Good sources of information on carbon fiber

[hampco]

Mark, some thoughts from one who has dabbled in carbon frames:

A good source is Brent Strong’s “Fundamentals of Composites Manufacturing”.

Another way to look at your concern might be: is this structure (the down tube) designed to take this particular stress (a clamping force)? We know that carbon tubes, or structures, can be designed to counter any number of stresses: in compression, in elongation, in torsion, all depending on the intended use of the structure, generally by orientation of the fibers, quality of carbon, and number of plies. I would also submit that the engineers at Specialized are both smart people and cyclists, and as cyclists they know how bicycles are transported, something a “mere” engineer may not know.

But without knowing the exact composition of the down tube, and without knowing how much is enough, it’s tough to make an educated decision so one is left relying on the manufacturer's skill and judgement.

[Mike Lopez]

Hi Bob,

I never met Geoff but until this past year my company had been building all the necks for Modulus.

Their original process was done in an autoclave and required extensive post cure machining, (lots of labor), but I converted it to a closed mold net process that allowed them to simply scuff up the mating surfaces prior to bonding on the t-bar and fret board etc. You can see examples of this on the old Action Composites website.

Since I sold that company and moved into space junk I'm transferring all of that tech back to Modulus and the parts will be made by Joe Perman who's the maestro who's been doing fine work for Modulus for many years.

Cheers,

Mike

[Mark Davison]

Originally Posted by Mike Lopez

If there are any specific, objective, questions you may have I can try to help answer.

So here is the specific question:

I am considering in the future having a titanium frame built to replace the CFRP frame of the Diverge, but using a CFRP fork: specifically an Enve Adventure fork. This fork has clearance for large tires and attachments for fenders and low rider racks. A chip allows selectable fork offset. At the 55mm setting you can reproduce classic road touring geometries.

How would a lowly consumer find out if the Enve Adventure fork has been built to be sufficiently robust?

So I have not abandoned using CFRP components, and I have used a CFRP fork on my Trek Soho town bike for years.

[Mark McM]

Originally Posted by Mark Davison

How would a lowly consumer find out if the Enve Adventure fork has been built to be sufficiently robust?

The first place to start is to find out what standards the fork has been certified to. In the US, bicycles fall under the CPSC regulations, and in Europe bicycles fall under the EN ISO 4210 standards. The ISO 4210 standard is probably more comprehensive, and has different testing limits for different categories of bikes. For an Adventure fork, you'd probably want it to be tested in the Mountain Bike category.

The standardized tests are not always the end-all be-all of bicycle robustness, but they are a good place to start.

[hampco]

Originally Posted by Mark Davison

How would a lowly consumer find out if the Enve Adventure fork has been built to be sufficiently robust?

I’d say that a) Enve has built thousands of forks over the years and they don’t seem to fail, and b) I have sold hundreds of them over the years and have never had an issue. And heck, you could pick up the phone and have a chat with someone there - I think I’d start with Fred Mackay at 801-476-3363 and ask him some questions.

[Mark Davison]

Thanks all for the replies and concrete suggestions. I looked at the CPSC online recall database and Enve has one recall in the system.

[nmrt]

shoot...i'm made of carbon too. and am pretty sure i'll be getting a "recall" in a few decades too.

sorry that i did not have anything productive to add as MarkM pretty much covered it.

Originally Posted by Mark Davison

Thanks all for the replies and concrete suggestions. I looked at the CPSC online recall database and Enve has one recall in the system.

[tellyho]

To pile on, I think if you're skeptical of arguably the leading manufacturer (Enve) of a product, nothing we say here is going to change your mind and there is likely no data out there that will do the same.

[saab2000]

Bicycles made of metal fail as well. There is no such thing as absolute safety.

We take on risk all the time and carbon fiber (or CFRP) bicycles have been in regular use now for decades. I’m confident enough in my Look 585 (which has been damaged on a chain stay and repaired) that I actually rode it today.

[Mark Davison]

Originally Posted by tellyho

To pile on, I think if you're skeptical of arguably the leading manufacturer (Enve) of a product, nothing we say here is going to change your mind and there is likely no data out there that will do the same.

I didn't used to be skeptical of Boeing, which used to be the leading manufacturer of airliners. There used to be a saying "If it's not Boeing, I'm not going." It's sounds so quaint nowadays.

My intuition is that Enve is a good bet. But companies can clearly lose their "safety culture," which seems to come down to the ability of engineering to overrule marketing on safety issues.

[saab2000]

Xxxxxxxxx

Once again. I don’t wish to get banned!

[KonaSS]

Who is going to build that titanium frame? What sort of certifications have they passed? What specific testing has been done on their work? Is your specific frame going to be tested before you receive it?

There is so much research you need to be doing.

[Mark Davison]

Probably Brad Bingham, going on reputation and personal recommendations. His work certainly looks fanatically careful.

The research you sarcastically suggest is, as you no doubt know, nearly impossible to conduct.

I'll search CPSC recalls and this forum for any feedback on cheaper suppliers, such as Linskey in the US and Waltly in China.

The repeated Boeing fiascos have definitely shattered my general trust that corporations will engineer their products with the safety of the public in mind.

[Carbonita]

Another consideration is that (isotropic) metals generally, but not always, have failure modes that are obvious by inspection. Elongation, dents, fatigue cracks, etc. Anisotropic CFRP can fail suddenly, though some makers are using tough (as in area under stress strain curve) fabric plies to mitigate (e.g., dyneema). Perhaps periodic inspection of the bike is underrated. I'm that guy in the group ride reminding us to inspect our CFRP fork steerers annually for damage. The trend for internal routing of hoses has made this task more difficult though.

[jamesdak]

It sounds like the OP just needs to be honest with himself and not deal with C.F.

If your fears of something are so overwhelming as to lead you down this path then why even bother? Not trying to be mean just realistic.

I mean I"m the "steal is real" guy who loves to crack jokes about C.F. randomly "asploding" but I know that just isn't reality.

I mainly ride used bikes made from all materials and know little of the history of any of them. This includes my C.F. bikes and forks that go back at least to the early 90's. I'll hammer on them just as much as my steel bikes and don't really treat them any different. Heck, I had the RD body on my 2010 Madone 4.5 break one day, get in the spokes, and then rotate through the seat stay on the bike totally shattering it. I called for a ride but I bet I could have ridden that frame home if the drivetrain wasn't such a mess.