Originally Posted by Trakhak

You mean they couldn't use it because of wartime restrictions, correct? Not clear from the context whether you mean that or that they couldn't use it for reasons that made aluminum a bad choice for building airplanes.

Originally Posted by tomato coupe

Strength-to-weight isn't everything when it comes to material science. If it was, wooden bikes would have dominated steel and aluminium bikes in the pre-carbon fiber era.

Originally Posted by tomato coupe

Strength-to-weight isn't everything when it comes to material science. If it was, wooden bikes would have dominated steel and aluminium bikes in the pre-carbon fiber era.

Originally Posted by Kontact

Virtually all metal airplanes are aluminum. A few are Ti. Even fewer are steel. The winga of the Japanese Zero fighter were wood.

Originally Posted by tomato coupe

The use of virtually all metals was restricted by the U.S.government during WW2.

Originally Posted by tomato coupe

What's your point? Why are you taking us down this Spruce Goose and Japanese Zero rabbit hole?

Originally Posted by Kontact

Because they demonstrate that the specific strength numbers I mentioned are valid. This thread is full of misunderstandings about how materials are used to make light bikes, as well as some strange statements about their fabrication.

Originally Posted by tomato coupe

How does the Spruce Goose and Japanese Zero demonstrate anything about specific strength?

Originally Posted by Kontact

Because a fighter and a heavy transport have high wing loading and need to be low weight. The Zero was an excellent fighter, the Goose the largest plane to date. Materials are important in aviation. That's why the bike industry keeps looking to aviation solutions.

Originally Posted by tomato coupe

And, no, the Spruce Goose was not the biggest plane.

Originally Posted by tomato coupe

That has very little to do with specific strength, which you have oddly fixated on. Tensile strength, stiffness (Young's modulus), fatigue strength, and elongation are bigger factors in frame construction. And, no, the Spruce Goose was not the biggest plane.

Originally Posted by smd4

I think he meant in the 1940s.

Originally Posted by Kontact

None of those numbers refer to the weight of the finished product. Specific strength is tensile strength over density. It is the reason we use so much carbon and aluminum despite their comparably low strength to steel. Carbon is strong by weight, not by volume. Tensile strength is by volume.

Originally Posted by tomato coupe

Clearly not:

Definition of 'to date'

to date

PHRASE
To date means up until the present time.


No, specific strength is not why carbon fiber and aluminium are used for bike frames. If it was, then balsa wood (521 Nm/g) would be better than Aluminium (204 Nm/g) or CrMo steel (71-85 Nm/g). Have you seen a lot of balsa wood bike frames?

Originally Posted by Kontact

Ti bikes are TIG welded. Are you confusing them with vacuum brazed ti in the 70s?

You sound like you're making this stuff up.

Originally Posted by Kontact

The lightest 953 frame I found is 1175g. Allez DSW SL or Caad frames ran 1050-90.

The limiting factor with advanced steel alloy is wall thickness and the "beer can effect".

Originally Posted by Kontact

I think you missed the fact that the Zero and the Goose were covered under the same verb "was", referring to them contemporaneously. Of course I was speaking of that time - to that date. The Antonov is the biggest airplane now.

Originally Posted by Kontact

Well, you go ahead and try to make a bike out of something as soft as balsa. You'll quickly find that balsa makes it hard to anchor things like hubs, headset bearings or cranks. The Q factor would be outrageous since the BB would have to be about 10 inches wide.

However, for something like a glider wing balsa is great for large, light sections that need to be stronger than foam.

Originally Posted by elcruxio

Tig welded with either shielding gas or in the best case in a vacuum chamber.



Yes and? Were we not discussing strength? Now it's suddenly frame weight. You can do things with aluminum you can't do with steel. You can do stuff with carbon fiber you can't do with steel. None of that is new. But steel is still stronger than aluminum. Yet strength isn't everything or we'd be making frames out of UHMWPE.

Originally Posted by elcruxio

Yes and? Were we not discussing strength? Now it's suddenly frame weight. You can do things with aluminum you can't do with steel. You can do stuff with carbon fiber you can't do with steel. None of that is new. But steel is still stronger than aluminum. Yet strength isn't everything or we'd be making frames out of UHMWPE.

Originally Posted by elcruxio

You can probably buy a burned oxidized titanium frame from basic alloy that doesn't beat 953 in terms of strength to weight. I'd imagine the better vacuum welded stuff is a bit more expensive.

Originally Posted by tomato coupe

"To date" and "to that date" have different meanings. You can claim you made a typo, but you can't claim what you wrote means something else. And, since the Antonov no longer exists, it is not "the biggest airplane now."


There are ways to deal with soft materials in structural applications, such as threaded inserts. Regardless, we can choose another material, such as oak. It has a specific strength nearly identical to aluminium and is very hard. Or we can choose nylon, which has a specific strength greater than stainless steel and nearly (90%) the same as titanium. Yet, neither oak or nylon are used for construction of bike frames because they lack adequate tensile strength.

The bottom line is that specific strength does not determine if a material is suitable for bike frames. Why are you fixated on it?

Originally Posted by Kontact

Well, no. We were discussing how materials with high specific strength are necessary to make light frames. In fact, you said:



There isn't any Ti bike that was welded without shielding. Your post implied that there were. The welds wouldn't even take.

Originally Posted by elcruxio

You're going to have to be a bit more specific in your posts. I had strength to weight in mind, not the weight of frames.

This is all so confusing. You've started probably a dozen topics in this thread alone, in all of which you must have the last word be it wood construction or airplane design. And when you're wrong you shift the goalposts.

Anyways, like I mentioned earlier, aluminum nor pine cannot beat steel in strength to weight. But if we're discussing extra light bike frames, aluminum has some other ways to bypass pure strength to weight. In the end however even aluminum can't beat carbon fiber. However the carbon frame needs to be laid out properly so it gets the same stiffness as an aluminum frame of the same weight.

Originally Posted by Kontact

I imagine the problem with nylon is the same problem with kevlar - too flexible. Kevlar is incredibly strong, but not stiff. So we don't use it alone for structural composites. Both are used to make ballistic cloth that is flexible enough to absorb impacts without tearing. Something that carbon or fiberglass are too rigid to do.

Originally Posted by Kontact

Steel was only used to point out that Indurain beat people riding lighter carbon and titanium in races that were friendly enough to climbers that at least one placed second to him.


The peloton rides what they are sponsored to ride. So no Croce, Chorus, Sante, Ultegra, Force, Sprint, etc. Doesn't matter how good the components are - the top level ones are better advertising for the sponsor.


My point is that you don't need a $14000 bike to be competitive in the pro peloton. Up until last year almost everything was won on cable brakes. Electronic shifting doesn't make you faster. Making minimum weight (if that's even necessary) can be accomplished with fairly ordinary materials and component choices. Sram Force mechanical on 2.5 pound frame will get you there without too much effort and cost less than $5000. So why are we discussing uber expensive bikes as if they are racing necessities?

Originally Posted by Kontact

I feel sorry for you, so confused by the things you read.

I imagine the problem with nylon is the same problem with kevlar - too flexible. Kevlar is incredibly strong, but not stiff. So we don't use it alone for structural composites. Both are used to make ballistic cloth that is flexible enough to absorb impacts without tearing. Something that carbon or fiberglass are too rigid to do.

Here's a hard wood frame from Renovo (ash and gum cherry). They weigh around 5 pounds and have nice ride characteristics. Would you say it is not made of wood?



Here's an oak one (I'm told you can't make a bike from oak):



As you know, tubular rims used to be made of wood. You can buy new ones from Wheel Fanatyk. They weigh 430 grams each.




I'm excited to see how you put a spin on this information.

Originally Posted by PeteHski

This is a stupid argument. The Pro-Peloton are always going to ride state-of-the-art bikes with all the marginal gains possible. Who actually said they were a racing necessity? They are certainly a racing preference.