I’ve always wondered (and I may have even asked this on other forums with no satisfactory reply), how much difference does the quality of carbon make to a frame?

Most manufacturers offer their frames in at least 2 grades of carbon , the expensive high modulus type and a lesser grade which is usually considerably cheaper and not much heavier. As examples Specialized have their S works Fact 11 frames and the Fact 10 grade branded as Specialized. Trek has SLR and SL frames. Cannondale have their premium High Mod frames and so on.

Has anyone had direct experience of switching between the two types and can tell the difference in ride quality apart from the weight difference?

I ask because I am looking at buying an Argon 18 Krypton Pro which has received good reviews in the last two years but it is only 140 grams lighter than the lower GF model which is obviously cheaper.

On road bikes, I can absolutely feel the difference. Just go to a shop and test ride both. If you can’t feel the difference, or prefer the lower level frame, save some money and buy the cheaper one.

It can be very difficult to discern the difference between two carbon blends of the same frame, mostly because they rarely have the same components. (especially wheels and tires). The complement differences will mask any impact of the frame differences.

The weight difference is marginal, at most usually less than 200g ( ~1/2 lbs).

how much difference does the quality of carbon make to a frame

I think you’re not asking the right question… the quality of carbon matters tremendously to a frame, or any other part. What it sounds like you’re actually asking though is what difference the grade of carbon makes… which is very little apart from weight these days. The differences between OCLV 600 and OCLV 800 or between Fact 10r and Fact 12r is in how stiff and strong the fibers are, which equates to how much need be used to accomplish the same goals in terms of strength and stiffness. There used to be a pretty substantial difference in stiffness but now they’re better able to adapt the layup schedule to achieve their desired characteristics, so they just use more material and a modified schedule to achieve the same characteristics when using lower modulus carbon. The differences between OCLV 600 and OCLV 800 or between Fact 10r and Fact 12r is in how stiff and strong the fibers are, which equates to how much need be used to accomplish the same goals in terms of strength and stiffness.

Yes, that’s also what I would assume. Similar stiffness but lower weight due to thinner tubes.

As a side effect, I would expect the lighter version of a frame to be less durable, because of thinner tubes and more brittle high modulus carbon fiber.

(Also see New S-Works Crux. Oh my word...it was just a dream. - YouTube from 5:50 and Bicycle Stiffness - The Truth. Ep 2. Second Moment of area, stiffness & compliance explained. - YouTube)

As a side effect, I would expect the lighter version of a frame to be less durable, because of thinner tubes and more brittle high modulus carbon fiber.

I can’t speak specifically to the durability of the Crux in your video but that video is nonsense and that guy just has a bone to pick with Specialized… the presumably durable Santa Cruz CC spec mountain bike he references in comparison to the presumably fragile Crux uses the same high modulus carbon fibers that he’s suggesting aren’t as durable.

The idea that high modulus carbon is somehow inherently weak is just nonsense… Pinkbike’s visit to the SC test lab thoroughly disabused me of this notion a decade ago and I’ve ridden dozens of high mod carbon bikes since then without issue; road, mountain, gravel… trail bikes on DH courses, road bikes in the dirt, gravel bikes on singletrack.

As a side effect, I would expect the lighter version of a frame to be less durable, because of thinner tubes and more brittle high modulus carbon fiber

Not necessarily….there is a lot that goes into carbon technology. It is pretty complex.

If you all haven’t already seen it, CT just published a Time video showing them manufacturing a carbon frame. It’s beautiful and fascinating.

Kind of funny how much notice Time is getting for that process recently when it’s just what BMC started doing with loom manufactured tubes like 8-10 years ago.

I can’t speak specifically to the durability of the Crux in your video but that video is nonsense

Thanks for the insightful and objective response.

uses the same high modulus carbon fibers that he’s suggesting aren’t as durable

There is not just one kind of “high modulus carbon”. Only Specialized and Santa Cruz–and the factories that make their bikes–know which kind of carbon fiber they use for each part of their frames.

Different kinds of fibers (and resin) have different properties. Carbon with a higher Young’s modulus (“stiffer”) usually has lower tensile strength (“more brittle”). That is just how it is. There’s a diagram right on Toray’s web site showing this and even bike manufacturers will tell you the same thing.

How durable a certain frame is depends on many more factors, though.

Thanks for the insightful and objective response.

There is not just one kind of “high modulus carbon”.

Carbon with a higher Young’s modulus (“stiffer”) usually has lower tensile strength (“more brittle”). That is just how it is.

How durable a certain frame is depends on many more factors, though.

You just had a little fit, tried to disagree with me, and then proceeded to agree with me all in the same post… curious approach but I admire your commitment to it.

Well, Time has been doing RTM for whole bikes since I don’t know when. Here’s a factory tour from 2013: Inside Time | road.cc

Concerning the manufacturing quality you can head over to Leuscher’s youtube channel and find a BMC frame cut up and also a Time frame cut up. From a quality standpoint I would choose Time any day.

While it is theoretically possible that the frame with higher modulus thinner material is more durable than the lower end counterpart, I’d say it’s more likely that the one with more material both carbon and epoxy can normally take more of a beating. Lack of stiffness is kind of good to survive a beating. But who cares? Everyone changes bike every two years anyway, right?

It’s not something we as consumers can check in any case.

Well, Time has been doing RTM for whole bikes since I don’t know when. Here’s a factory tour from 2013: Inside Time | road.cc

Concerning the manufacturing quality you can head over to Leuscher’s youtube channel and find a BMC frame cut up and also a Time frame cut up. From a quality standpoint I would choose Time any day.

RTM is just resin transfer molding, that has nothing to do with using a loom, which BMC was the first bicycle company to do… not long after Toyota developed the technique for their LFA.

Not sure who Leusher is or why I would care about his youtube channel but you’d be just fine in terms of quality with either a BMC or a Time.

While it is theoretically possible that the frame with higher modulus thinner material is more durable than the lower end counterpart, I’d say it’s more likely that the one with more material both carbon and epoxy can normally take more of a beating. Lack of stiffness is kind of good to survive a beating.

This is almost entirely wrong… “durability” isn’t the same as “take more of a beating.” If you’re going to use your bike as a hammer, then you definitely want thicker material. If you’re going to use your bike as a bike then there’s a great many things that matter more to durability than material thickness.

Not sure if its the recent rise in popularity of the “squeeze test” mindset but bicycle durability isn’t measured by poking or smashing bits of your bike.

Not necessarily….there is a lot that goes into carbon technology. It is pretty complex.

This bit is pretty simple. High strength and intermediate modulus fibres have a strain to failure of about 2% while ultra high modulus fibres are at 1% or less. Since the energy absorbed before fracture is the area under the curve it reduces by a factor of four or more when comparing two structures of equal stiffness made with the two different materials.

There is no way of compensating for this which I why I won’t use UHM fibres*. This in turn is why I can’t get my frame weights under 1 kg but that is less important than durability to me.

Yes necessarily. High strength and intermediate modulus fibres have a strain to failure of about 2% while ultra high modulus fibres are at 1% or less. There is no way of compensating for this which I why I won’t use UHM fibres.

One: I have ridden the Specialized tarmacs in both the S-works and the standard carbon. I do think the S-works bikes ride crisper. I agree that you have to have the bikes set up the same especially the wheels and tires.

Two: I have had multiple delamination issues with the bikes as well (Specialized the company warrantied everything and were great. Again, both the S-works and the regular had issues. Both bikes were raced, travelled with etc. Standard use case which is not always pretty for a race bike.

English is not my native language, so I just now looked up durability to be sure. It says “the ability to withstand wear, pressure or damage”. I’m quite sure that most people do include the likelihood for a bike being usable after a crash or other mishap as a factor in “durability”. But sure, the ability to withstand sunlight and sweat is a factor too.

Unfortunately I won’t be able to test ride as I am only buying the frame. I’m just looking to change my 6 year old Trek Domane to something that is lighter and feels a bit faster. I’ll just be swapping the components from one frame to the other. I upgraded the wheels on the Domane a few years ago. Something like the Spec’ Aethos is no good to me as I want something that has more of an endurance geometry.

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