Check out this video as the triathlete on his bike demonstrates that not only can a tri bike handle the twisty roads, but it can descend faster than a car.
The videos description says:
"On a long ride through the gorgeous mountains of Mallorca's west coast we got to play a little bit with our GoPro Hero2 HD cam. The descent to the bay of Sa Calobra is without doubt one of the most stunning rides one can imagine - 680 m of elevation, countless turns and mostly good tarmac (except for a few twists) make for an incredible experience.
Actually we were pretty lucky to find only a couple of cyclists, cars and busses on the road, since it can get pretty jammed during the day, especially in spring.
The bike used was a normal Simplon Mr. T time trial/triathlon road bike with Xentis Squad 5.8 full-carbon clincher wheels and normal riding position (serious drop and forward shifted position, that is). A road bike with a more balanced position is probably even faster, but we're quite happy with the results."