PeteHski

There's a lot more to it than that:-

https://www.elevatedmaterials.com/ca...y-to-use-them/

With UD you can tune the stiffness/compliance in specifc directions - which is obviously very useful in a bike frame. Woven sheets are typically used both for top and bottom of UD layups and not just for cosmetics - also for durability and for use in machined areas. Of course a single sheet of woven carbon used as a finisher isn't going to contribute much to the overall structural stiffness.

Back in the early 90s I worked for a company manufacturing Forumula 3 and Formula 3000 carbon monocoque chassis. The F3 "tubs" were typically made from woven bi-directional carbon with very little UD (which was a lot more expensive at the time). The F3000 tubs used a lot more UD and were roughly twice as stiff torsionally and about twice the cost. So it's good to see UD being used extensively in modern bike frames. It shows how much the industry has matured.

Lombard

Exactly. Frames in general are overbuilt. How many carbon frames do you see splitting apart while riding unless they already had some previously unseen crash damage?

bbattle

Yes, it would dial it up to 400 watts and drope the Hamer.

Damn, people. Carbon frames, properly taken care of, will outlast you.

Steel frames, properly taken care of, will outlast you.

Aluminum frames, properly taken care of, will outlast you.

That is the truth, end of discussion.

The comprehension of my sentences, should focus on "properly taken care of".

In other words, if you crash, the frame will often suffer damage which shortens the lifespan of said frame. How much depends upon the severity of the crash.

Testing has shown that carbon fiber frames are far, far stronger than any o'l steel, aluminum, titanium, wood frame.

But if you slam your bike into a guard rail at 30mph and smash the chain stay, you should expect some problems down the road. As I said earlier, carbon fiber layups do not like impacts.

Now, slamming a steel framed bicycle into the same guard rail at 30mph is probably going to cause equally bad news.

Now, if you disagree, that's fine. Keep riding whatever bicycle you've got because I've already stated the truism that given proper care, whatever you ride is going to outlast you.

I'm out of popcorn now; be back later for the next "will I die if I ride this bike?" thread.

Branko D

The point is to ride enough that your bikes don't outlast you but the other way around, though.

oldbobcat

I had a 2008 Giant TCR, purchased slightly used, that went saggy on me starting my third year with it. I'd heard from many that the TCRs of this era had issues and Giant was replacing these frames, no questions asked. I wish I knew. But I replaced it with a 2012 Trek Madone 5.5, partly on the basis of Trek's frame warranty, and it's still going strong.

Koyote

What does “saggy” mean in this context?

Lombard

That's a new one on me.

.

oldbobcat

From the start I could tell the bike was less stiff than the Felt F5 that it replaced. But it had a nice snap and it fit perfectly, and it was all Dura-Ace with Mavic wheels. I liked it. The decline started as getting just plain "whippy," the old-school term for a steel bike that was too big or too long for the selected materiall, mushy steering, energy-soaking sprints, and difficult to control out of the saddle. At first I thought it was just me getting out old. Then it got squirrelly. Descending, I had to stop pedaling at 35 mph just to keep it in a reasonably straight line. If there was a crosswind, my knees were clamped to the top tube. I had to borrow bikes from the shop's rental fleet to lead the Saturday group ride. I couldn't trust myself riding next to anyone. I retired the bike when I noticed that the wheelbase got longer when I sat on it.

Lombard

YIKES! I was going to say "flexy", but this goes well beyond flexy. Sounds like a crack in the frame somewhere.

thin_concrete

Yeah - absent a crack/structural damage, I can’t imagine any expansion be noticeable to the naked eye. How much was this bike flexing?

vespasianus

Except for the elongating wheelbase (eek!) and the issue in crosswinds, what you describe sounds like old wheels that need some work. How much did the wheelbase change?

oldbobcat

No, because I used the wheels with no trouble on the Madone for Ride the Rockies in 2013. As for the wheelbase, I didn't measure the spread, as I was sitting on the bike. But I observed the wheel shifting forward slightly as the seat post (27.2 mm) leaned back farther as I put weight on it. My impression was that the top tube was bowing from a leverage effect at the seat lug. And no, the seat post was not over-extended, and no, the bike was not too small for me, and no, I did not weigh over 200 lbs. And, my store manager, who raced for a Giant-sponsored team during that period, confirmed that these frames would be spent at the end of a single season, and Giant gave them new ones as needed. They rode harder than I did. And there have been similar stories from owners of some small brands from that era, like BH and Kuota. Any more questions?

Carbon fiber is a very strong material, but the resins and techniques that bind it are a mixed bag. Interestingly, when Trek started offshoring their 500-level Madones, they chose Giant as their fabricator. I've never heard of problems with Trek carbon fiber.

vespasianus

So was the thinking this was just a bad "batch" of frames that should never behave like that?

Lombard

So you have a full-suspension bike without paying for a full-suspension bike!


I've never heard of problems with Cannondale carbon fiber or for that matter, carbon fiber from most brands either. I have in fact heard of problems with Trek carbon fiber frames.

oldbobcat

Well it obviously wasn't done this way deliberately.

oldbobcat

Yeah, but there was no build-up before bottoming out.

oldbobcat

There's a series on YouTube about carbon frames, by Raoul Leuscher. He splits damaged or warrantied frames to examine how they're made. It's difficult to draw definitive conclusions from these reviews, but they show the manufacturers' attention to detail and what can possibly go wrong in fabricating a carbon frame.

tomato coupe

How old was the frame went it went flacid?

oldbobcat

Like detumescent? It was a 2008. I bought it in 2009. I started noticing changes around 2011, and by 2012 I knew it was a lost cause.

It's crossed my mind that the seller might have known the frame was defective, but when it arrived it looked flawless. It truly was hardly ridden, and it rode superbly for about two years.

tomato coupe

I thought you stated you bought it used, and that it went soft the third year you owned it. Less than a year old when you bought it?

thin_concrete

I can’t imagine Giant’s production of Trek (or any other brand’s) bikes would so be markedly different that this was a common failure for Trek bikes of that era. If there were issues, I’d think other brands would see the same issues. Maybe I’m way off though.

vespasianus

I think Giant makes about 10-30% of all carbon bikes out there. I have had "bad" carbon. A carbon seat post from Amazon but shipped from China - no name brand and dirt cheap. Was so soft that I could compress it by pressing. Whole thing felt kinda like paper mache. Lasted one ride and crumpled. Did not snap but collapsed like a wet paper towel roll.

I wonder if the Giant was a counterfeit?

Lombard

Sure sounds like it.

t2p

recall problems with early Trek carbon frames with aluminum lugs - the bikes / frames had a lot of miles though

early Trek OCLV frames were susceptible to failure from dropped chains - Trek then supplied a steel 'ring' that mounted behind the drive-side bottom bracket flange to prevent the chain from sawing through the chain stay

also heard there were some cases where the threaded bottom bracket inner 'shell' bond failed ... would spin when bottom bracket was installed

Lombard

Ahhh, so that's why my 2007 Trek Pilot 5.0 has that steel ring.