1. What is the titanium bike frame advantage ?
(1) Titanium is extremely resistant  to corrosion.This property has lead to titanium's usage as storage containers for caustic materials in the chemical industry.For you as a cyclist,this means that all the saltly roads,messy mud and stream crossing you ride over or through will not rust your bike ever.Titanium frames are lifetime frames
(2) The density of titanium is nearly twice that of aluminum,but only 56% that of steel.This means titanium can be as stiff as steel,but lighter than steel.Titanium has a high perfect stiffness-to-weight ratio
(3)Titanium's 20-30% elongation(elongation numbers of a metal tell us how much a material will bend before it breaks) beats out steel's 10-15% and aluminum's 6-12%.The lower the elongation number,the more brittle and breakable a material is.So,the same amount of titanium stretched out into a tube will less than amount of steel or aluminum.Carbon fiber does not stretch,itmust be molded into form.
(4)Fatigue strength is another measurement taken into compare metals.Fatigue is the result of accumulated wear from repetitive cycles of force.Aluminum is notorious for having such a low fatigue strength that there is no threshold,no level of strain below which the metal will not fail.This means that the strian on a bike frame from each pedal stroke contributes to the frame's fatigue failure