Carbon fibre is not correct material for bicycle rims?
I know there are some keen bicyclists who are fans of Danny's mcskill.
https://www.youtube.com/watch?v=VfjjiHGuHoc
I've got some carbon rims on my mountain bike. I cracked one of them coming up short on a jump with a square edged rock in it. Since then
i've been incredibly impressed with it's durability. I drilled the ends of the cracks to stop them propagating and have since ridden on it
for about 7/8 days of downhill/freeride including a couple of days in the Alps where it got a good thrashing. The crack hasn't propagated any
more and it has remained dead true.
Carbon rims definitely aren't as fragile as the naysayers make out! I will replace mine when I get round to it though!
[Edited on 28/10/17 by OliilO]
I have them on my road bike. Best wheels I've had. And with the state of some roads round here, it is just like mountain biking sometimes.
Knowing people who've suffered snapped handlebars and broken mtb rear subframes (one was a complete knob who bragged about the cost of his bike
on it's first outing when frame snapped), and being a bit overweight, I'll stick to aloominum - it has quie a bit of give before anything
breaks 
I managed to drive into local car park with road bike on roof and low barrier and apart from bent wheel and minor clamp damage to frame all was good.
Oh yeah and knackering roof bars and denting roof!
Keen cyclist and indeed a Danny MacAskill fan - his trials type cycling is quite something to watch.
Whilst I have a steel MTB and a steel road bike (both with alloy rims) I'm not against carbon fibre. If designed, manufactured and used
correctly it seems to offer some good benefits. That said CF failure seems to be more catastrophic than metal failure. Metal seems to bend/deform
whereas CF seems to snap/shatter. Not all failure methods will be the same though and I'm sure if wheel rims are designed and made well
they're robust enough.
As it stands I don't really have the money to outlay on CF cycle parts, but then my cycling isn't really top notch either