Carbon vs Titanium???

[Christie]

Firstly' date=' Carbon Fiber and Graphite are not the same material. They are isotopes! Graphite flexes, something you wouldn't want in carbon fiber. However, due to carbon fiber not flexing, there is a big fatigue factor with the material.
[/quote']

 

Graphite referred to here is what is called carbon in the common tongue.

 

The other graphite, possibly what you are talking about (as is used in a pencil) does not flex very well at all.

 

It could possibly be made into a composite (actually ceramic is the better word), but with great difficulty, by adding some fibre reinforcement - lots of heat and pressure needed. It would make a poor frame material, but it is good for stopping neutrons, I think.

Christie2008-06-25 11:14:24

[Speedi]

look carbon is the best for weight and stiffness, but different strokes for different folks. if Ti was SOOO fabulous the pros would be riding it. it might feel nice but what about the stiffness? and is Ti responsive like carbon?

[Speedi]

 

<span style="font-size: 7.5pt; color: black; font-family: Verdana;" lang="EN">

Below is a fatigue curve from a fatigue and fracture course by Dr Neil Bishop. (Specific fatigue strength is stress/density). The graphite epoxy (or what we call carbon) vastly outperformes the rest' date=' that is why F1 syspension arms are made from carbon, instead of Ti like long ago.

 

</span>[/quote']Firstly, Carbon Fiber and Graphite are not the same material. They are isotopes! Graphite flexes, something you wouldn't want in carbon fiber. However, due to carbon fiber not flexing, there is a big fatigue factor with the material.

 

 

 

 

 

but who wants to keep a frame for more than 5 years?

 

 

 

 

 

 

 

Speedi152008-06-25 12:06:43

[swift]

Some interesting reading... you decide for yourself.

 

 

 

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

[Racer X]

I ride a Ti MTB Hardtail and am super happy on it. The only downside I see in carbon is that is has no impact strength, wrong term I know. What I mean by this is that it has no protection against any sort of "Blunt Force Trauma". Simply put, if your carbon frame lands on the corner of a brick wall its quite likely that'll crack.

 

Titamium is stronger in this regard but as a "Steel," it will have more flex.

 

Just my views.

 

I would go for the Litespeed, (personal preference)

 

http://www.litespeed.com/bikes/2008/ghisallo.aspx (My dream frame).

 

I wonder how long it'll take Johan Bornman to reply to this thread.

   

[THE BODY CENTRE]

intentional hijack (sorry Spaceboy)

 

Just a reminder that this one is still looking for a Ti lover

https://www.bikehub.co.za/forum_posts.asp?TID=26497&KW=litespeed

 

**h/j off**

[Racer X]

After a quick google:

 

Scott's Addict LTD comes in at 790 grams which includes fork, intergrated seatpost, headset and seatpost clamp.

 

Litespeed's Ghisallo comes in at 770 grames for frame. Add to this 8 grams of extralite seatpost clamp, 130 odd grams of schmolke seatpost, 58 grams of crankbro's headset and approx 220 grams for a THM Scapula fork.

 

Thats a total of 1186 grams opposed to 790 grams for the scott.

 

I still want the Ghisallo.

 

Ronelle, I hate you.

Racer X2008-06-25 13:13:35

[THE BODY CENTRE]

i know what you mean -- there is something about a Litespeed ... Maybe its got the elusive 'x factor'

 

but hey -- this thread is all about Spaceboy ...and what he loves

[GT oke]

Carbon Carbon Carbon!!!

TI is really good and nice and everything but i dont like the style of a litespeed bike and is a ugly bike for me!

[Christie]

Some interesting reading... you decide for yourself.

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

 

 

I agree with most of the article. One or two small errors.

 

.... downside I see in carbon is that is has no impact strength' date=' wrong term I know. What I mean by this is that it has no protection against any sort of "Blunt Force Trauma". Simply put, if your carbon frame lands on the corner of a brick wall its quite likely that'll crack.

[/quote']

A few comments:

1. Bicyles are not designed to crash.

2.It is possible to make a carbon composite frame that can stop bullets, but it would be heavy. Aramid fibes have got colossal impact strength, but crappy stiffness. Layers of these could be added to a frame layup, but it would be heavy.

3. So yes, I agree, the composite frames we ride have not got the greatest impact resistance, but a big crash can break any frame, regardless of material. If a Ti or steel frame hits that corner of the brick hard enough, they will get big dents. I would not buy a carbon mountainbike frame for myself, I crash too much!

 

 

 

 

 

I wonder how long it'll take Johan Bornman to reply to this thread.

   

I hope he does! JB knows what hes talking about, and can conduct a proper debate.

Christie2008-06-25 13:23:17

[Racer X]

...and what he loves is Litespeed.

[Racer X]

Some interesting reading... you decide for yourself.

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

 

 

I agree with most of the article. One or two small errors.

 

.... downside I see in carbon is that is has no impact strength' date=' wrong term I know. What I mean by this is that it has no protection against any sort of "Blunt Force Trauma". Simply put, if your carbon frame lands on the corner of a brick wall its quite likely that'll crack.

[/quote']

A few comments:

1. Bicyles are not designed to crash.

2.It is possible to make a carbon composite frame that can stop bullets, but it would be heavy. Aramid fibes have got colossal impact strength, but crappy stiffness. Layers of these could be added to a frame layup, but it would be heavy.

3. So yes, I agree, the composite frames we ride have not got the greatest impact resistance, but a big crash can break any frame, regardless of material. If a Ti or steel frame hits that corner of the brick hard enough, they will get big dents. I would not buy a carbon mountainbike frame for myself, I crash too much!

 

 

 

 

 

I wonder how long it'll take Johan Bornman to reply to this thread.

   

I hope he does! JB knows what hes talking about' date=' and can conduct a proper debate.

[/quote']

 

Okay so bikes are not designed to crash, yet, as you yourself stated in your 3rd point these are inevitable. I just like reassurence, dodgy spelling, of Ti.

 

[Johan Bornman]

Christie is right, carbon is by far the best material for bicycle frame construction and the only drawback of carbon that I can think of is crash resistance. If a carbon frame falls on a sharp object such as a ledge, it turns to pulp, rendering the frame useless and non repairable.

 

Titanium would bend and survive that same fall. However, titanium is relatively heavy (half the weight [density] of steel but, and this is where fashion over-rides common sense, twice as heavy as aluminium.

 

Although alu is not as strong (cycles to fatigue, yield strength and the like), it can be made into a very stiff and durable frame a la Cannondale.

 

Titanium is hard to work with (it gets harder as it is machined) and is prone to cracking at welds. It is more expensive to heat treat than aluminium and easier to get wrong. Titanium is purely a fashion material when it comes to bicycles and has no quality that makes it better than steel or aluminium in the metal bike category nor in the carbon fibre category.

 

It doesn't oxidise at room temperature so it remains shiny, unlike steel and alu. Most people won't be able to pick out titanium from similarly polished steel or alu, so unless the beholder knows it is ti, he/she won't see the beauty in what they're looking at.

 

Finally, I'm glad Christie mentioned that fact that steel (or the other bike metals) never get soft from age and use. They remain as stiff as they left the factory.

 

Unfortunately the cycling god Bernard Hinault doesn't know that. In the May edition of the revered Cycling Sport he says: "....whereas steel, composed of a more malleable arrangement of atoms [vs carbon], moves over time. We can sense it when we get a new bike at the start of the Tour. We have the sudden feeling of having a rigid bike, proof that the one we had before had lost is quality over the months...."

 

Even the gods spew rubbish and cycling magazines are just too eager to print it.

 

And finally, guys, please stay away from meaningless terms like "responsiveness." It has no root in bicycle science.

 

Johan Bornman2008-06-25 13:33:08

[Christie]

 

Okay so bikes are not designed to crash' date=' yet, as you yourself stated in your 3rd point these are inevitable. I just like reassurence, dodgy spelling, of Ti.

 

[/quote']

 

I've got very limited MTB skills. The best frame material for my MTB would be aluminium. A mtb gests exposed to more water, which rules out steel. Mtb's have got suspension forks, fat tyres with low pressure, so ride "feel" will be dominated by the fork, tyres, and frame angles.

 

For a mtber weight weenie, with good skills, and money/insurance to replace/repair in case of some mishaps, I suppose a carbon frame is OK. 

[ewep]

 

Crash a Ti bike and you get up and continue riding' date=' crash a carbon bike and it has a big chance of needing replacement. When carbon breaks, it breaks catastrophically, but it is almost impossible to break Ti, although you may bend it with extreme difficulty.

[/quote']

Depends on the crash! Ewep wrote off his ti Colnago the other day riding into a car. Bicycle frames are not designed to crash. Not having frame damage after a crash has much to do with luck.

 

OK, my take:

1. You crash a bike (Carbon, Ti, Alu or Steel in a decent crash) and the structural integrity (don't know if the technical mumbo-jumbo is correct) is stuffed.  I will not ride it after that!!!
2. Yes, I wrote off a Ti frame, but I do think that if I was on my 'dale I would've had more serious injuries, i.e. cuts, etc., from the break in the carbon.  The Ti was bent, but did not shatter!

3. Ti is nice, but as JB says, it's a "status" thing.

When buying a bike I would rather look at the frame geometry than just the "material".  Why:

1. I rode a Ti Colnago.  The bike had a more relaxed geometry than my other bikes, so on long days I had a more relaxed ride with less "road stress" on the body.  But the bike didn't feel as "nippy" as the 'dale in bunches.  The 'dale on the other hand is twitchy but has a more radical geometry.

2. The System6 is more bumpy on the road (same wheel set as on the Colnago).  So looking at this I think an Alu frame will allow more road "noise" to rise through the metal than the Ti. (the System6 has a alu rear triangle).
3. The System6 is much easier to climb with while standing than the Colnago, once again, frame geometry.

Finally, if both the geometries are EXACTLY the same, and you want "something else" then go for Ti.

 

[Johan Bornman]

I beg to differ Christie' date=' you are so misinformed. Ti frames have a lifetime guarantee, something I have never seen on a carbon frame. Fatigue is almost non-existent in Ti which is why it is so prevalent in the aeronautical and space industry. Crash a Ti bike and you get up and continue riding, crash a carbon bike and it has a big chance of needing replacement. When carbon breaks, it breaks catastrophically, but it is almost impossible to break Ti, although you may bend it with extreme difficulty. Bottom line is carbon is cheap and easy to make which is why it is popular and why there are a gazillion Taiwanese carbon frame manufactures out there all competing for a small slice of the market. By the way, the lightest frame you can buy is a Litespeed, and with geometrically enhanced tubing, there is no evidence that they are any more flexible than the equivalent carbon frame and it will outlive any carbon frame. Carbon bikes are very decent mass produced commodity frames for the general populace while Ti bikes are hand crafted, guaranteed for life, bullet proof equivalents ridden by the connoisseur for whom money is no obstacle!<?: prefix = o ns = "urn:schemas-microsoft-com:office:office" />

[/quote']

 

You give titanium far more credit than it deserves. As Christie demonstrated in his graph, titanium does fail from stress and quicker than carbon.

 

I also won't use the word "extreme" with tatanium. It's tensile strength is half that of steel and about double that of aluminium. The way I see it, titanium is just a strong, corrosive-resistant aluminium.

 

The fact that they're gauranteed for life is neither here nor there. It is not an engineering fact, just a marketing ploy.

 

I agree that they've made some beautiful ti bikes, but if they were lacquered aluminium, very few people would have known.