The 2025 Trek Top Fuel 9.9 X0 AXS Gen 4 is a full-carbon trail bike engineered for riders who want lightweight agility and modern adjustability without sacrificing capability. Built from Trek’s OCLV Mountain Carbon, it features 120mm of rear travel paired with a 130mm RockShox Pike Ultimate fork up front, plus a 4-way Mino Link to tweak geometry and suspension leverage for different terrain. The wireless SRAM X0 T-Type drivetrain (1×12) delivers fast, clean shifting, and the SRAM Level Silver 4-piston hydraulic brakes provide strong stopping power. Tubeless-ready carbon wheels, internal storage, and generous 2.5-inch tire clearance round out a spec that balances cross-country speed with trail versatility.