popeye

My wife is on a 2005 Roubaix that does ~9K + miles a year. I drilled the frame for UDI2 and with PT Boyd wheels and is still one sweet ride.

popeye

Let me take a swing at that. CF has an infinite fatigue life compared to all metal bikes which will all fail given enough cycles. I agree on repairs. Or did I miss the sarcasm? Yes I did.

Eric F 

Yeah...that's not going to happen.

Did you read the stories about the cars and planes that crashed? Have you stopped driving or flying yet?

Psimet2001 

This.

Let's be honest - if we tried to alwasy avoid all feasible risks then we would never ride bikes. Riding bikes is an inherently dangerous activity.

That said there is absolutely no ground to believe that carbon fiber represents any risk that is greater or out of line with any other material used in a bicycle.

Seattle Forrest

Carbon bikes always break for no reason.

Sy Reene

OTOH, the OP is talking about $1k CF complete bike from AliExpress or China.. not sure I'd be so confident with this set of circumstances. However, I'd be more suspect of what group/components would be put on such a beast. Empire brand shifting anyone?

https://www.aliexpress.com/item/1005001870078513.html

downhillmaster

Finally!
A refreshing new member with real life experience who is engaging in reasonable, data-backed discussion.
I am literally giddy in anticipation of him hitting enough posts to show pics.

Eric F 

This is related to the topic of carbon fiber material...

The video below is my daughter's carbon fiber softball bat ("composite" is the term they use). It started showing cracks in the barrel over a month ago (my kid hits softballs pretty damn hard). She has a goal of getting the barrel to completely separate, and has continued to hit with this bat in batting practice situations where there isn't a chance of someone else getting hurt by a flying barrel. At last night's batting practice, she hit probably 200+ balls with this bat (it's been thousands since the first cracks started to show). Surprisingly, the ball was still coming off the bat pretty well, even with the heavy damage. The severity of the cracks increased significantly during the session, but the barrel has not reached the point of complete separation due to some sections where strands of CF that have not been broken. This is the nature of CF material. Even if some strands are broken, there are others that will continue to hold the structure together.

Also keep in mind that failure of a glue joint in a multi-piece assembly is not a failure of the CF material, and may be related to human error in the manufacturing process.

This is not intended to advocate riding a bicycle that is cracked - that would be stupid.



A note about composite bats - They're pretty much designed to have a limited lifespan. Bat manufacturers are pushing the limits of performance of CF material to make the "hottest", and durability gets sacrificed in the process. Every bat manufacturer will replace a cracked composite bat within the first year of use. Long term durability is not a significant concern for composite bats the way it is for products like bicycle frames, and the materials are engineered with those factors in mind.

downhillmaster

You left out the most important part.
What does the bat weigh?

SoSmellyAir

Yes, most of the comments seem to have missed this point.

For the particular bike shown in this link, I would be more concerned with the no name brakes and the obviously fake Mavic Aksium wheels than the carbon fiber frame. My bike came with a pair of real ones; the front is not cross-laced.

Mavic Aksium Wheel | REI Co-op

Eric F 

Since you asked...23.7 oz.

burnthesheep

Lots of the fastest British TT guys that aren't "rich" run open mold Chinese TT bike framesets just fine. Lots of framesets offered from the not big name brands is an "open mold" frame they've relabeled as their bike.

As for carbon itself, you can't really weld cracks in nice alloy frames. It's done. You can repair most carbon issues like you would any composite. The fix usually stronger than original due to the added bulk of composite and resin, at the cost of weight.

If you're scared of low end import carbon, buy used. Find a local club listing and get one from a member who can chat about the bike with you.

Have fun!

Reflector Guy

The $2 off coupon tips it in for me. I MUST have one!

Psimet2001 

Nope. We haven't missed that point but its a bit like wizzing into the wind. You can't hold a material suspect based on the possibility that someone, somewhere is building something crappy with it. Especially when it has been shown to perform amazingly well when used by quality manufacturers over the last 35 or so years.

Psimet2001 

While this absolutely was the case 10+ years ago this is absolutely not the case anymore. In fact the issue with knock offs is getting worse. Major brands have been fighting it for quite a while and word was on the street that Specialized was about to unleash a can of whoop-ass on this issue.

That doesn't mean just because a carbon component is inexpensive that it's inherently dangerous or worthless... but I've seen a LOT of crap over the years. I've picked a lot of riders up off the pavement because of their awesome cheap stem, handlebars, or frames dumping them there.

It's no different than any industry - there are companies that make great stuff and some that make crap. Only in the states the ones that make crap get shut down fairly quickly as they get sued out of existence.

Used to be that old worn out molds would find their way into secondary production but all the big players now watch the molds being destroyed or take possession of them. As mold prices have dropped substantially (especially with filament wound tooling) there's little to no barrier for any brand to have their own molds. At the same time it is almost no effort for all of the counterfeit guys to simply make copies of whatever they want at any time. Many times those "open mold" look alikes are easily sold into non-US markets.

burnthesheep

Let me give an example to show what I meant, I think it came out wrong.............the PDQ V8 TT frameset is a prime example. Sold by PDQ as the "V8 TT" bike, sold by others under a different name. The bikes Gaimon hocked for a while as a sponsor were similar, it was an open mold climbing frame that the brand he was riding on procured the frames from and made bikes with them.

I wasn't meaning the $100 carbon frames folks find in the dark corners of the internet. I meant the "known good, known real" accepted open mold items.

caloso

You will be absolutely shocked what my mountain bike is made of!

SoSmellyAir

Neither the OP nor I "hold a material [i.e., carbon fiber] suspect based on the [mere] possibility that someone, somewhere is building something crappy with it." We were both discussing <$1,000 carbon fiber bikes of unknown origins. Now of course we do not have industry experience (like you do) so perhaps the $1,000 point is not the threshold between safe and unsafe. But your next post (#65) seems to reinforce, rather than contradict, this concern.

jaxgtr

, ok I will give you that.

jaxgtr

Holy crap....shipping that thing is $300 , wow.

Mojo31

Might be careful with thwith when CF tubes do break suddenly, and they do, shards will fly everywhere and they are sharp. I've seen it when CF sailboat masts fail - sharp shards fall everywhere.

Eric F 

We are aware, and plan accordingly.

Seattle Forrest

Shows what you guys know. If I can convince someone their bike isn't safe and should never be ridden, they don't want it anymore and think it has no resale value. It's a very pointy and lucrative form of trolling.

​​​​​​​Can't be ridden, not safe. The dangerous crabon probably infected the Di2, you should assume it's going to asplode too. I'll dispose of it for you and I won't even charge you for it.

@big john @LAJ we just got to the point. 🙂

MoAlpha

Yup. Aluminimum just kind of folds over. And we haven’t even begun to discuss the lightning risk!

Eric F 

I have tried a similar tactic with vintage guitars. I had similar success.