Are Carbon Frame D/H Bikes the Future?

Apr 5, 2010
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Is it just me or does it seem like carbon fibre and downhill riding don't go hand in hand. It's not that I doubt the strength of a carbon frame to absorb the intended impacts of a successful ride, it's just those unintended impacts of a not so successful ride that leave me a little dubious.

I've heard that carbon frames are actually cheaper to purchase in bulk than aluminum frames. Maybe that explains it all... better margins for the manufacturer, even with warranty replacements.

Maybe warranty issues are a red herring. Out of 10 people that buy a downhill bike, how many actually use them as intended and so run the risk of stressing the bike beyond it's limit?
 
bc_hills said:
Is it just me or does it seem like carbon fibre and downhill riding don't go hand in hand. It's not that I doubt the strength of a carbon frame to absorb the intended impacts of a successful ride, it's just those unintended impacts of a not so successful ride that leave me a little dubious.
Don't forget the sudden failure characteristics. Metal alloy frames tend not to do that. Sensible thinking on your part.

bc_hills said:
I've heard that carbon frames are actually cheaper to purchase in bulk than aluminum frames. Maybe that explains it all... better margins for the manufacturer, even with warranty replacements.

Maybe warranty issues are a red herring. Out of 10 people that buy a downhill bike, how many actually use them as intended and so run the risk of stressing the bike beyond it's limit?
Anecdotes suggest Giant's finished cost is about USD $50 ea. for 'pro' alloy frames. I don't think carbon is there yet.

Of all high-end bikes sold, a tiny percentage actually get stressed beyond doing a century or a few slow (compared to world cup times) runs a year downhill.

It's been very long since I've worked in a shop, but my friends tell me consumers have varying luck getting carbon failures replaced under warranty. The point being, most of those failures are rider initiated, not workmanship related.

Are carbon DH bikes the future? If people buy more of them than alloy frames, then the answer is 'yes.'
 
Jun 10, 2009
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They're not the past, they're (with few exceptions) not the present, and somehow I doubt they will be "the near future", at least for most riders.

In the world of road bikes, where weight is generally a greater concern than crash-worthiness, you can engineer the bike to meet structural loads while esentially ignoring impact strength.

If you actually ride DH, crashing is essentially inevitable, so the bike needs to be built to take the punishment of significant hard-edge impacts anywhere along the frame. I don't doubt that it's easily possible to build a CF DH bike as tough as any alloy frame out there, but that takes more raw material, and the raw material isn't cheap (unlike alloy).

The other factor is of course that making the frame a bit lighter doesn't actually gain much for DH riding, so why bother? Contrast that to XC racing (or recreational trail riding) where a lighter bike is (all else equal) less work than a heavier bike, and it seems logical that DH would be the last to go CF.
 
Apr 5, 2010
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dsut4392 said:
The other factor is of course that making the frame a bit lighter doesn't actually gain much for DH riding, so why bother?
Apparently a carbon frame beefed up enough for dh isn't much lighter than an alu frame. But even if it were its irrelevance wouldn't stop marketing or manufacturing. On a related note, there's no point in a sub 1000 gram road frame either (uci rules), but it does allow power taps and such to be added while keeping the bike super light. Maybe the same sort of logic would apply to carbon dh rigs... lighter frame heavier = longer travel forks (for example). After all, at some point everyone complains about a bike being too heavy (somewhere approaching 48 pounds!)

If you lurk through forums where people discuss these cf bikes as they're introduced, commentators are absolutely gobsmacked by the "look" of these cf frames. People want them and want them bad.

I find it interesting because marketing will meet reality here pretty quickly and I wonder how it will all pan out. For the moment, marketing is winning... cf is on the rise despite all the anecdotal evidence that cf dh frames break easily.
 
Jul 17, 2009
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Trek has added protection to the down tubes of their carbon MTB frames I am told because of failures. But I have no first hand proof of that.
 

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