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I bought a flat carbon handlebar from Hong Kong, unbranded, at ebay. I've paid about AUD25...

I wonder, will it break? How can I tell whether the built quality is OK?

It is for a road bike that I mostly use for commuting, so a bit of bunny hopping.

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    It might, it might not. Some people think that cheap CF are more prone to failure. If it doesn't have any visual defects like delamination or cracks, then I'd guess the only sure way to know the quality is a lab test by a competent person, but that beats the purpose of a cheap part. – Klaster_1 Apr 1 '16 at 2:14
  • Everything will break at some point. Question is whether your riding style will break it, or a minor accident will break/damage it for a later break. Only time will tell. So, when you do your bike maintenance, add an item to the checklist of checking the carbon parts over for cracks or chips. You might need to undo bartape or remove grips for a good look, so make this a three-monthly check, and a visual check every month. – Criggie Apr 1 '16 at 3:06
  • I changed bonny to bunny because that's what the world calls it. If its not right, please use revert then expand the answer. – Criggie Apr 1 '16 at 3:09
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    I read this article a few months back. It essentially backs up the existing answers of "it depends" and "maybe you got lucky". bicycling.com/bikes-gear/components/… – Ross Apr 1 '16 at 13:41
  • @Ross that's a scary read. yep, poorly engineering carbon parts break. Don't buy a cheap copy unless you're willing to have it break, and break at the time it's under most stress. Mind you, I feel much the same about any carbon fibre stuff. – Móż Apr 2 '16 at 5:48
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Generally quality costs money. Especially with CF, where it's not easy to tell once the product is finished. What counts is the care and attention to detail during manufacture, and the quality of the materials. You will only know whether the epoxy was properly cured when it breaks (or doesn't), and whether it was stored properly and so on. The design is also important, it's really easy to skimp on materials or get the layup wrong in key places, and if you don't destructively test a bunch of them you'll never know.

What you really hope is that you have bought an unbranded off-market handlebar made in the same factory as the real thing, and that yours is one of the ones where they used excess/leftover proper materials at the end of a run. If you're really lucky they did well on QC one day and you have an actual genuine, made-to-spec name brand handlebar, just without the branding because the order was for 100, they made 110, and all of them passed QC... so they quietly sold the extras on eBay.

If you're not lucky, of course, what you have is where someone bought the real thing, made a mould from it, bought some cheap "carbon fibre" and epoxy, taught themselves to lay it up so it looks like the real thing, and is selling them for not much more than the cost of materials. If you're extra unlucky someone saw the idea, made a mould that looks similar, lays it up so it looks about right where the customer can see it, and will have vanished by the time you discover that it's junk.

  • Totally correct - there's also different grades of carbon fibre too, "High Modulus" which has stiffer and thinner and more costly fibres for critical areas like headsets. There's the density of the sheet, how many threads/strands per inch, and there's the layup, making sure the unidirectional strands run in the direction required, and that the next layer goes the other way. Its not simple stuff, this carbon fibre. – Criggie Apr 1 '16 at 6:14
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Maybe.

A lot of (all?) pricey carbon stuff is made is made in the far east, and much of it in the same factories with the same moulds.

What you're paying for is accountability really. When you buy a pricey carbon widget you're moving the responsibility of making sure it's ok from you and onto them.

Any company with a valuable reputation is certain to have invested at least some time and effort into design, testing, insurance, etc.

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    You see "made in the same moulds" a lot with these cheap CF parts. It means nothing. The CF layup process is what gives CF is strength. Which way the fibers ar layed, how many layers, etc. Much of the time this is the proprietary knowledge. The real question you need to ask yourself is what happens if it fails, and what are you really saving with that CF bar? Is if worth risking serious injury to save 20g off the weight of your bike? – NRiding Apr 7 '16 at 23:31

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