spectastic

Where does it lie in the stiffness category compared to full carbon fiber, plastic, and everything in between?

Bob Dopolina 

Application?

Lots of saddles use carbon reinforced nylon for their base. That stuff is pretty soft but the carbon content is low and it's used in a way that wouldn't be appropriate for other applications.

Need more info.

bikerjp

Judging by the avatar, some sort of weapon would be my guess.

spectastic

the soles of these shoes https://www.nashbar.com/bikes/Produc...96_-1___202526

it says carbon fiber. but it's obviously a blend, not a weave. And I looked it up on the manufacturer catalog, which says the soles are actually a carbon-nylon blend.

Bob Dopolina 

Ok.

That's when the toss some carbon fibers into the mix and then mold as usual (injection mold?). It's supposed to add stiffness and some strength. It's possible, I suppose, but I've never seen data (and honestly, I've never looked).

That brand is a pretty established shoe and pedal maker in Taiwan. They've been at it since 1993 and have global distribution. Chances are the shoes are pretty good as long as they fit your feet.

spectastic

ok. I was a little worried, because in the picture, the sole looks a lot like plastic. It's really hard to judge its quality if you don't have the ratios of carbon they actually put in.

And I don't know how injection molding of carbon really works. Is it carbon fibers they're injecting and curing, or is it just graphite? Obviously, it's nothing like the weaves you see in most cf stuff, which they literally layer on top of each other and then soak it in some curing agent. This one, you just inject it into a mold... Can you really categorize them in the same group?

Bob Dopolina 

^^^ Different application of a material.

My understanding is that the carbon (strands?) are mixed with plastics and then injection molded.

Laying up carbon requires using the material in a different way which is strands woven into fabric and infused with resin to make prepreg which is then cut, laid up in a mold and baked. This is what most people are familiar with.

Bob Dopolina 

qft

Campag4life

Carbon fiber has greater yield strength because strands are continous versus short carbon filaments injection molded into nylon.
Glass filled nylon is a common engineered plastic. In engineered plastics, glass filament diameter and length is adjusted to gain the material strength and flex desired. Nylon inherently has not only a low modulus of elasticity (its flexible) but low yield strength.
Glass or carbon combined with nylon increases both properties.
Carbon fiber soles popular on many high end shoes will be more rigid, stronger and lighter.

spectastic

I figured... But how do they compare? going back to the first question, where would carbon-nylon composite fall in terms of stiffness with respect to weaved cf, and average plastic? Would you say they fall somewhere in between high grade cf and nylon/fiberglass blend? If so, by what margins?

also, it would make sense to me to put something elastic into the soles (like a plasticizer), to make sure it doesn't crack or anything - more reason to believe that what we're talking about is more like layered graphite than real carbon fiber. Nevertheless, if it's strong and not too heavy, I don't really care about the chemistry. But I just don't want to be fooled by false marketing.

redlude97

nothing wrong with carbon infused nylon. Where it lies in the strength/stiffness dept depends on a number of factors including %, thickness and design. Generally it will be heavier than a carbon fiber layup but it can be stiffer also if it is significantly thicker than the carbon.

georges1

the strongest carbon frames are the ones made of t900 carbon fibre along with nomex (nylon specific derivative used in the bike industry). Carbon makes a bicycle ride very light and yet very resisting to shocks. Comfort however is relative, you can't compare it to a steel or a titanium frame.

spectastic

of course you fool. damn! now my plan is ruined!!

terrymorse 

Comfort (roughly) equals compliance, and carbon is the ideal material for designing in compliance where you want it, and stiffness where you need it. Adjust the lay up, select different fibers, change the cross section shape of the tubing, etc. Not very easy to do with steel or Ti. In the hands of a good designer, carbon can be used to produce just about any desired ride characteristic.

georges1

I am pretty sure you heard about the reynolds 953 super steel or the mar aging steel which was used by carpenter technologies for building missiles. A 953 frame according to some frame builders is superior to aluminium and even carbon. A well made 953 frame is very very expensive (often costs over 2500-3000$ sometimes more). Of course we can speak about Serotta custom made carbon frames and Cannondale carbon frames that can be expensive too, but not every bike brand knows how to make comfy carbon frames.

spectastic

are you talking about that sht they use to build lightweight aircraft? I think a bike made from that material costs in excess of $14k. Something like that belongs on a shelf...not the road

rebel1916

Tee hee hee. Dude, your lack of knowledge is showing. Seriously, everyone can see it.

georges1

Read about the 953 before saying that I lack knowledge. https://reynoldstechnology.biz/faqs/materials/1

What is the background on Reynolds 953? [+]
Material - a maraging stainless steel, specially manufactured for Reynolds by Carpenter Specialty Alloys, USA. This material undergoes a double vacuum remelt process to get achieve the necessary properties and purity. It has a very low carbon content, which has an advantage that machinability compared to e.g. AerMet 100, which is improved due to low carbide content.

• Made from cold-rolled strip steel into a tube with a highly homogenous weld, done in an inert atmosphere (specialist aerospace weld mill). The metal used is double vacuum melted by Carpenter to achieve very high purity levels that are typical of aerospace applications. Although a departure from Reynolds' preference of using seamless materials for high-end tubing, tests and cross sections of the weld area show the seam is "essentially invisible" when examined microscopically.
  
• Ultimate tensile strength - 1700 to 2050MPa depending on process and heat-treatment selected (853 airhardening steel UTS 1200-1400 MPa). Density is 7.79 gm/cc. Poissons ratio is 0.30.
  
• Yield strength 1500-1900 MPa depending on the combination of cold-working, butting, and ageing temperature. (1500 MPa is approx. twice the yield strength of Cold-worked, Stress relieved 3-2.5 titanium). At 950 F ageing temperature, yield strength should be in the 1650-1730 MPa range based on internal tests. Changing the ageing temperature can increase elongation.
  
• Stiffness Modulus (E) is 200 GPa, similar to other steel alloys. If higher stiffness is required when lighter tubes are used, advantage can be taken of the higher yield strength by using slightly oversize but thin wall tubes with a lower overall weight.

FRAME BUILD OPTIONS using 953

• Can be TIG welded with AWS ER630 wire, brass braze or silver brazed using recommended filler wires.
  
• Corrosion resistance is similar to type 410 stainless steels. In normal use, brown staining of the surface does occur due to sweat, salty roads etc if not protected/painted. The staining can be removed with "scotch-brite" or an equivalent, and trials have shown that this is a superficial stain that does not weaken the tubes.
  
• The recommended method of building is the use of pre-aged tubing, so frame builders can fabricate the frames, but assume mitre and cutting could be slow due to tube hardness. Purging whilst welding the frame is highly recommended . This would reduce possible contamination on the inner surface of the weld joints, improving corrosion resistance.
  
• Frame alignment should be carried out before ageing if needed but we do not expect jigs to be needed, as this is a relatively low temperature for steel heat-treatment.

Do I need to add more?

georges1

a good quality 953 hand brazed frame costs 3500$ and more, then if you add a top of the range transmission, top of the range wheels, top of the range fork, top the range stem and bar, the 7000-10000$ can reached easily.The most expensive carbon bikes I have seen were the colnago for ferrari and the c40 with the dura ace 25th anniversary group both priced over 15k$.

Nerull

None of that has anything to do with the ride quality, and it certainly doesn't allow you to change the material properties of each specific section of the frame.

I could go copy and paste the ad copies of every carbon frame builder on the market, if that would help. I'm sure all of them claim to be the best. And they can't be wrong.

rebel1916

Apparently the price of relatively rare and difficult to work with steel alloys means, well, I don't know what. But cut and paste.

rpenmanparker 

OP, you have to understand that both components of the two composites you are asking about contribute to the final properties. In the case of the carbon-epoxy composites like used for rims and bike frames a very stiff plastic (the crosslinked epoxy) is further stiffened and most importantly strengthened by the long carbon fibers.

The strength and stiffness of the carbon fibers is effective in the lengthwise direction of the fibers. Since the fibers are long and assembled into fabrics, the fibers can be manipulated by hand and oriented in the directions desired to create enhanced stiffness and strength in those directions. The nylon composite, however, is based on a much more flexible plastic, nylon. Also the short, chopped carbon fibers in the nylon composite can only be slightly oriented in the direction that the molten mixture flows into the injection mold. The flowing liquid nylon slightly orients the short carbon fibers in the direction of flow as it passes through the narrow orifice, the gate, into the mold cavity. Thus the enhancement of properties of the nylon is much smaller than the enhancement of properties of the expoxy resin.

So with the expoxy composite one is starting stronger and stiffer AND gaining a lot more strength and stiffness. With the nylon composite, one is starting weaker and more flexible and gaining only a little more strength and stiffness. There is no way to make nylon-carbon composite suitable for construction of bicycle frames or other structural parts like rims, bars, stems, seat posts, etc. But the carbon does lighten nylon shoe soles and other goods while strengthening and stiffening them. I truly don't know the specific numbers involved, but I suspect nylon-carbon composite is maybe about twice as stiff and strong as the same plain nylon depending upon the length of the carbon fibers and how much of them is used in the blend. The epoxy-nylon composite would be several or many fold stronger and stiffer than that. I hope this helps.

Robert

georges1

There were already threads covering the great quality of ride of a 953 frame for your information.
https://www.bikeforums.net/archive/in.../t-143207.html
https://www.bikeforums.net/archive/in.../t-384997.html
https://www.bikeforums.net/archive/in.../t-721053.html
https://www.bikeforums.net/archive/in.../t-485286.html

rebel1916

Slimrider? Is that you?

spectastic

This doesn't make sense. Do you mean epoxy-carbon weaves? And how do you figure that it's several times stronger and stiffer? that seems pretty exaggerated.