Sure a tragic end for this fellow. Condolences to his loved ones and family.
While the steerer mentioned in the article was aluminum, I have recently seen two failed carbon steerers in person. The first one failed when the owner forced a conventional SFN (star-fangled nut) intended for a steel steerer into his carbon fork. Fortunately, it split immediately preventing harm while riding.
The second failure was caused when the proper/recommended expansion plug was installed with too many spacers *above* the stem. This caused the stem clamp to be sited over a non-reinforced section of the steerer and it split just below the stem itself -- again, fortunately while the bike was in the repair stand. This illustration shows the problem nicely:
http://forums.roadbikereview.com/components-wrenching/cutting-carbon-steerer-270825.html#post3761285The steerer failure looked like this:
http://www.velonews.com/2010/06/news/steered-wrong-racers-concerned-about-broken-carbon-steerer-tubes_121389Both instances were example of "operator error", but illustrate the need for correct installation, particularly when materials other than steel are used for steerers. In both these cases, the owners/installers had not read the included instructions, so were unaware they were making the installations in error.
Best,
Dan.