# Judging Carbon Frame Quality



## D_D (Mar 20, 2011)

How do you judge the quality of the carbon frame? Specialized gives you information such as 8r or 10r. Is there really a difference between 8r or 10r. What about brands that don't give you such information?


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## rx-79g (Sep 14, 2010)

"Quality" is an ellusive term. Does it refer to the ride, the weight, the materials used, the longevity?

One could build an absolutely beautiful bike with the finest ride characteristics out of the "lowest" carbon fiber. And one can build a disaster out of the high modulus stuff (and it seems like this happens too often).

Higher end fibers are thinner, making them lighter but more brittle. So the finished product is lighter, but either required other fibers (kevlar, boron) to make them durable, or the frame is a little on the delicate side.

Most of what you read about the fibers or weaves is just marketing - especially terms like "8r", which is just Specialized's name for something that they bought on the open market, and Trek has a different name for. The core of what makes a good bike is the design/construction.


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## D_D (Mar 20, 2011)

Obviously everyone has seen nice looking furniture that feels good but is total junk. I can evaluate furniture based on the materials and building techniques used and decide if it worth paying more for better wood and better construction. My problem is I don't know enough about a carbon frame to tell whether it is worth paying more for one frame over another. I don't believe that 8r compared to 10r is just marketing. It is a difference in the carbon. What I don't know is whether the difference is worth paying for. From what I can tell the LBS and everyone else is completely guessing and really doesn't know.


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## Dave Hickey (Jan 27, 2002)

D_D said:


> Obviously everyone has seen nice looking furniture that feels good but is total junk. I can evaluate furniture based on the materials and building techniques used and decide if it worth paying more for better wood and better construction. My problem is I don't know enough about a carbon frame to tell whether it is worth paying more for one frame over another. I don't believe that 8r compared to 10r is just marketing. It is a difference in the carbon. What I don't know is whether the difference is worth paying for. From what I can tell the LBS and everyone else is completely guessing and really doesn't know.



It's what you do with the carbon that is more important than the carbon itself. As you mentioned, there is a lot of furniture that looks great but upon closer inspection, it's junk. 

Bikes are no different.. You really need to test, inspect and ride the bike to determine if it's right for you.... In the never ending material frame debate, material is secondary to design and construction...

There is too much belief that because it's carbon, it must be better or because it's made of a certain type of carbon, it must be better... rx-79g is spot on....forget the marketing and look at the design and construction.....high end carbon might not be what you need.

At the end of the day only you can decide if the $2000 desk is better than the $500 desk... they might look similar but there is going to be shortcuts in the $500 desk... and, in the case of the $2000 desk, you might be paying for the name...

Chances are, you will never be able to tell the difference between a frame made from 8r vs 10r carbon....You might be able to tell the difference on a bike made frame 8r vs 10r because the 10r frame likely has many other upgraded components that all add up to a nicer overall bike


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## rx-79g (Sep 14, 2010)

D_D said:


> Obviously everyone has seen nice looking furniture that feels good but is total junk. I can evaluate furniture based on the materials and building techniques used and decide if it worth paying more for better wood and better construction. My problem is I don't know enough about a carbon frame to tell whether it is worth paying more for one frame over another. I don't believe that 8r compared to 10r is just marketing. It is a difference in the carbon. What I don't know is whether the difference is worth paying for. From what I can tell the LBS and everyone else is completely guessing and really doesn't know.


Maybe you didn't read my last post? 8r is a type of carbon, but there isn't really good or bad fiber, there are thinner and thicker fibers.

Which is better wood: Oak or ash? The correct answer is neither. For some uses ash is better, for others oak, and lots of times it doesn't matter.

"8r" is not an aerospace composite term. It is an in house term that may refer to a fiber, a weave, a lay up schedule or all three. Unless you know a lot about composites, AND have the 'recipe' for 8r, there is no way of comparing Specialized's 10r to Trek's OCLV. The terms themselves don't tell you anything.

Specialized will tell you that 10r is "better" than 8r. And in some ways it is - I'll bet 10r is the fiber/schedule used in their lightest bikes. Is strength-to-weight the only measure of quality? 

Ash is lighter than oak.


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## latman (Apr 24, 2004)

I don't know what "r" fefers to but it it may be the stiffness of the unidirectional carbon , which other companies call "ton" or MSI or t-XXXX( if they use toray fibre). The other thing that can be described is the outer weave (regarded as cosmetic but still useful IMO) which is either 12K (made of uni fibres),3K woven plain or 1K woven plain , I have also seen some 4K twill on a fondriest (looked stunning) and i recollect seeing some twill on a Museeuw frame. Just like steel or Aluminuim frames it is hard to judge the whole story from appearance alone.


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## rubbersoul (Mar 1, 2010)

Parlee's are supposed to be good


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## Kerry Irons (Feb 25, 2002)

*The other view*



rx-79g said:


> "Quality" is an ellusive term. Does it refer to the ride, the weight, the materials used, the longevity?
> 
> One could build an absolutely beautiful bike with the finest ride characteristics out of the "lowest" carbon fiber. And one can build a disaster out of the high modulus stuff (and it seems like this happens too often).
> 
> ...


And then there are the people who think that all frames of the same material are the same. You get this "Why should I pay $X for a frame when somebody else is selling a frame made from the same material for $X/4?"

The reality in bicycles is what it always has been: you have to go by the established reputation of the manufacturer. And unfortunately wiith the drive to make everything super light, even respected builders have made mistakes and put out crap bikes. Crap either from a durability stanpoint or a ride standpoint, or maybe even both.

Agree that there really is not much of a way to evaluate frames, particularly CF frames.


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## stevesbike (Jun 3, 2002)

the drive to make things super light probably ended up making more crap aluminum and titanium frames than carbon ones - some aluminum ultra-thin walled frames would get a ding just by looking at it and some whippy titanium frames would become death wobble machines on descents.

I don't think there's anything particularly mysterious about carbon fiber quality - the grade of the CF is essentially a measure of the density of fibers. Obviously, grade of CF is just one component of frame quality - the layup, tube shaping, resin, bladder technology, etc all play a role.


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## rx-79g (Sep 14, 2010)

stevesbike said:


> I don't think there's anything particularly mysterious about carbon fiber quality - the grade of the CF is essentially a measure of the density of fibers. Obviously, grade of CF is just one component of frame quality - the layup, tube shaping, resin, bladder technology, etc all play a role.


Realy? Metal bikes come down to dimensions, alloy and heat treat. Composites have many more variables. And manufacturers purposely obscure their process so consumers are unable to tell what they are buying.

As for the fibers themselves - different densities have different properties. That isn't quality.


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## stevesbike (Jun 3, 2002)

rx-79g said:


> Realy? Metal bikes come down to dimensions, alloy and heat treat. Composites have many more variables. And manufacturers purposely obscure their process so consumers are unable to tell what they are buying.
> 
> As for the fibers themselves - different densities have different properties. That isn't quality.


it's close enough to quality as far as frame building is concerned - since different densities (dependent on fiber diameter) mean differences in tensile modulus. Just knowing the grade of carbon fiber tells you something - e.g., a frame made of T700 Toray carbon fiber (33.4 msi/711 ksi) will use more material to achieve the same stiffness - all else being equal - as one made of T800 (42.7 msi/796ksi).


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## rx-79g (Sep 14, 2010)

stevesbike said:


> it's close enough to quality as far as frame building is concerned - since different densities (dependent on fiber diameter) mean differences in tensile modulus. Just knowing the grade of carbon fiber tells you something - e.g., a frame made of T700 Toray carbon fiber (33.4 msi/711 ksi) will use more material to achieve the same stiffness - all else being equal - as one made of T800 (42.7 msi/796ksi).


That would be true, if it were practical to make a bike out of all true high modulus carbon. But you really can't, and it isn't done because it is too brittle delicate. Going up the modulus scale means making compromises (like using lower modulus or non-carbon in the lay up), so you don't just end up with a "better", higher quality bike.


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## stevesbike (Jun 3, 2002)

rx-79g said:


> That would be true, if it were practical to make a bike out of all true high modulus carbon. But you really can't, and it isn't done because it is too brittle delicate. Going up the modulus scale means making compromises (like using lower modulus or non-carbon in the lay up), so you don't just end up with a "better", higher quality bike.


except the starting point is not true high modulus carbon (a term abused a lot in the bike industry). Probably the majority of frames are made of standard modulus CF, like Tory T700. T800 is an intermediate modulus CF. You're more likely to see T800 in a higher end frame - in terms of this thread, it's a higher quality CF for bike applications (and the grade of CF used in aerospace applications).

There are some frames made from true high modulus CF, like the Jamis Xenith SL, which is M40.


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## rx-79g (Sep 14, 2010)

stevesbike said:


> except the starting point is not true high modulus carbon (a term abused a lot in the bike industry). Probably the majority of frames are made of standard modulus CF, like Tory T700. T800 is an intermediate modulus CF. You're more likely to see T800 in a higher end frame - in terms of this thread, it's a higher quality CF for bike applications (and the grade of CF used in aerospace applications).
> 
> There are some frames made from true high modulus CF, like the Jamis Xenith SL, which is M40.


Sure, but that doesn't support your notion that the higher the modulus, the higher the quality. If that were true the best frames would be high modulus, but high modulus is rarely used. 

It is no different than selecting metals. CP ti isn't strong enough for bicycles, 6/4 is difficult to build tubes out of, but 3/2.5 is the best balance. Medium modulus carbon falls into the same sweet spot.


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## ddhartzell (Feb 25, 2009)

D_D

I do believe that there is a difference in feel and ride quality when you climb up a manufacturers "quality" level for a specific frame. While I have no scientific evidence to back this up, and will probably get smacked around on here for chiming in with no knowledge base, I would suggest you goggle different manufactures demo days and locations and go see. My lasting impression from a Giant demo day over 2 years ago was that there is a big difference in ride quality between Giants levels of carbon on the same geometry. I rode a TCR (mid level giant carbon) vs TCR advanced (highest level giant carbon) and I believe both had Ultegra. Both were/are great bikes (in my opinion) but at the time, I felt the ride quality/feel of the TCR was better. It was my first bike and I was comparing the ride quality to my C-dale mountain bike on road!!! I have been happy with my TCR but am now curious about the TCR Advanced because I want the ride quality/feel that I remember from that test ride.

While I don't think you can make a blanket statement saying certain level is better than another, for basic folks like us (no offense meant)....maybe better stated as people with no carbon fiber knowledge......there is a big difference in the ride quality of frames as you climb up a manufactures product line. I equate that to the quality of the carbon but that is not a true representation. It relies way more on build and geometry and blah blah blah........

But, at least in my small experience, better "quality" carbon from brand X will "ride" better than lower "quality" carbon from brand X. 

But you have to have a clear definition of "ride better." I want the "higher level" carbon frame because I remember it being way more responsive, had better road "feel", was quicker to respond, and seemed to just "ride" more aggressive. I initially bought the "lower level" frame because it felt stable, non-"sketchy", and a better option at the time for me. I had nothing to compare to so it was way quicker than anything I had ridden. If I was doing a century tomm, I would chose my TCR, a crit....a TCR Advanced (from the ride quality I remember).

I based all this on 2 different "levels" of carbon on two bikes with the same geometry. If you throw in a different geometry, that "lower" level of carbon may be more comfortable than the "top" level.


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## D_D (Mar 20, 2011)

Thanks for the responses. The more I read about this stuff the more I believe the manufacturer hype that there is a difference within the established manufactures in the quality of their frames. That is how they sucker people in on the cheaper frames thinking that they are getting the same thing as the more expense frame. But, I also agree with the comment that it is very difficult to compare across manufacturers.


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