'm simply pointing out that there are some inherent differences in frame materials, especially in regards to lifespan. Stiffness, on the other hand, is largely a function of design, as mentioned previously.
     
  8. huhenio

    huhenio New Member

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    Price!

    It is also a matter of riding style and personal preference.

    Flexy light, expensive= carbon
    Stiff, light, and moderate = alu
    Somewhere in between, affordable = steel

    In general ... there are particular cases though:)
     
  9. Ausmith

    Ausmith New Member

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    Why Steel is Real.

    Objective
    1) Up until the last decade steel was really the only affordable way to have a custom bike built. For many a custom may not be necessary, but if you are one of those folks who doesn't fit well on a "shelf" geometry custom frames are a blessing.

    2) Repairability. This really applies more to lugged frames, but if you race a lot your chances of hitting the pavement at speed increase 10-fold and of course your equipment can get messed up when it is sliding across the asphalt or being run over by other riders. There is nothing worse than being a broke bike racer, out of town, with a tweaked or broken frame. Steel at least give you the opportunity to coldset the rear end, derailleur hanger, or in some cases have a tube or two replaced. There are still plenty of excellent craftsman who know how to repair a steel bike without messing it up.

    3) Ride quality. I know some folks might jump on me for putting ride quality under the "Objective" heading. Before you do that, let us all just agree that steel offers a "different" ride quality as compared to the other materials which also offer their own unique qualities. See, if you put it in those terms you can be objective... as for the actualy quality of the ride, now we are getting subjective. I've ridden a both custom steel bike and a rigid aluminum bike in my career. I've logged more miles on steel bikes, but at least 10,000miles on the aluminum so I think I can make a valid comparison. What I can say for certain is that the aluminum bike is stiffer and lighter, but it also caused me more lower back fatigue in long races and training rides. One year, about mid season, my aluminum team bike (I won't mention the name but I think it started with the letter "C") broke. Well I should say it cracked at the junction of the seat and chain stay on the drive side. I didn't have a spare bike and it was going to take some weeks to get a replacement. My only choice was to change bikes mid-season back one of my own steel - God I never want to do that again, changing bikes mid season is a real PITA. The geometry was very close to being the same and I swapped all of the components over, so in a sense the only thing that changed was the frame. After the first race back on the steel bike, I had 0 lower back fatigue - actually it was my second race on that bike, but they were both in the same day! I think it was 150k total that day of criterium racing.

    4) Steel is usually the cheapest. However, I bet if you look at actual manufacturing costs aluminum comes in a close second or maybe even cheaper. I think a lot of the big companies will take less margin in exchange for the opportunity to market another low-to-moderate range of bikes in their offering.


    Subjective
    1) Retro Weinie Factor. Steel frames have been around as long as the bicycle itself (go figure, actaully I'm not sure if the first frame was steel or not). Like many other material items with a rich history (vintage cars is another that comes to mind) there exists a sub culture of folks who are intrigued by the novelty of owning and using old technology. I must admit it is neat to think you can race on a frame that is built on 50 year old technology and still be somewhat competitive at the top level - where the other guys are out there on their super triple winged carbon/ti compact space fighter bikes.

    2) Craftsmanship. Becuase it is older technology the construction method can, depending on who is building the steel frame, fall into the category of a craft. Selecting the tubes, drawing the print, mitering the tubes, brazing, and finishing - all done by hand. There is some charm and appeal to own a frame that is crafted.

    I'm spent. I need to go work on my car.
     
  10. artmichalek

    artmichalek New Member

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    I think you need to re-read that chapter in your text book. You've got that a bit backwards. Besides, doing a fatigue analysis on an actual bike frame is so horribly complex that any maufacturer that claims they did one either lied of half assed it.

    Exactly. As lugged steel construction has shifted from the industry standard to a specialty market this is becoming more evident. I have no doubt that some of the steel frames being made today are the finest that have ever been built. Now if only I could afford one...
     
  11. chrisPDX

    chrisPDX New Member

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    From Fundamentals of Machine Component Design 3rd ed., by R. Juvinall & K. Marshek:

    p. 306 “Numerous tests have established that ferrous materials have an endurance limit, defined as the highest level of alternating stress that can be withstood indefinitely without failure… It is customary to make the conservative assumption that ferrous materials must not be stressed above the endurance limit if a life of 10^6 or more cycles is required.”



    p. 308 “Representative S-N curves for various aluminum alloys are shown… Note the absence of a sharply defined “knee” and a true endurance limit. This is typical of nonferrous metals.”



    p. 309 “Titanium and its alloys behave like steel in that they tend to exhibit a true endurance limit in the range of 10^6 to 10^7 cycles…”



    I could have been a bit more precise in the terminology of my last post, but I did it from memory. Since I am a bit confused, please tell me specifically how the above quotes contradict what I originally said instead of just talking down to me.



    I’m not sure if this type of analysis is typically performed or not, but I don’t see what it has to do with what I said about the material properties of steel vs. aluminum. A fatigue test on a bike frame could be performed, however, which is probably more reliable due to the variability of frame materials, weld quality, etc. Just because your school may not have the facilities to do this, don’t assume it isn’t being performed in industry.
     
  12. Fizzy23

    Fizzy23 New Member

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    Yes I agree, steel good!!!
     
  13. artmichalek

    artmichalek New Member

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    You said that the fatigue strength of steel goes down with time under cyclic loading, which doesn't make any sense. The strength of the material does not taper off as you load it cyclically. The number of cycles to failure decreases with stress amplitude. There's a difference.


    It has everything to do with the discussion. A block of metal is not a bike frame and vice versa. A reliable fatigue test on a bike frame would require a manufacturer to break 20-30 frames. If you have proof that a manufacturer is doing that I'd like to see it. The reason for not doing such a test has nothing to do with the facilities you think I may or may not have access to. It has to do with the fact that the data would be useless. You simply can't duplicate the stress history experienced by a frame in any kind of lab environment. The only thing that test would be good for is developing a fatigue strength of one frame relative to another that was tested under the same conditions.
     
  14. chrisPDX

    chrisPDX New Member

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    Fatigue strength is defined, again by Juvinall & Marshek on p. 304, as: “the intensity of reversed stress causing failure after a given number of cycles corresponding to that number of loading cycles.” So, yes, the fatigue strength does indeed decrease as stress intensity is increased. I never claimed that the ultimate strength or yield strength decreases under cyclic loading. I should have been more specific that the stress intensity is varied to arrive at the endurance limit, but I was trying to avoid being too verbose. We are splitting hairs (and boring all of the non-engineers here) since my main point was simply that steel exhibits and endurance limit while aluminum does not.

    No, you cannot duplicate the exact loading that the frame will experience, but you can make a good guess about it, run an appropriate test with a large enough sample of frames and see what stress levels cause fracture. If it is a steel frame, you will eventually find its endurance limit. If the corresponding stress at the endurance limit is much larger than what you expect the frame to see in service, then you can feel fairly confident that it should last a lifetime. Of course the test can’t predict everything, but that doesn’t make it useless. Consider an automobile crash test, no one can claim that an actual crash will occur in the exact same way (and the probability is very high that it won’t), but conclusions can still be made from the test data (e.g. insurance rates, recommendations from consumer groups, etc).

    The point of my original post was that if, by luck or skill, a steel frame is designed such that it never experiences loads above its endurance limit, then it should last virtually forever. The same cannot be said of an aluminum frame since it has no endurance limit and will eventually fail. If you or I or Trek can’t perform the analysis it still doesn’t change the fact that steel has an endurance limit and aluminum doesn’t.
     
  15. artmichalek

    artmichalek New Member

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    You're starting to get it, but your approach is still a bit backwards. You don't design a frame and then trash a bunch of them to see if you were right. Bike companies are run by accountants, not engineers. The way a fatigue estimate is typically carried out is that you run a stress analysis (typically FEA these days) of the frame for a series of extreme load cases, then make an estimate of the number of cycles it will survive under those stress amplitudes. If the material has an endurance limit, it's ignored. The reason being that most frame manufacturers don't warrant against fatigue in the first place. They have absolutely no financial interest in knowing what the endurance limit of their frame might be.

    An experimental frame fatigue test has been done independently of any manufacturers, but with only one frame for each sample group which makes it a very rough approximation:

    http://www.sheldonbrown.com/rinard/EFBe/frame_fatigue_test.htm

    Like the auto crash test you cited, something like this will only give a relative fatigue strength of one frame to another, not give a real world lifespan estimate. Note that the only two frames that didn't break were aluminum. All of the frames made of materials that "don't fatigue" did.

    This is half right, and hinges on the phrase "virtually forever". I have no doubt that most steel frames regularly see stresses above their endurance limit. But you can build a good frame out of either steel or aluminum that the average rider is either going to; a) get bored with, b) crush in a wreck, or c) die of old age long before seeing a fatigue failure.

    A lot of good reasons for riding steel frames have been posted on this thread, but the steel "doesn't fatigue" line is completely unfounded. While steel "may not" fatigue, a frame made out of it eventually will.
     
  16. blue1

    blue1 New Member

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    yes........me to
     
  17. DiabloScott

    DiabloScott New Member

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    In theory there's no difference between theory and reality; in reality there is.

    All fatigue failures begin with an initial crack. Aluminum can develop that initial crack through cyclical loading, but for steel (never stressed beyond the fatigue strength) the crack must come from elsewhere - material flaw, threaded section, trauma, even a kickstand clamp.

    The reality is, steel bikes fail by fatigue all the time and aluminum bikes can be designed for whatever expected life the engineer wants to.
     
  18. 1id10t

    1id10t New Member

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    Hi Tingle...or is it Wayne

    I'm not going to get into the science of steel vs aluminium (or whatever other materials there are). I have two mountain bikes and one road bike. Of the mountain bikes one is steel and the other is aluminium. Although I enjoy riding both of them, I really favour the steel one. It just seems to have a better ride. They're both set up in a very similar way; ie tyres, riser bar height, sweep, width etc, stem length and so forth. I'm not one to get into the debate about the properties of materials but maybe if you could try an aluminium frame to make a comparison then you might determine a preference. Again, I like to use both bikes as there are pros and cons. For example, the steel is a little heavier and I do actually notice this on hills. The same hills, when ridden with my aluminium bike, seems easier. There are a couple on my way home which I virtually ride granny in the steel bike but am using the middle ring on the other bike. This could be that i'm just fatigued on the day, or the wind is up or whatever. Whatever, the case, go for what suits you.
     
  19. Aussie Steve

    Aussie Steve New Member

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    Have two aluminium bikes. Giants, both of them. Don't like the ride quality AT ALL. Hate it. But they were cheap and at the time I bought them, I thought good value.
    Before one group ride, stood next to a Colnago which had very slender tubes...so it was obviously steel.
    I said to the owner, "my one is aluminium, it must be lighter than yours..."
    lifted HIS up and went "oh sh..." it felt so damn light it was scary.
    He didn't have to say "yes, you were saying?..."
    Right then I realised the truth, that if a Giant is like a Hyundai car, then a Colnago is like an Alfa Romeo or better. Bianchi as well.
    If only I could afford a nice light Dedaccia or Reynolds 853 frame...
     
  20. wheelist

    wheelist New Member

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    Good steel. Ahhhh. :)

    This got me thinking - you've all seen the magazine article: "Steel is Real" - a review of 3 beautiful bikes, all made of steel - harking back to "old technologies" and usually stating that the craftsmanship and skills involved create a better product than the modern materials (and their associated modern approach to production).

    But isn't the thing with steel that it's the very familiarity of the stuff that makes it so trustworthy and the beloved material of so many? I mean, we eat with the stuff, drive in the stuff, walk on it, fly in it, most of our bikes are even made of it(!). It's my opinion that it's this familiarity that gives steel its "real" quality.

    Personally, I love steel bikes. I know how they ride. I know how they'll react to the ride. And most importantly, I can ride them hard in the knowledge that they don't tend to fail unpredictably. Unless of course someone puts a tree (car) in the way. Ouch. :D
     
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