Apparently, triathletes' bikes are usually unrestricted in weight, and are not governed by the UCI rules.

Yet they often seem to hover around the same weight as the TDF riders' bikes. Some of the exceptionally light ones go lower, but not often much lower.

The lightest production bikes appear to be 11.4 pounds, and the frames are titanium, with a twenty-five year warranty. They are made by Everti,

http://www.bikerumor.com/2009/04/22/...ion-road-bike/