Comments on: Aluminum vs. Carbon fiber vs. Titanium

By: Superhandyman

Superhandyman — Sun, 07 Mar 2010 18:37:40 +0000

I am no scientist, but that demonstration did not impress me. I have been demolishing bikes at least once a year since x-mas 1979. No one mention using a composite of materials in the same frame. Using carbon fiber reinforcements where tension is required and Titanium where compression forces would be necessary we optimize the “strenght” of the frame. I believe that there are companies already using these technologies. Check out Titus exo–whatchmacallit frames. Can anyone here demonstrate the exo-thingy material vs. Titanium alone? — on video obviously.

By: Anonymous

Anonymous — Thu, 12 Nov 2009 19:32:53 +0000

you guys are all stupid. they just did a demo messing around, and now u all act like this is the next superbowl commercialfor marketing. relax and shut up.

By: Anonymous

Anonymous — Sat, 05 Sep 2009 18:45:47 +0000

This thread is in desperate need for a materials engineer.

Carbon fiber is a *fiber*.

A *fiber*.

When it comes to stresses, two of the most basic types are compression and tension (bending, shear, torsion are others).

Summarizing a material's endurance of these stresses to a single word - "strength" - is woefully inadequate.

While carbon fiber's tensile strength is ridiculously high...

YOU CAN'T PUSH ON A ROPE.

In other words, carbon fiber *as a fiber* offers no meaningful compressive strength.

When a carbon fiber composite tube endures a compressive force, it would be accurate to say that pretty much all of the compressive load is taken on by the "composite" part of the material only.

Now if the video demonstrated a truck attempting to pull these tubes apart, the carbon fiber tube would have performed more admirably. But it didn't, because this wasn't a tension test, this was a compressive strength test.

So to summarize:
1. Materials do not have one "strength".
2. You can't push on a rope.
3. "Stronger" does not simply imply "better". "Stronger" only is "better" when it's taken to in the context of "more appropriate for its environment".

So while carbon fiber failed miserably in this demonstration of compressive stress, this does not mean that titanium is "better" than carbon fiber. What this demonstration concludes is a titanium tube is much better at resisting a compressive load than a carbon fiber tube!

So does this mean a titanium tube "better" than a carbon fiber tube?? From what this video demonstrates, only in situations/environments where it will be subject to high compressive stresses!

So you people with carbon fiber bikes and fragile egos can just relax.

Now this doesn't mean resisting compression is all a titanium frame is good for (vs a carbon fiber frame). There are other qualities too. But those are for other clueless discussions following other video demonstrations...

By: Anonymous

Anonymous — Sun, 09 Aug 2009 03:16:28 +0000

The overwhelming choice of frame material at the 2010 Tour De France was and will continue to be Carbon Fiber. Case closed. If I ever decide to race my bike underneath a truck wheel, I'll buy Ti.

By: Anonymous

Anonymous — Thu, 09 Jul 2009 12:12:34 +0000

regardless of the variables, the ti is stronger than any of the other materials. that doesnt mean that its better for a frame. it adds a high priced option to those looking for something extremely durable. EVERYONE knows that when carbon fails, and it will, it fails catastrophically. aluminum is used by huffy, pacific, murray etc… even carbon is being produced in cheap. pinarello uses magnesium for gods sake. magnesium burns at a pretty low temp. buy what feels good.

By: Bici

Bici — Wed, 07 Jan 2009 01:40:00 +0000

Hi All!

What material do you recommend for a road bike?
Very important:
- lifetime and
- as comfortable as possible
Important:
- weight
- stiffness

Thanks!

By: Anonymous

Anonymous — Thu, 30 Oct 2008 18:22:00 +0000

I snapped an ’09 Specialized Roubaix elite in two a week ago. Beautiful full carbon. I’m not sure if I’ll go carbon or steel for replacement. I think the important thing about materials is suiting your needs. I have a habit of destroying bikes, but I know certain materials accelerate faster. People shouldn’t be personally attached to materials. I’ve got an aluminum bike that I love, and I’ve got a lovely custom Ti bike also. But I’m not going to say “ooh! Ti beats carbon!” Carbon is torsionally stiff. Ti is absorbant. Steel is real. What can I rhyme with aluminium? Come on people.

By: Anonymous

Anonymous — Fri, 18 Jul 2008 21:11:00 +0000

Does this mean Litespeed’s are over-engineered and heavier than necessary?

By: Anonymous

Anonymous — Tue, 08 Jul 2008 11:12:00 +0000

I am mechanical engineer and a cyclist weighing 100kg.
I have owned several frames made from steel, aluminium, carbon and titanium.
2 steel frames failed close to braze area. Titanium (litespeed) failed at headtube to downtube weld. Carbon trek Madone and carbon Specialized Roubaix have not failed.
All failures occurred during riding.
I think my experience is more valid than the Litespeed test video.
Titanium is a supreme material where tensile strength and durability are concerned, but as soon as it is welded there is a weakness introduced.
I have heard of so many Litespeed frame failures. Mine failed after 3 months, Litespeed would only repair the frame and it would take 6 weeks minimum, no replacement or refund was offered.

Andy T

By: Anonymous

Anonymous — Tue, 27 Nov 2007 20:01:00 +0000

well, i ran into a car (that appeared from nowhere on the cycling path) at around 22km/h. Not that fast, but it was front impact. Just got the news: my titanium frame looks pretty, but it’s not. Have to change the whole bike (except the rear wheel). Loved my ti for ten years, gonna get a new one (still… cuz it never dents, stays nice, never rusts). As for resisting impact, imoho, nothing does except a good helmet (went right thru her window). Never thought i’d damage my ti like that. Just depends on HOW you hit it I guess…