Trek makes their bikes out of one of the three materials, which are: OCLV carbon, Alpha aluminum, and Trek steel. The OCLV carbon is used on the: 9.9 Pro, Elite 9.8, STP 400, STP 300, STP 200, road 5500 and 5200, and the Y Foil fameset.
The Alpha amumium is used on the: mountian: 8500, 8500 LT, 8000, 8000 LT, 8000 WSD, VRX 400, VRX 300, VRX 200, Y3, 7000, 6500, 6500 WSD, 6000, 6000 WSD, 4500, and the 4300, road: 2300, 2300 WSD, Hilo 2000, Hilo 1000, 2200, 2300 WSD, 2000, 2000 WSD, 1200, XO 1, 1000, and the 540, hybrid - comfort - cruisers: 7700, 7600, 7500, 7300, 7200, Navigator 400, Navigator 300, and the Navigator 200.
The Trek steel is used on the: mountian: 820, 800, 800 Sport, road: 520, hybrid - comfort - cruisers: 720, 700, Town & Country, Calypso, and the Cruiser Classic.