Velo Vol 

In another thread a few posters commented on the expense of "high quality" or "good" carbon fiber. I'm wondering what the characteristics or qualities of these are, in contrast to "cheap" or "low quality" carbon fiber. And what's the difference in price?

While bike shopping earlier this year, I was under the impression that while the carbon fiber frames used by the major manufacturers (e.g., Trek, Specialized, Giant) may not equal the ride of a high-end bike, they are all of a fairly good quality. Is this correct?

sydney

I don't know of any of the lower $$ ones that are particular candidates for landfill material. With Trek,Specialized,Giant, you get good technology with bang for the buck. The bigger step down is to Supergo and other generic stuff,and there are few if any gripes there either.

ehammarlund

Design costs money: deciding how to orient the fibers, how thick to make each piece, etc.
Building also costs money. The more exact you need to be in your assembly process, the moe complex the assembly, the more expensive it gets.

I--or you--could build a CF bike in a weekend. With no experience. But it would be either 1) heavy as hell; or 2) wobbly as hell/unsafe to ride.

I have not seen the CF frames, though I see alot of CF in the boating I do. The main difference in taht realm at least is atht the higher end stuff has better manufacturiong processes, which either results in increased stiffness, decreased weight, or both.

Most intelligent builders will sacrifice a tiny bit of weight (hard to notice) for good stuffness (easy to notice, depending on application).
Of course, it's my personal opinion that a few grams don't maike a damn bit of difference at my level, so--were I to ride CF, which I don't--I'd be happy with a 'cheap' one.

khuon

While by no means complete and it's slightly outdated, I consider Craig Calfee's technical whitepaper to present a good read for the layman looking to understand carbon fibre bicycle frames. Some of the things I consider high quality about my particular CF bike include:

• High quality CF prepregs from reputable aerospace grade CF suppliers
• Manufacturing process that ensures high levels of consistant compaction
• Molded in fittings (water bottle cage mount inserts, cablestops/downtube shifter mounts, brake bolt inserts, etc) instead of rivetted or drilled so that the CF structure is formed around them
• Proper attention to isolation of dissimilar materials to prevent galvanic corrosion and if bonding is used to secure the inserts, they should be capable of handling dissimilar expansion rates
• Seamless non-clamshell layup and curing process so there's no weakness in the structure due to seams
• Attention to layers through creative and smart use of different bias and weave direction per layer to tune the mechanical properties of each section of the structure
• Reinforced layering at critical high-stress sections
• Use of a protective cosmetic final layer and finish
• Metal reinforced inserts as needed (headtube, BB, seattube)

sydney

No doubt about some good points, but also consider the self serving nature of it.Acording to it, Trek and alot of others have been doing some questionable things for alot of years with no real issues.