What are the pros and cons of steel, aluminum, magnesium, titanium and carbon?
>>891763
>carbon
Best combination of weight, strength, stiffness, compliance, and aerodynamics, however it is not as mature a technology of metals. Contrary to popular belief, carbon is not fragile and does not suffer from fatigue, but it can be very difficult to tell if carbon is damaged or has cracks that will lead to more catastrophic failure down the line. Metal is malleable, and will bend, crease, and it is easy to see cracks before it breaks completely. Carbon is either expensive or of questionable quality control.
>titanium
As light as aluminum, more flexible than steel. Extremely expensive due to material costs, and while titanium doesn't normally suffer from fatigue as aluminum does, but the difficulty in welding leads many titanium frames to crack near the welds. Like aluminum it doesn't need to be painted, and many technogeeks find titanium a very prestigious metal. In addition to the high costs that make it cost as much as carbon, titanium's weak point is the flexibility and difficulty of forming complex shapes, meaning the chainstays can not be very stiff.
>Magnesium
Don't make them like that anymore. There were some innovative cast magnesium designs, but those have become irrelevant with advances in hydroforming.
>Aluminum
Cheap and light, the default frame material for a modern bike. Aluminum suffers from fatigue, but an aluminum frame will last the designed lifetime of the product, usually for a few decades. That makes them lack the timelessness and permanence of other materials and makes them part of a consumer culture, but most people will be willing to buy a new frame in a few decades. Cheap ones have a reputation of having a poor ride. Aluminum is easy to hydroform though, and like carbon can be designed to have various ride characteristics, and even some degree of aerodynamics. The problem is expensive aluminum frames often exceed the cost of cheap carbon frames.
>>891768
And steel?
>Steel
Not any cheaper than aluminum, in some cases as expensive as carbon. They rust. Some people claim you can repair them, but it's almost always just cheaper to replace. Some examples have lasted many decades, if not over a century, if in fact you feel compelled to hand it down to your grand children as an heirloom, assuming that they want your cruddy old bicycle, it it hasn't been destroyed in a crash between now and then. Lauded for ride quality, the better carbon and titanium frames at least match it. The biggest advantage is the durability and the fact that it is old technology, meaning you can readily buy it on the second hand market. It's also has lots of tradition, since bicycles have been made with steel for much longer than any other material. You can increase the performance to be as light as heavy aluminum but price increases astronomically and durability plummets. It is difficult to separate vertical compliance from lateral stiffness using round steel tubes, and the availability of actual aerodynamic steel tubes is next to none.
That being said, second hand steel is good enough for most people, and it's been good enough for many many decades.
>>891773
>Steel
Is real.
>steel
Durable, lasts a lifetime, endurance threshhold (it can be bent to a certain extent infinity times and not break), easily repairable, comfortable to ride, cheap, heavy, rusts
>alu
Stiff, uncomfortable compared to other materials, good for racing, cheap, light, no endurance threshhold (even bending it very minorly will weaken it permanently), repairing damaged alu is not cost effective, does not rust
>magnesium
lol no one uses it
>carbon
Expensive, very light, comfortable, stiff, good for racing, repairable but expensive to repair (a few hundred dollars for minor damage), no endurance threshhold (even minor bending will permanently weaken it), may or may not last a lifetime, no real use outside of racing, can be shaped in more aerodynamic ways than metal tubing, makes people think you are cool, makes people think you are a fred, makes people want to steal your bicycle, does not rust
>titanium
Best in every way except more expensive than everything else, comfortable, strong, endurance threshhold (can be bent a little bit infinity times and not break), repairable but expensive to repair, good to race, good to ride, makes people think you are awesome, makes people want to steal your bike, like steel but lighter and does not rust, stiffer than steel but not super stiff making it comfortable and responsive, hard to weld/repair which is why it is expensive, the one non-money downside is that it won't be as aero as some carbon tubing, best material for pretty much everything (except commuters because it appeals to thieves, and aero bikes because carbon can be more aero, and third world touring because steel is easier to repair), the kind of bike that God would ride if God was real *tips fedora*
http://www.ibiscycles.com/support/technical_articles/metallurgy_for_cyclists/
>>891768
>carbon ... does not suffer from fatigue
False. Carbon has an endurance threshold.
>>891778
/thread
>>891796
And?
>endurance threshhold (it can be bent to a certain extent infinity times and not break)
>no endurance threshhold (even bending it very minorly will weaken it permanently)
>no endurance threshhold (even minor bending will permanently weaken it)
>endurance threshhold (can be bent a little bit infinity times and not break)
>>891763
>walk into lbs
>huge grin on face
>dick is erect
>slam fists on counter
>"one magnesium bike please"
>>891805
And therefore carbon will fatigue over time because each time it bends even a microscopic amount (flexing under rider's weight, etc) it weakens.
Regardless of material manufacturing techniques play a large part on the final quality of a frame. Any metal frame could suffer from a shit welding job, poor choice of tube gauge / diameter, improper heat treatment.
With carbon people are drawn to the lightest possible frames. Someone could make a heavier super tough frame but they probably couldn't sell many because it is not as light as its competition.
>>891826
Not true. Carbon can be made flexible if needed, even used as a spring in some cases. Still, carbon frames are generally stiffer than their metal counterparts in some places with flex added where needed/desired.
>>891828
>Carbon can be made flexible if needed
It still has an endurance threshold and therefore fatigue life. Sure, it will take a lot to produce non-negligible fatigue, but it does fatigue.
>>891826
You can't even keep your definitions straight, why should anyone take you seriously?
>>891827
And materials costs go up the more carbon you use, where as materials costs go down with steel the more you use.
>>891829
Every time you hit a pothole your steel frame fatigues. Carbon does not meaningfully fatigue. There's some cases where the composite will become less stiff when the a small portion of the resin bonds crack on a microscopic level, but the carbon strands themselves do not fatigue and keep virtually all their integrity, and fatigue is essentially a non-issue.
There's a reason why steel, titanium and composite springs exist, but not the case for aluminum except some very niche and undemanding applications.
>>891829
I don't think the minute flex that the typical carbon frame sees will cause any damage within the expected life time of the frame. Yes if it flexes too much it will cause damage, say for example you tried stretching some dropouts, but the same can be said for aluminium.
It's like saying that being magnetic is a downside of steel frames. Sure it's technically correct and could be a concern in theoretical situations, but in the real world it just doesn't matter.
>>891834
> the same can be said for aluminium
The same could be said of any frame material.
>>891833
>You can't even keep your definitions straight, why should anyone take you seriously?
What definition did I not keep straight?
>Every time you hit a pothole your steel frame fatigues.
False.
>Carbon does not meaningfully fatigue.
Long-term it does.
>There's some cases where the composite will become less stiff when the a small portion of the resin bonds crack on a microscopic level, but the carbon strands themselves do not fatigue and keep virtually all their integrity, and fatigue is essentially a non-issue.
We are talking about carbon fiber, not strictly the carbon itself. If your bike explodes I don't think you'll care whether it was the epoxy or the carbon strands that gave.
>>891834
Mostly agreed.
>>891835
Not for steel or titanium (unless the flex is substantial). Read the thread and look up "endurance threshold". Steel and titanium have it. Carbon fiber and aluminum do not.
>>891837
You said
>Carbon has an endurance threshold.
>False.
True.
>Long-term it does.
Not really.
>We are talking about carbon fiber, not strictly the carbon itself.
Carbon fiber is the carbon itself, you mean composite.
>If your bike explodes I don't think you'll care whether it was the epoxy or the carbon strands that gave.
Except it doesn't happen to that extent. There's an initial softening of carbon composites if they're pushed past a certain limit as the weak places fail. It doesn't extend to a larger structural scale.
>Not for steel or titanium (unless the flex is substantial). Read the thread and look up "endurance threshold".
It's not infinite. There's a reason why it's called a limit, or threshold as you call it.
But good job being poor kid with an old 10 speed and aspiring to a titanium bike.
>steel is reel
>muh fatigue
>muh sheldy brown
http://www.sheldonbrown.com/rinard/EFBe/frame_fatigue_test.htm
>>891844
>>Carbon has an endurance threshold.
Sorry, that was a typo. Meant to say it does not.
>True.
Nope, steel has an endurance threshold
>Not really.
Whether or not it is non-negligible is a separate issue. I never claimed whether or not it is.
>Carbon fiber is the carbon itself, you mean composite.
Again, no one gives a fuck. If the frame breaks, it's broken regardless of why it broke. Also, "carbon fiber" often refers to the composite, see https://en.wikipedia.org/wiki/Carbon-fiber-reinforced_polymer
>Except it doesn't happen to that extent. There's an initial softening of carbon composites if they're pushed past a certain limit as the weak places fail. It doesn't extend to a larger structural scale.
It can lead to the frame as a whole weakening and therefore failing.
>It's not infinite. There's a reason why it's called a limit, or threshold as you call it.
The limit refers to the amount it can be stressed infinitely, not the amount of times it can be stressed to a given amount.
>But good job being poor kid with an old 10 speed and aspiring to a titanium bike.
I have multiple bicycles, some steel and some carbon, including an old ten speed. And yes, I would like to get a titanium bicycle. I probably will get one.
>>891846
Keep making things up kid
>>891849
And before you point out there are aluminum carbon frames that failed from fatigue, the Time Carbon had the highest fatigue cycles of any frame that failed, better than all the other steel and Ti frames. The Klein had more cycles than any steel frame and the Stevens did better than most of the steel frames, falling short only of the Barellia.
>>891768
H-has anyone ever tried making a lugged titanium frame?
>>891852
Jamis Eclipse was part carbon, part titanium, and lugged.
>>891768
You can still get magnesium frames, Zinn yo
>>891916
I'm honestly not sure why you would do that. The only advantage of magnesium tubes is round magnesium tubes might be a bit better than round aluminum tubes, which is only an advantage for custom fabrication. Otherwise you just hydroform the aluminum for improved performance.
>>891822
underrated
my4 rides., titanim,, alulmum,, steal,,, glass.
imeso confus.
>>891852
Lugs are for brazing. Titanium is always tig welded
Carbon can be built to be as strong as steel for example carbon MTB frames will have a better strength to weight ratio than steel MTB frames which why you never see steel MTB frames. The low mass of carbon allows frames with a lot of thickness but weight quickly becomes excessive when you thicken steel. Unfortunately no one makes road frames that are strong because there is too much if a temptation to take advantage of the inherent lightness of carbon which is why carbon road bikes will easily break under heavy load or impact
>>893209
There's some steel is reel meme rigids and hardtails, but that just shows you that they cater to retrogrouchy people. In a full susser, there's no disadvantage to stiffness. You don't want frame flex to absorb shock, you want your tuned suspension system t do it.
>>893209
>Unfortunately no one makes road frames that are strong
How heavy would a strong carbon road bike be?
How heavy would a strong carbon [spoiler]tourer[/spoiler] bike be?
>>893221
Probably ~2/3's the weight of an equivalent steel frameset, which is probably a bigger difference in weight than going from hiten shit to nice steel.
>>893224
What about alu?
Nah, who am I kidding, I won't be able to afford that sexy carbon tourer even in a decade.
>>893221
Guessing roughly I'd say 4 pounds
