all i keep seeing new tubes etcon ads what is that? and is it important, are these expensive?There are TWO Different kinds of tubes on a bicycleThere is the rubber Inner Tube which holds air in the tireCosts about five dollarsAnd There are metal Tubes (very similar to metal pipe) that the bike is made ofThe metal tubes are different from the plumbing pipes which carry water in your houseFrame Tubes cost more money if they are special alloysThe goal is to make the bike out-of the strongest and lightest material Mild Steel is very cheap, but the bicycle will weigh about 50 poundsChrome-Molybdinum steel is stronger than mild steel , so the tubes can be made thinner to save weightCr-Mo bikes will usually weigh about 35 poundsAluminum is lighter than steelan aluminum bike will usually weigh about 27 poundsTitanium is stronger and lighter than aluminum, but is very expensiveExpect the price to be over six thousand dollars, and the bike will weigh under 22 poundsCarbon fiber is a composite material, it must be glued and not weldedCarbon Fiber costs about seventy dollars an ounceA carbon fiber bike will weigh about 18 pounds and cost as much or more than $20,000.00.Other related question