9/6/14 10:16 AM

Ride up with wear, et al. ;)

While discussing the new calipers on the Roubaix to fix the heel strike on the rear. Also discussed the SL4 and how stiff it was to my surprise. The guy said that the frameset will soften in 2-3 years? And that the life use window of a carbon frame was 3-5 years. Reminds me of the Scandium Fuji I had circa 2000, 3 yr warranty. And most people felt that was a good time to get rid of them about then?

My Old Roubaix is a 2005, and it does have a cush to it the new one lacks. Was it a lot stiffer when new, dunno. And the Scott was 5-ish yrs old when I got it rolling. Although so clean one got the impression previous use may have been to the light side.

So fatigue, if in fact.. a fact, of course would have a wide window depending on weight and watts put into it over time.

Discuss?

9/6/14 10:42 AM

Browsing the subject nets the usual, arguments about it and the other guys opinion. ;)

Not sure about most, but the Roubaix I just got has a lifetime warranty on the frame. But they could be playing poker with that knowing most owners never get close to keeping that long and they are off the hook as soon as it is out of the original owner's hands.


Although I found this interesting, World Press Article and not from internet users/forum discussion.

Postscript: Carbon-fiber components actually do get softer with use. As the component flexes, the internal fibers break free of the surrounding resin and delaminate invisibly. When TOUR magazine tested carbon forks, they found that after 100,000 test cycles, some forks had lost a significant amount of their stiffness. Today, the European Union standards for fatigue resistance specify how much stiffness a carbon component may lose over the test cycle.

Link: http://janheine.wordpress.com/2012/03/15/frames-going-soft/


And some Forum here-say:
Without actual abuse, no amount of hard riding will fatigue it. When this discussion came up on the tandem forum, Craig Calfee of Calfee Design said he had recently had two different customers, each with over 130,000 miles on their Calfee carbon-fiber bikes, independently tell him that their bikes felt the same as the day they took delivery.

AND, personal experience. Friend in TN I rode with a lot had a 90s Epic Specialized road bike. He out climbed me easily, was near my weight. These had round carbon tube bonded to AL lugs. As far as know he still has it. All you had to do was look at it to see the use it endured.

So with today's technology as compared to bonded to AL lugs, is 'new tech' carbon longevity better potentially?

9/6/14 12:51 PM

I -THINK- Velonews discussed this once or more and interviewed various carbon fork and tube makers. Their responses were uniformly no, it does not fatigue or soften. Barring a catastrophic event/crash, they said the lifespan of a fork or tube was basically unlimited.

I have an 02 Calfee and I have not noticed any softening, but thats probably not a good indication as butt memory is questionable.

I suspect that the years from 2000-2010 were the best as far as carbon frames goes. Good but not excessive stiffness. They have learned how to make them too stiff for my tastes now, and I have ridden a few that ride like a brick.

9/6/14 12:56 PM

"butt memory"


glad I was finished with my coffee...

"ridden a few that ride like a brick"

I am thinking the SL4 feels like a brick with a thin elastomer [zertz?] coating. The Scott is livelier feeling albeit as stiff [stiffer?] Butt memory not withstanding, feels a lot like I remember the 5500 OCLV and like the Y-Foil did minus the cush of the beam of course.

Dead but stiff, but no woody resonance like the 5500 had, being it was like a carbon speaker and all. ;)

Anyway, made my point about that way too much probably...

9/6/14 7:13 PM

There are three failure mechanisms for a CF composite structure (same as for fiberglass composite):

1. Fiber pull out - the fibers physically separate from the epoxy matrix

2. Fiber breakage

3. Epoxy cracking (somewhat tied to the first two, as it is hard for the fibers to pull out or break unless there is "open space" generated by epoxy cracking).

As these things happen, a composite part can indeed soften. This used to be VERY common in downhill skis - sometimes they lasted only a season and they were noticeably softer. It was easy to measure the changes.

Whether this is happening in a given bike frame depends both on the frame and the service level. A very light frame that is pounded on cobbles under a heavy rider is likely to suffer while a sturdy frame under a light rider on smooth roads may last longer than anyone cares to know.

The boiler plate "frames go soft after 2-3 years" is pure nonsense, since the person making the claim cannot possibly know either the frame's properties or the service it will be put to. Remember when people believed that steel frames went soft?

While durability is the prime reason I would not get a CF frame, it is more about both minor and catastrophic impact concerns. They can chip and fray and we all have seen the pictures of crash results. A well-built Ti frame just about has to be run over by a truck before it will fail like that.

9/7/14 8:48 AM

Dude, you don't know what you're missing by not at least trying carbon fiber. ;-)

While you are absolutely correct about failure modes and potential durability issues, they're not a major concern in day-to-day riding, especially if one doesn't race and therefore has a low likelihood of crashing. Also, if you're leaning toward the comfort end of the spectrum, those bikes are generally overbuilt using more durable, but less stiff materials, rather than the ultralight, ultra-stiff, but more brittle materials used in top-end race machines. Also, bear in mind that composite are repairable to a pretty extraordinary degree.

That said, the relatively minor risk of damage is a small price to pay for the major gains in performance across the board. It really is pretty dramatic. I've been riding carbon fiber bikes off-and-on since 1977 and have seen their somewhat slow, but incredible evolution since then. When carbon fiber was in its infancy and lacked sufficient stiffness for racing (imagine that!), I chose aluminum fat tubes instead. When CF became more functional, but offered little benefit, I tried it, but switched to Ti for its durability, superior ride and ease of maintenance. Now that CF technology is mature and has well documented advantages in nearly all respects, I've gone back to it again, probably for good this time. Seriously, you owe it to yourself to check it out.

Getting back to the original question, the person who told Sparky that the bike would soften in 2-3 years is an idiot (or grossly misinformed) and I would not take advice from him. If he's a mechanic and/or salesman at the shop, report this misinformation to the owner so he can retrain this guy before he misinforms more customers. If he IS the owner, I would not trust any technical information from him without verifying it elsewhere.

The truth is that unless you stress carbon fiber beyond it's yield point, it will last indefinitely. Remember, they build aircraft wings and control surfaces with it and they flex a lot. It's all about knowing the expected loads and building the structure to exceed them by a comfortable margin. I have full confidence that the major bike manufacturers are doing this very well, and in the rare cases where they do find issues, they recall the parts and replace them with improved versions (I don't recall any issues with frames, but there have been some with forks in the past). However, I would steer clear of the generic Chinese frames, as there is no way to determine their pedigree, the materials used or their construction quality. Some my be excellent, but there a numerous horror stories about junk frames and forks.

9/7/14 9:09 AM

I agree with Brian although he says things much better than I ever could. Besides, I buy frames for how they ride, not how they crash, as I don't plan to crash :)

All this said, I just bought a ti frame as I like it as a material, but I don't have great performance expectations for it.

Brians 585 is one of the most liked frames on the planet:people just rave about them,and if I still road biked, I would seek one out.

9/7/14 6:33 PM

Both Brian and Kerry are correct.

What Kerry experienced with skis was likely the failure of the core/laminate interface or softening of the core itself, as pure cf skis didn't really exist.

I've been on carbon, on and off, since Graftek in the mid 90's. The change over time has been the reduction in the amount of material and consequentially the amount of resin. Resin feels dead. An early carbon frame felt like a large piece of wood, a modern frame feels like a stiff golf club shaft. Neither fatigue. And neither have the resilience of a good metal frame, be it ti or steel. Carbon reduces road buzz, is more "stiff" if that's either necessary or desirable, and in current 1 1/8x 1 1/2 steerer configuration ridiculously precise and hard on the wrists and hands.

But no, it never fatigues. It does break in half when you fall on it, another topic entirely.

9/7/14 6:49 PM

There may well be something to large rider/frame inherently seeming less stiff, yes.no?

I think technology has probably gotten better regarding carbon frames size designs to compensate. At least I see suggestions of this in the print, and the head-tubes/forks on the SL4s which I am recently more versed on.

Specialized for example using 1-1/8: HTs on the 54s and smaller, and two steps of tapered Head tube and size specific designs on the forks. SL4s anyway, Tarmac and Roubaix as far as I know [think I know].

The 58 Roubaix I just bought is 1-1/8" to 1-3/8" for example. I think the middle size is a 1-1/8 to 1-1/4" going from memory. [such as it is].

And I believe also the upper level frames, unless thay are just talking the headtube difference.

9/7/14 7:13 PM

quote:

---

There may well be something to large rider/frame inherently seeming less stiff, yes.no?

---

9/7/14 7:38 PM

Spesh web examples:

frames tapers from 1-1/8” at the top to 1-1/2”, 1-3/8”, or 1-1/4” at the crown—depending on frame size

Size-specific tube diameters, seatstay angles, and carbon fiber layup change as you go up in frame size.

But I think I read the layup changes are not on the base model frames, but tube size changes are.


Exactly along the lines as what you indicated K..

9/8/14 5:33 AM

Skis are a sandwich, with a core material separating top and bottom layers of composite materials. Flexing of a ski creates shear stresses within the sandwich and when the stress exceeds the strength of the bond between layers, the layers start to delaminate and the ski gets soft.

Bike frame stresses are more in torsion and flexion and there is no core in a tube, so the same type of delamination is unlikely. I think it's fair to say that most failures in carbon frames are from either direct impacts with another object or severe road impacts that overstress and fracture the structure.

9/8/14 7:02 PM

quote:

---

Skis are a sandwich, with a core material separating top and bottom layers of composite materials. Flexing of a ski creates shear stresses within the sandwich and when the stress exceeds the strength of the bond between layers, the layers start to delaminate and the ski gets soft.

---

9/8/14 10:18 PM

I was talking to a good skier yesterday - he spends six months of the year at Whistler as a ski instructor, three months in Australia doing the same, and the other three months he cycles with our group. I asked him about fatigue of skis, and his answer was that a ski starts to go dead after about 200 days of use. He also said that his son, who is 6'4" and a good enough skier that he doesn't have to buy his ski equipment, rarely goes through a season without having a ski break on him during use.

9/9/14 5:35 AM

...could probably say the same thing about bike frames and perhaps other components such as wheels, but we're talking about people who routinely push their equipment to the limit and beyond. That's probably not all that relevant to us mere mortals.

9/9/14 6:41 AM

I disagree. There are plenty of overweight cyclists who routinely stress their bikes as much as any skinny pro does.

I agree that carbon skis and laminates with a foam core could break down. Plus the sine wave on a flexing ski is exponentially more that any bike frame would ever see. I would never ride a bike that flexed as much as a ski and nor would anyone on this forum.

The only thing the two products share is the carbon.

9/9/14 7:41 AM

Carbon bikes and skis have been around a while. Good discussion here.

What really interests me is how will carbon fiber hold up for commercial airliners. How is the production and viability of the Boeing 787 Dreamliner holding up?

9/9/14 10:22 AM

Pro roadies in general are small, lightweight riders compared to the general population. I suspect hitting a pothole is more stressful to a frame/fork than pedaling loads would be. Except for track riders, who put out way more watts than road sprinters and may be much bigger/heavier.

So Sparky it seems the consensus is that your frame is not gonna soften up.

9/9/14 10:47 AM

the big new thing about the 787 is for the airlines that operate them: what are they like to live with and maintain. basically, how well do they handle the rough handling a bus with wings experiences during its 20-30 year life span.

for a mostly CF bird like a 787, airlines are particularly interested in:
- damage from incidental impacts from ham-fisted ground crews/equipment.
- ability to deal with lightning strikes.
- repair-ability from above.

structurally a 787 is stronger than any comparable alloy tube-and-wing passenger hauler, especially for the same weight. that oughta sound familiar to you bike nuts, eh?! i havent yet heard any pilots saying anything like "its laterally stiffer but vertically more compliant" -- i suspect it should feel different, but modern commercial planes are fly-by-wire so responsiveness is all in the hands of the programmers anymore and feel (if any exists) is synthetic.

9/9/14 11:35 AM

Really good discussion here in this thread, almost hard to believe this is "the internet"!

So yeah, as I see it, today's carbon frames, and a lot of yesterday's carbon frames too, are not going to show any deterioration unless really overloaded such as wheel-damaging impacts to a pothole perhaps, and even then it would be an exception.
I recently bought a 10-yr-old Orbea Orca that's worn through it's first rim sidewalls here in the dry west-coastal area, but I can't tell by riding it that it isn't brand new.

Anecdotally, I am aware of bearing fitment problems in certain carbon frames, so threaded-together bottom brackets have apparently been designed to deal with this.
And of course carbon dropouts can get chewed up under certain conditions of particular hub used and quick-release tightness.
Also I have seen many examples of "bruises" and stress cracks in carbon frames, from abuse, which left the owner unsure of the frame's structural integrity going forward.
However, I believe that for the most part today's frames/forks are considerably stronger on average than in the past, due to the cold realization that a good percentage of hard-riding buyers are on the quite-heavy side.
The mountain-bike side of the market also testifies to the potential toughness and durability of properly-designed carbon frames, just as it testifies to the durability of ever-narrower drive chains and carbon rims.

9/9/14 11:45 AM

is the industry following the initial Aluminum frame methodology of over building?

Sure seems like that with the SL4 I got recently.

Which I am not riding waiting on the new brakes to arrive. ;)

9/9/14 12:35 PM

Well I wrenched an airplane that has tons of carbon. They have been pulling 9gs in F16s for a bazzilion years.

I have never seen a carbon structure fail on an F16 but I have seen plenty of Al failures. The stabs, leading edges, vertical tail, rudder, flaperons, and even engine parts are carbon. They hold up fine unless the get fragged or hit with a hammer. All the large structures have a honeycomb core which is very different from a bike or the foam in a ski.

Carbon airliners will be good to go. I would fly in one with no issues 25 years from now.

9/9/14 12:58 PM

25 years? Why not now? Is it cost?

9/9/14 4:30 PM

I think Erik means he would happily fly in a 25-year old CF airliner.

9/9/14 5:27 PM

correct