Why are so few FS frames made from steel?

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  • Why are so few FS frames made from steel?
  • Premier Icon brassneck
    Subscriber

    Do the words “leverage” and “torsion” mean anything to you? Or maybe the phrase “second moment of area”?

    You’ve just given me a flashback to my first year at uni. Not the good bits either.

    Premier Icon bigblackshed
    Subscriber

    The only reason steel is frowned upon by the large makers is because they invested years of marketing bullshit to convince the buying public that Alu was “better” than “heavy steel”.

    Slightly OT: As an engineer I will never understand why bearing mounts and housings are made of Alu. Alu can be quicker to machine, not always easier, but the part you are trying to protected is made of softer / weaker material than the disposable bearing you place in it.

    wrecker
    Member

    If you’re a mechanical engineer then please let me know what you’ve designed so I can avoid buying it! And if you’re not, then maybe you should stop disagreeing with one because your arguments are totally flawed. Do the words “leverage” and “torsion” mean anything to you? Or maybe the phrase “second moment of area”? Honestly…

    Oooooh big man use big word.
    So the seat tube which is welded either end and exposed for about 300mm and also 35mm in dia is going to flex more than the swingarm is it?

    The only reason steel is frowned upon by the large makers is because they invested years of marketing bullshit to convince the buying public that Alu was “better” than “heavy steel”.

    dogshit.

    Premier Icon cookeaa
    Subscriber

    I think a more interesting question if we are talking in terms of materials most appropriate to the job(s) is why aren’t more FS bikes produced using a greater mixure of materials?

    Again there are some notable exceptions the Rocket obviously, Balfa BB7, a few others but in most cases it seems frames are manufactured exclusively from one material or another (commonly Aluminium or Carbon composites these days), I’m not saying that this is “Wrong” as such but considering the different jobs each member in a frame has to do, coupled with any constraints on the design and the balancing of manufactureability, cost, weight, strength, stiffness and marketability issues I’m suprized we don’t see more widely mixed material designs.

    Nailing your colours exclusively to one material is probably not that wise, as much as I love bikes like the Chromo-8 and Race-link they are relatively blunt tools for an increasingly precise job…

    For example I’d be intersted to see a Steel front/composite rear ‘AM’ type bike and if/what it might deliver in terms of a Ride/weight/cost tradeoff… Discuss…

    geetee1972
    Member

    Come on guys play nice. This is a great thread don’t spoil it.

    Other steel full suss bikes include the Super Co DH bike which is. Dry like the Brooklyn Machine Works Racelink and I think is built by an ex employee of BMW.

    Where you see steel in FS frames they are always low volume niche manufacturers (Cotic, K9, BMW, Super Co). That large manufacturers tend to prototype designs in steel suggests that steel is easier and cheaper to work with which is critical for low volume manufacturers.

    The cotic rocket looks great and i would love to ride one but you really can get away from its weight. It is heavier by about 1lb over equivalent frames. That’s a tricky ‘sell’ to most people especially when it’s not just 1lb heavier than the mean but 1lb heavier than the next heaviest equivalent. My Nic is the same weight as the rocket but it does offer the option of 20% more travel should I set it up that way. I wouldn’t worry about a full build being 30lbs but lots of other people will.

    I like Aracers response though because he seems, like someone else pointed out, to be reflecting the materials science I’ve read in the last.

    Who remembers the cannondale 3.0 frame from the early 90s? That had huge tubes and super thin walls that would dent if you even squinted at them. It didn’t impair their performance (to a degree) but who wants big dents in their frame?

    geetee1972
    Member

    For example I’d be intersted to see a Steel front/composite rear ‘AM’ type bike and if/what it might deliver in terms of a Ride/weight/cost tradeoff… Discuss…

    I know a very talented engineer and equally talented bike rider who has built exactly that as a home made bike. Steel front with high single pivot carbon fibre swing arm and an idler to neutralise chain torque. 150mm travel super low BB slack HA and he rides it faster than anyone else I’ve ever ridden with. It was featured on the Dirt website around September last year.

    It was pretty heavy but it was a prototype and way over built as such. The swing arm on its own was something like one kilo. But he made it in his garden shed.

    Premier Icon Northwind
    Subscriber

    wrecker – Member

    Not heavy? 7.6lbs for a 16″, it’s heavier than that Foes Shaver which everyone was saying was heavy lest week (and the foes has more bounce)

    Actually, it isn’t- both Foes and Cotic claim 7.8lbs for the medium. And the Foes has less rear travel, and is recommended for a 150mm fork with a max of 160mm. Very comparable frames. Pretty much the same as a Covert, both lighter than an SB66

    legend – Member

    Obviously that’ll be a completely un-biased view from a guy who is trying to sell steel bikes

    Yes that’s right, Cotic found themselves with a load of steel frames in the warehouse one day, then made up an explanation for why you should buy them. Or, maybe not.

    Premier Icon cookeaa
    Subscriber

    I know a very talented engineer and equally talented bike rider who has built exactly that as a home made bike. Steel front with high single pivot carbon fibre swing arm and an idler to neutralise chain torque. 150mm travel super low BB slack HA and he rides it faster than anyone else I’ve ever ridden with. It was featured on the Dirt website around September last year.

    It was pretty heavy but it was a prototype and way over built as such. The swing arm on its own was something like one kilo. But he made it in his garden shed.

    I’ve seen it on the dirt site and it got me thinking at the time, I’ll admit is was in the back of my head when I posted above.

    I have a couple of my own home brew ideas I’m working up right now in a not disimilar vein…

    It was the approach I liked, materials/manufacturing methods chosen, based on available resources/expertise, final product looked very good IMO…

    Oh and just to echo geetee1972; this isn’t really the right thread for trying to bitch-slap each other, take it elsewhere please Ladies…

    Premier Icon jameso
    Subscriber

    There can be quite a bit of flex in a seat tube under hard pedalling or cornering loads, part of the twist along a frame that means flexy frames can run wide on corners. But any frame flexes as a system, the forces going through it don’t really change as the design changes, just where they concentrate and how the frame handles it. Beef up the seat tube and the top and down tube and swingarm may flex more. etc. So all parts are important, needs balancing.

    Anyway, my answer to the OP would be that the global brands sell into markets that don’t have the attraction to durable steel products that we do. There’s no reason for them to use steel where it could be an option. It’s more about fashion / styling and low weight. The UK is different/odd/irrational/unique depending on who you talk to. Being different in this market helps you survive against very well resourced companies with larger R+D and marketing depts. It can also result in some pretty cool/interesting bkes.

    Taff
    Member

    theres a downhill bike. k…something I think? (and not knolly, khs, kona)

    Keewee?

    Premier Icon amedias
    Subscriber

    always nice to see the armchair engineers come out to play

    (leaving the real ones actually get on with engineering things 😉 )

    cynic-al
    Member

    Love the “armchair engineer comments”, hark at thee! I’ve heard more guff here from “I’m an engineer” types than those knowledgable about bikes.

    geetee1972 – Member

    Who remembers the cannondale 3.0 frame from the early 90s? That had huge tubes and super thin walls that would dent if you even squinted at them. It didn’t impair their performance (to a degree) but who wants big dents in their frame?

    tubes on high end Principias could be visibly compressed by hand! Rode great tho!

    AM bikes need to be a bit more crash-resistant I guess.

    Pieface
    Member

    Because steel is real and doesn’t need the skill compensation of full sus

    Premier Icon amedias
    Subscriber

    Love the “armchair engineer comments”, hark at thee! I’ve heard more guff here from “I’m an engineer” types than those knowledgable about bikes.

    I’m not an engineer, I just find these threads amusing as it invariably starts with a genuine question and then degenerates in to hearsay, hyperbole, misled-by-marketing comments, and bad science used to justify peoples pre-conceptions.

    legend
    Member

    Yes that’s right, Cotic found themselves with a load of steel frames in the warehouse one day, then made up an explanation for why you should buy them. Or, maybe not.

    Ah ****, I’ve just read an article by Dave Weagle saying that alu and the DW-link are the best for trail bikes. Now I’m confused, or one if them is wrong, or something.

    It’s almost like brands need a USP….

    amedias, Engineers need lunch breaks too you know!

    geetee1972
    Member

    I’ve seen it on the dirt site and it got me thinking at the time, I’ll admit is was in the back of my head when I posted above.

    It is an incredible bike for being made in a garden shed. I was with Adrian and his fiance in Verbier last year (with Bike Verbier of course) so got to see him ride it the whole week. Apart from Adrian being incredibly talented on the bike, it was amazing to see a home made bike perform. He had some problems with the idler set up, as you might expect; there’s a lot of torque going through a relatively small axle and the bearings take a real hammering. But other than that the whole thing was so solid. I think it weighed in around 34lbs with DH tyres so it wasn’t light but but it was light enough.

    Adrian was very keen on the high single pivot saying it made the suspension work really well but obviously you needed the idler to make it also pedal well.

    theendisnigh
    Member

    [/quote]Rubbish! Why would the seat tube need to be stiff on a FS bike!??!?!?[/quote]

    To stop the seat wobbling of course!

    lemonysam
    Member

    theres a downhill bike. k…something I think? (and not knolly, khs, kona)

    You’re thinking of Katipo I suspect.

    http://katipobikes.pinkbike.com/album/Katipo-bikes/

    Premier Icon Northwind
    Subscriber

    legend – Member

    Ah ****, I’ve just read an article by Dave Weagle saying that alu and the DW-link are the best for trail bikes. Now I’m confused, or one if them is wrong, or something.

    Or possibly they’re wanting different characteristics from their bikes? Crazy idea I know. Turns out, some people even like bikes with no suspension at all!

    geetee1972
    Member

    You’re thinking of Katipo I suspect.

    I’ve never heard of or seen that brand before. Interesting looking bike. It’s basically a Sunn Radical and why not? That was clearly an awesome bike and worked really well.

    loum
    Member

    materials science,
    engineering,
    production scale,
    marketing,
    Economics.

    Take your pick, all are relevant to some extent.
    Some more so than others to different parties (producers and customers), but hard to ignore any one of them.
    IMO, the first four combine to make mass production of allu framed bikes more economically viable, so there are more of them. That’s not to say they’re better or worse.

    wrecker
    Member

    Actually, it isn’t- both Foes and Cotic claim 7.8lbs for the medium. And the Foes has less rear travel, and is recommended for a 150mm fork with a max of 160mm.

    Actually, Cotic state that the small is 7.6lbs. The small Foes is 7.4lbs.
    The Cotic has 150mm rear travel, the Foes 5.75″ (146mm). Foes also recommend forks 120 – 160mm.
    Neither are light bikes. But if you want stiff, strong and light; buy carbon.

    lipseal
    Member

    I found this………

    Aluminum vs. Steel: the truth about stiffness
    Apr 09 ’01    Write an essay on this topic.

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    The Bottom Line Flex is good

    You have all heard the hype about aluminum, how it is ligher faster and better than steel. Accept this for what it is hype. Aluminum bikes are only marginally lighter than steel bikes. The lightest production aluminum frame I know of is the Cu92 Giant XTC frame at 3lbs and only a third of a pound lighter than a 3.3lbs Ritchey P-21. Therefore weight should not be a big concern.

    That leaves stiffness. Aluminum frames are supposed to be faster because they are stiff, because they do not flex, so they are therefore more efficient. This rides on an assumption that flex is inherantly inefficient which is not totally correct. Think back to high school physics, you probably did an experiment with a spring and a weight, you put a small amount of energy into the system and it would go for minutes. It was a really flexy and really efficient system. The only reason it would come to a stop is due to material damping, that is throught the energy moving through the material some of it went out as heat. Ineffecieny in flex is due to the materials damping characteristics.

    So how does this translate to bike frames. Materials like steel and titanium have very low material damping characteristics, meaning that relatively littel energy is lost to heat. That makes sense becuse we make almost all of our springs out of steel or titanium. When you are building up a frame out of these materials you are actually building a spring. On the other hand when one builds a frame out of aluminum they are making the stiffest structure possible, imagine an I Beam. So when you think of flex you shoudn’t think of effiency but rather of the ride of a spring vs. an I beam.

    Imagine a trapoline next to a wood table. Put one person on the trapoline and ask them to jump, do the same with the person on the table. The person on the table will spend the same huge amount of energy everytime trying to jump higher whereas the person on the trapoline would jump much much higher whith the same or less energy expenditure. That is because the person on the trapoline has a temporaily store energy and then use it later when it is more needed. The person on the table can’t do this.

    Now forget about the trapoline and get on your bike on some nice twisty singletrack or a sweet road decent. You lean your bike into a corner, carving a nice right hand curve. Now up ahead you see a tight left hand corner coming up. On the aluminum bike you would need to physically lift the front ent up and over to get it to go the other way, however on the steel bike one simply needs to release the spring to have that energy released, boinging the rider into the left hand carve. A faster and less tiring act than the rider on the aluminum frame. Ride a couple of bikes side by side you’ll see that it is immensely more difficult to hande the really stiff frame.

    This concept reiminds me of a saying in the Italian motorcyle industry “If something is too perfect you tire of it quickly” That is often true of aluminum frames, they are too perfect. In order to make the bike go as fast as it is supposed to go the rider must apply energy at the perfect times in the perfect direction. pull on the handlebars a certain way while cranking with a certain amount of power, and having your butt on a certain perfect point on the seat. This is really difficult to do.

    The Moral of the Story FLEX IS GOOD. You wouldn’t buy a ski or snowboard or golf club or hockey stick that didn’t flex why a bike frame? I still accept that some people really like the ride of aluminum but most of us are not given the choice. The most popular offroad pricepoints between $850 to $2000 have no steel or ti bike. CALL THE MANUFACTURER AND TELL THEM YOU WANT A CHOICE, THAT YOU WANT STEEL.

    ******RESPONSE TO GIOVAGNS “FRAME MATERIALS”*******

    Giovagn expressed a rather elloquent and well written rebute, however I will maintain my original stance that the overall “real” speed in almost all riding conditions of steel and titainium is near equal to that of aluminum and that the advantage of aluminum is primarialy psychological in that it has a greater percieved speed.

    There is one fundemental flaw in Giovagns argument and that is the idea that flex is primarily a function of the vertical plane, sort of like a full suspension bike. While this flex does occur it is really marginal, second off if you were to lose a race because of too much flex on the vertical plane you would have lost the same race on the basis of bad technique. If the net force of your two legs is primarily in the downward direction you are only using one leg at a time, and we all know this is a bad idea.

    To clarify things one must understand that the flex that I talk about is the twisting that occurs between the handlebars and the bottom bracket, not vertical flex. When one views flex in this way the rebound of the frame is concurrent with the efforts of the rider. The onlw real difference then is the “pop” of the frame, that energy transmitted in that “split second” in a sprint. I will say that the amount of difference in “pop” between steel and aluminum is not a major determining factor in the outcome of a sprint, in which the major factors are raw power over time, timing and position.

    What the difference between the materials would be psychological, do you like the flavor of steel or aluminum, pretty simple.

    lipseal
    Member

    I found this………an old artical but aren’t we all 😉

    Aluminum vs. Steel: the truth about stiffness
    Apr 09 ’01    Write an essay on this

    The Bottom Line Flex is good

    You have all heard the hype about aluminum, how it is ligher faster and better than steel. Accept this for what it is hype. Aluminum bikes are only marginally lighter than steel bikes. The lightest production aluminum frame I know of is the Cu92 Giant XTC frame at 3lbs and only a third of a pound lighter than a 3.3lbs Ritchey P-21. Therefore weight should not be a big concern.

    That leaves stiffness. Aluminum frames are supposed to be faster because they are stiff, because they do not flex, so they are therefore more efficient. This rides on an assumption that flex is inherantly inefficient which is not totally correct. Think back to high school physics, you probably did an experiment with a spring and a weight, you put a small amount of energy into the system and it would go for minutes. It was a really flexy and really efficient system. The only reason it would come to a stop is due to material damping, that is throught the energy moving through the material some of it went out as heat. Ineffecieny in flex is due to the materials damping characteristics.

    So how does this translate to bike frames. Materials like steel and titanium have very low material damping characteristics, meaning that relatively littel energy is lost to heat. That makes sense becuse we make almost all of our springs out of steel or titanium. When you are building up a frame out of these materials you are actually building a spring. On the other hand when one builds a frame out of aluminum they are making the stiffest structure possible, imagine an I Beam. So when you think of flex you shoudn’t think of effiency but rather of the ride of a spring vs. an I beam.

    Imagine a trapoline next to a wood table. Put one person on the trapoline and ask them to jump, do the same with the person on the table. The person on the table will spend the same huge amount of energy everytime trying to jump higher whereas the person on the trapoline would jump much much higher whith the same or less energy expenditure. That is because the person on the trapoline has a temporaily store energy and then use it later when it is more needed. The person on the table can’t do this.

    Now forget about the trapoline and get on your bike on some nice twisty singletrack or a sweet road decent. You lean your bike into a corner, carving a nice right hand curve. Now up ahead you see a tight left hand corner coming up. On the aluminum bike you would need to physically lift the front ent up and over to get it to go the other way, however on the steel bike one simply needs to release the spring to have that energy released, boinging the rider into the left hand carve. A faster and less tiring act than the rider on the aluminum frame. Ride a couple of bikes side by side you’ll see that it is immensely more difficult to hande the really stiff frame.

    This concept reiminds me of a saying in the Italian motorcyle industry “If something is too perfect you tire of it quickly” That is often true of aluminum frames, they are too perfect. In order to make the bike go as fast as it is supposed to go the rider must apply energy at the perfect times in the perfect direction. pull on the handlebars a certain way while cranking with a certain amount of power, and having your butt on a certain perfect point on the seat. This is really difficult to do.

    The Moral of the Story FLEX IS GOOD. You wouldn’t buy a ski or snowboard or golf club or hockey stick that didn’t flex why a bike frame? I still accept that some people really like the ride of aluminum but most of us are not given the choice. The most popular offroad pricepoints between $850 to $2000 have no steel or ti bike. CALL THE MANUFACTURER AND TELL THEM YOU WANT A CHOICE, THAT YOU WANT STEEL.

    ******RESPONSE TO GIOVAGNS “FRAME MATERIALS”*******

    Giovagn expressed a rather elloquent and well written rebute, however I will maintain my original stance that the overall “real” speed in almost all riding conditions of steel and titainium is near equal to that of aluminum and that the advantage of aluminum is primarialy psychological in that it has a greater percieved speed.

    There is one fundemental flaw in Giovagns argument and that is the idea that flex is primarily a function of the vertical plane, sort of like a full suspension bike. While this flex does occur it is really marginal, second off if you were to lose a race because of too much flex on the vertical plane you would have lost the same race on the basis of bad technique. If the net force of your two legs is primarily in the downward direction you are only using one leg at a time, and we all know this is a bad idea.

    To clarify things one must understand that the flex that I talk about is the twisting that occurs between the handlebars and the bottom bracket, not vertical flex. When one views flex in this way the rebound of the frame is concurrent with the efforts of the rider. The onlw real difference then is the “pop” of the frame, that energy transmitted in that “split second” in a sprint. I will say that the amount of difference in “pop” between steel and aluminum is not a major determining factor in the outcome of a sprint, in which the major factors are raw power over time, timing and position.

    What the difference between the materials would be psychological, do you like the flavor of steel or aluminum, pretty simple.

    Premier Icon catfishsalesco
    Subscriber

    I know Sunn use steel in a few of their FS bikes- the Charger, an enduro bike has a alu front triangle & a cromo back end, I think their downhill bike (the radical?) has a similar setup. On that note, does anyone actually sell Sunn bikes in the UK? Loving the look of the charger..

    MrSalmon
    Member

    Imagine a trapoline next to a wood table. Put one person on the trapoline and ask them to jump, do the same with the person on the table. The person on the table will spend the same huge amount of energy everytime trying to jump higher whereas the person on the trapoline would jump much much higher whith the same or less energy expenditure. That is because the person on the trapoline has a temporaily store energy and then use it later when it is more needed. The person on the table can’t do this.

    Eh? I’m imagining trying to jump on a trampoline and not getting very far at all.

    thepodge
    Member

    I think crc do sunn bikes, they aren’t as good as they used to be though

    Premier Icon stevomcd
    Subscriber

    thepodge – sunn stuff is great, owned a couple of their bikes recently. They even do a full-sus with a steel rear-triangle.

    lipseal – that article you’ve copied/pasted is utter pish.

    thepodge
    Member

    I’d seen a few mediocre reviews of their more recent stuff

    Premier Icon stevomcd
    Subscriber

    It’s nothing earth-shattering, but good kit for much cheapness.

    They’ve gone bust (again!) but have been bought out by Look, so next year’s bikes should be interesting.

    We had the Kern LT as our rental bikes and they were excellent – gave the Alpine 160 a very tough run for it’s money!

    thepodge
    Member

    The Sunn Modular S2 looks nice.

    Its such a pity that they cant follow their former glory

    Premier Icon bigdean
    Subscriber

    Anyone made a frame from inconol or other superalloys? How about the some of the metal composites that are around? Theres always someone with too much money who would by one.

    lipseal
    Member

    lipseal – that article you’ve copied/pasted is utter pish.

    Got to keep the forum standards up you know. 😆

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