Steel v Aluminum v Carbon v Titanium Frames...

supersonic

Yep. But scandium tubes are usually less than 2% scandium lol.

Uncle Peter

Ok, Ok once is enough

I just looked at the first line of your post...

'Scandium' is an aluminium alloy,

...and launched in to pedant mode.

supersonic

Lol, I hit it twice!

Yeah, just wish the tube makers wouldn't call them scandium lol: might as well call steel 'carbon'!!!

supersonic

Some things to ponder... Given a tube or rod of equal dimensions:

Stiffness:

1. Steel
2. Titanium
3. Aluminium

Weight

1. Aluminium
2. Titanium
3. Steel

Tensile strength:

1: Steel
2: Titanium
3: Aluminium

As can be seen titanium doesn't excel at any of these properties ;-)

rhext

Always worth reading Sheldon Brown....

http://www.sheldonbrown.com/frame-materials.html

supersonic

Aye, that is a good article that.

Sheldon has been gone 18 months now.

xtreem

supersonic wrote:

Taurine frame getting smashed:

http://www.youtube.com/watch?v=-lsDXEEUlRE

Damn, that frame is strong, and it's a XC one. :shock:
I want one.

Chaz.Harding

supersonic wrote:

Aye, that is a good article that.

Sheldon has been gone 18 months now.

Wow... That long! Is gone quite fast!

And yeah, the Taurine frame withstood a lot of abuse! :shock: :shock: :shock:

Maybe carbon isn't as delicate as most of us first thought....?? :roll:

8)

lesz42

bigchazrocks wrote:

supersonic wrote:

Aye, that is a good article that.

Sheldon has been gone 18 months now.

Wow... That long! Is gone quite fast!

And yeah, the Taurine frame withstood a lot of abuse! :shock: :shock: :shock:

maybe carbon isn't as delicate as most of us firMst thought....?? :roll:

8)

WELL made carbon frames are good, but working with carbon is a bit of a black art, getting it wrong is very easy

took a few years in F1 to get to right


i am thinking of getting carbon bars and seatpost tho!

chrisga

The taurine video is quite interesting. I would not want to use the taurine frame after the first hit with the hammer, but would happily have ridden the other frame with the massive dent in the top tube.
I've had carbon bars and seatposts etc for as long as I can remember with no issues. I also have a carbon framed bike and while I was in the garage knocked a spare wheel that was hanging above it which fell on it fairly hard, cracking the top tube. Before that incident I would have championed the usee of carbon. I am now not totally convinced about carbon for use in mtb frames, not because of the tensile strength but because of impact resistance. Having said that, I will get the frame repaired, because outside of the cycling industry there are a lot of people using carbon tube technology for other things and know how to repair them to the same state, if not stronger than before. Thats another thing that gets overlooked by most....

pte1643

bigchazrocks wrote:

Maybe carbon isn't as delicate as most of us first thought....??

Absolutely.

Been making fishing rods out of carbon for years... And look how much abuse they can take. I got a couple that you can litterally bent into a hoop, and touch the tip to the butt.

Come to think... Has anyone/company ever built a bike frame from Kevlar... Or even Boron Carbide?

physiosteve

Boron thats an interesting 1...?
strong light stiff...
Prince used to make some of there top end tennis rackets out of it

Reckon Supersonic was bang on with his material assessment when he evaluates:-
Stiffness, Weight , Tensile strength:
And ranked Titanium as middle of the rode for each, not excelling at any of these properties.

However damping and the ability to absorb vibration are harder to quantify, somehow in mty experience ti is v good at this.

Ultimately though for me i reckon the very best bikes are going to have a stiff BB to transmit as much power as possible to the trail, but retain vetrtical compliance to take out the buzz of a trail and not hammer your back. I think thats why the latest XC full sus carbon offerings are so awsome

GHill

pte1643 wrote:

Been making fishing rods out of carbon for years... And look how much abuse they can take. I got a couple that you can litterally bent into a hoop, and touch the tip to the butt.

It's not taking any impacts though, which is where carbon is weaker.

Mr_M

Going back to the Taurine video ...

This highlights my one lingering concern about composite frames (for mtb's) based on first hand expeience of composites outside of the bike industry. Yes - it can take impacts (like the inital hammer blows) and show no external signs of damage - but the key words there are "external signs". Those blows may well have caused damage within the inner layers of the composite laminate - trouble is that without testing the tubes thoroughly you can't be sure.

Of course the next problem here is that testing composite frames is in itself not that easy - you can use x-rays - but they will not always show cracks that have not propogated through the frame, you can use ultrasonics - but you need an experienced operator who really knows what they're looking for. All this is both time consuming and expensive - and at the end of the day still not 100% reliable - hence why a lot of repuatable frame manufacturers simply replace composite frames under waranty rather than testing them and passing them "OK".

Now don't get me wrong, I'm not saying that the same impact wouldn't damage a steel/alu/ti frame - it would. But (and this is the crucial difference for me) you'd immediately be able to see the damage.

pte1643

GHill wrote:

pte1643 wrote:

Been making fishing rods out of carbon for years... And look how much abuse they can take. I got a couple that you can litterally bent into a hoop, and touch the tip to the butt.

It's not taking any impacts though, which is where carbon is weaker.

True enough.

Was just an analogy to show Carbon Fibre as being pretty resilient stuff.

Fishing Rods = Strong and Ultra Flexible, whereas bike (car, mbike, boat, plane) frames/parts need to be stiff(er).

F1 was mentioned earlier.
F1 suspension parts are super strong in their "natural" up-and-down axis, but hit it from the front/rear and they break.
It's all in the way it's constructed...

Unarce

Sorry if someone said this already...I skimmed through most of the thread. A great bike can be made from any of the 4 materials. Just depends on the builder.

However, most of the big manufacturers are sinking tons of marketing dollars into carbon because of the huge margins. Simply put, carbon is a super cheap to make and it's more profitable.

Some are seeing past the hype.

If I'm a pro who gets sponsored to ride free bikes, carbon is cool. If I'm the company supplying the bike, a carbon model will cost me less.

The rest of us just want a bike that fits properly, is mostly trouble-free, and will give me at least 5-10 years of enjoyment. And if you need a little bling...Titanium is still king.

Surf-Matt

Steel pros:

Has a natural spring
Easy to fabricate
Numerous types of steel
Easy to repair
Extremely durable

Steel cons:

Can corrode
Heavy
Steel prices (high grade) still high
Hard to shape - so "tubes" have to be used

Alu Pros:

Lightish
Fairly easy to shape
Stiff
Still fairly cheap

Alu cons

Fatigues then can fail easily
Weak for it's weight so large sections have to be used
Hard to weld/fabricate

Ti Pros

Light
Strong
Has a natural spring
Durable

Ti cons

Very expensive
Hard to fabricate

Carbon pros

Light
Can be formed in almost any shape
Stiff along certain axes
Has a slight spring

Carbon cons

Expensive
Poor impact resistance
Fatigues
Very hard/impossible to repair
Difficult to combine with "fitting" such as headsets, stems, seatubes, etc

supersonic

A lot still does depend on how the frame is built up. Steel is by far the stiffest material, and aluminium actually the flexiest, so those tube profiles have a huge effect on the final frame characteristics.

Carbon can be made to have high impact resistance if need be ie some are using specially formed layers under downtubes for protection. The prices will drop as the material becomes more common., just like aluminium frames have.

Surf-Matt

Supersonic - my list concerns frames made of the materials specified rather than properties of the materials themselves - clearly steel has to be tubular, ti generally is but alu and carbon can be any shape.

You can reinforce carbon but it'll need to be thick. Any weave/resin is stiff but easy to pierce.

supersonic

I guess what I am saying is that there are always exceptions. The stiffest frames on the market are usually the heavy, oversized steel ones, yet at the same time, the most flexy are the very light steel ones. Strength to weight (UTS) of 7005 alu is actually higher than that of the common 4130 cromo we see.
Kevlar is woven aramid and is incredibly pierce resistant. I think GT uses it on the Fury.

bails87

supersonic wrote:

Kevlar is woven aramid and is incredibly pierce resistant. I think GT uses it on the Fury.

Isn't that what stab vests are made from?

supersonic

Some are, yep.

Anonymous

ive got a helmet made out of kevlar

Surf-Matt

Woven aramid is quite different in strucuture to a carbon matrix bonded with resin. But yes - it's super pierce resistant, hence bulletproof stuff being made from it.

covelove

am i right in thinking that allthought carbon kevlar is strong and perhaps puncture resistant and is now used in products like helmets and kayak paddles does it not splinter and flake after impact? any experience of this on the fury?

conad

jamsop wrote:

Interesting thread.

If Ti material doesnt really cost that much more material wise.

Welding is welding right?!?!.
.

oh how wrong could you possibly be

GHill

covelove wrote:

does it not splinter and flake after impact?

I'm not sure what "carbon Kevlar" is (the latter being a trademark of DuPont), but if Kevlar splinters after impact it would make terrible body armour. The bullet might not kill you, but shards of armour would probably take you out of the fight.

Note, while I'm a Chemist, I don't know much about body armour.

joshtp

kevlar is almost like a fabric, it is imensely tear, wear, and pierce resistant, it does not flake or splinter, so in theory a kevlar content should improve impact stregnth of carbon. it would also make a great top layer... although it is very ugly.... kinda yellow....

covelove

I dont think it is always in that yellow colour (see bottom link) and i agrre that it is tear resistant but by splinter i mean very small tears and shards coming off, i have seen it on paddles before but was wondering if bike would be the same?
excuse the non bike links!

http://www.paddleobeco.ca/paddles.php

http://www.dreamgate.ne.jp/NSR/forsale/bodywork.html

bike-a-swan

big advantages of composites:

the ability to make complex shapes in single pieces where another material may require multiple sections

the properties of carbon fibres are only effective in one direction. therefore the exact properties of any given structure can be tailored to different directions (stiff side to side, flexes fore aft, etc) depending on the layup (mix of directions of different layers of fibres) used . i think the seatpost on the new flash is a good example of this.

you can blend different fibre materials in the same composite to play with the properties as well. for example: http://www.bikeradar.com/news/article/museeuw-flax-bike-launch-15198
i'm also pretty sure that the new remedy uses high strength rather than high modulus (ie stiffness) fibres to deal with 'toughness' issues.

in summary then, composites have the potential to be a lot more adaptable in their application if used correctly. that said, two of three of my bikes are steel, and i have a real hankering for ti!