Pinkbike's soon-to-be infamous video of carbon vs aluminium frames in the Santa Cruz labs:
http://www.pinkbike.com/news/santa-cruz-bicycles-test-lab.html
Carbon is a marvellous thing. It has the potential to be light, extremely stiff, and all that in fantastic shapes that simply can't be achieved with metal. Contrast that with aluminium, which is also light and extremely stiff, but can only make
some shapes and those are slightly less fantastic (hydroformed alloy tubes look cool - I'm not 100% convinced that they're the best thing ever, as the distribution of metal can be unpredictable, your thin bits end up with thick walls, and the thick bits end up with thinner walls).
But I still have one reservation about using carbon parts on a bike designed for off road abuse - quality control. Just by looking at the outside of a frame you have no real idea about whether its been well designed, in terms of where the strength is, and whether it has been well made; the quality of the carbon cloth and resins that were used, have the pivot points for moving parts been bonded to the carbon properly, are the fibres all in the right direction to extract maximum strength from the material. In the competitively priced bike industry,
especially at the cheaper end of the scale, that's a lot of unknowns. You could say similar things about aluminium but basically, its down to the tube's source and the weld quality: if your bike uses Easton tubes, that's one bit sorted, and the weld quality is practically a non-issue these days (who buys bikes based on weld quality, other than Orange customers, and people who aren't buying Commencals?).
Now its fairly clear that Santa Cruz take their QC seriously - the video is testament to that. It's pretty clear their frames will handle an enormous amount of abuse.
But I'm still waiting on the video that shows sharp rock impact tests on a carbon frame. Its far easier to bang a small hole in the side of a carbon tube, than it is to buckle the tube. And once you have that hole, the tube's integrity is compromised. Effectively ending the frames life. Aluminium, by contrast, well, you'll have a dent. Not the end of the world although a bit of a pisser if you like your bike to stay nice and shiny.
Personally, I am still a little scared by the possibility of carbon parts failing and leaving lethal sharp edges. I can't see the value for MTBs (with the exception of high priced flyweight XC bikes ridden by whippets). The cost/benefit just isn't there. You drop a bit of weight, sure, but for the average rider, is that
really an issue? The land of MTB doesn't really care about aerodynamics; unlike road bikes, which are a whole different thing - carbon rims and frames are de facto for the aerodynamic benefits. But for a recreational MTB rider, to my mind aluminium for MTBs
is just cheaper and as effective.
For sure, cheap aluminium can go wrong. Commencal's problems in 2009 are a well documented example.
But my hat still hangs on the aluminium hook. At least when I'm riding a MTB.
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