I still have my 1975 Teledyne Titan, the first titanium bicycle frame from a US company. It was a super-light 18 lbs in 1975; now it's a heavy 18 lbs. Of course, Teledyne is one of those aerospace companies. Carbon fiber was just an experiment back then, but carbon-fiber bike frames are now much stiffer and lighter than any titanium frame.They use titanium for bikes? Its not very light (but lighter than steel), usually used for mid to high temp aerospace applications. Nothing like carbon.