I understand the differences in types of carbon (T700, T900, T1100 for example). Brands such as Pinarello and Bianchi tend to talk about the carbon used on their frames. However, brands like Specialized and Cervelo don't display the types of carbon used on their frames. Does anyone know what type of carbon is used on the Specialized Tarmac and Cervelo S5/R5 models?

I don't know off the top of my head, but I am sure the company websites give detailed info on that.

Specialized nomenclature is FACT 8r, 10r, 12r, etc with the higher number being higher mod CF. Really though, I wouldn't let any of this be a major factor in buying - a lot more goes in to the frame than the predominant type of CF used.

Cervelo's website does not. In fact, they have an article that basically says "don't be distracted by this stuff, pay attention to how the bike rides."

I agree with what Cervelo is saying. Unless you are replacing your bikes ever couple of years, I would steer clear of frames that advertise that they are using very high modulus CF. They are fine for riding and racing, but they tend to be very fragile.

Plus bikes use different kinds of carbon in different places.

Except I guess we don't know if eg. Cervelo is using the fragile high modulus CF or not.

The properties are designed in at lay up. The type of carbon is only one consideration, of many. Orientation, weave, resin type, all factor in to the engineers endless iterations of compromises until the design is finalized.

There is a lot too it, and it's not all even carbon fiber all the time. I know of applications where copper sheets are used, fiberglass is used, filiments of exotic metals are woven in like chicken wire to obtain a particular property of one sort or another. It's fantastic & complicated stuff. Advertizing type of this or type of that is more about catering to a chosen targeted demographic. Usually to middle to high income, tech savvy, early adoptors, or the aspiring competative minded cyclist.

It's hard to buy junk these days an CF price point. Being a proud Cervelo R5 owner, I find myself shocked when I say this, but maybe they don't elaborate on type because it really just is not important. It's the sum of it's parts and the whole intrinsic experience on that machine that you are buying.

I'd be very surprised if they weren't using very Hi-Mod CF on portions of their lightest frames. FTR, using Hi-Mod cf isn't what leads to the frame being fragile, it's that less of it is needed to get the desired stiffness.

I think the main benefit of T700, T900, T1100 is to give you upgradeitis... as you're test riding that Gan S, looking at the T700 logo just behind the stem and thinking... Hm,.. the Gan RS has T900 carbon for only $1,000 more. Same exact geometry! Different paint job, different carbon sticker behind the stem.

I successfully avoided the urge to get the fancier carbon bike because they didn't have one in my size. Phew!

GT uses fiberglass in the Hellenic chainstays of their Grade gravel road bike, because it's more flexible than carbon fiber, thus adding compliance.

Also, you're completely right about the rest of your post: the type of carbon is only one of many properties that determines how strong and light and stiff a frame is. It doesn't make sense to focus on one and ignore all the others. And since we're not privy to the whole thing and most of us don't understand how all this stuff interacts, it's better to just evaluate the frame as a frame.

Or where in the lay up it may/may not be. My guess is it wouldn't be on the surface or in any area with a high impact/high shock risk if it were even used.

How many CF failures have you seen in real life, in person that would make you question the materials properties & the engineers knowledge/design?

I've seen 2. A down tube that was cracked right across the middle. The customer said it was the bike/frame fault & thus sold a defective frame. When the return was refused, he left the store, put the bike on the roof rack & secured the rack hook directly to the center of the down tube where the crack was. Exactly the side to side load it was never designed to take. His rack was like bending a drinking straw...but it in his eyes it was Fuji's fault for making a breakable bike.

The other, some forks I over torqued with too big of a rotor. In this case it wasn't the material, I too was exceeding design in a manner not intended. Could've been steel, magnesium, aluminum. Material didn't matter.

I believe each brand has their proprietary types of carbon fiber materials. So it is hard to compare between brands. You can compare weights between different brands in terms of framesets, and that will give you an idea of the "quality" of the carbon they use. However, frame shape and design comes into it as well, so it is really comparing apples to oranges. Trek's Domane might be a lighter frame than Specialized's competitor, but it might also flex more or be more fragile, so it is hard to know what you are getting.

The only sensible thing you can compare is the different types of carbon in the same manufacturer and the same frame shape. I know Trek uses different carbon types in their frames they call OCLV 700, 400, 300. Higher numbers being stiffer and stronger for the same weight, or lighter weight for the same stiffness and strength.

I think at a certain point you have to take manufacturers at their word about how "stiff light and strong" their frames are, because they give you very little real verifiable information about them. All those materials designations are also just marketing up to a certain point.

Pretty much what he said. I agree.

The modulus of CF (T700 vs T1000) is not good, better, best. Like steel, lower modulus is tougher and more flexible while higher modulus is stronger but more brittle.

Using only high modulus CF would be like making a steel bike frame out of high carbon knife steel. Sure, it would technically be more rigid for the weight, but it would be much more fragile than the medium to low carbon steel used.


Wondering about a manufacturer's carbon is like wondering about their lay up procedure. It's really the manufacturer's business, and it is only really offered when someone is using the misunderstanding surrounding carbon modulus as marketing - which is dishonest.

It's interesting because some companies, like Bianchi and Pinarello, brag about their carbon. Other companies, such as Cervelo, offer no information whatsoever about their carbon. However, both companies claim to use the best carbon in their frames. How, then, can a consumer make an educated decision between the competing manufacturers when there is no way to compare constant variables? In other words, the implication is that attempting to compare different manufacturer's carbon is necessarily comparing apples to oranges. This makes it difficult for a consumer to be properly informed.

The last time you bought a car, did you ask for the chemistry of the metals used?

The modulus of the carbon has nothing to do with quality. You are not going to be able to tell anything useful about a frame by knowing it is 25% T700 and 75% T1000.

Evaluate bikes the way everyone else does - by its specifications, reputation and ride qualities. It could be 20% pencil shavings, but if that produces a great frame, why do you need to know about them?


Taking the opposite view, you can make an incredibly poor frame with the same materials someone else made a perfect frame out of.