Trek Procaliber

Procaliber is Trek's carbon XC hardtail, introduced in 2016 as the bike that took the popular Superfly hardtail platform upmarket. Its defining feature for nearly a decade was IsoSpeed — a decoupled seat-tube/seat-stay junction with a small elastomer-damped pivot, borrowed from Trek's Domane endurance road bike, that allowed the seat-tube to flex fore-aft for vibration damping without adding weight or affecting pedalling. For the 2025 model year (Gen 3) Trek replaced IsoSpeed with IsoBow — a tuned tubing junction that delivers roughly 80% of the compliance with no bearings, no hardware, and a 150g frame weight reduction. The Gen 3 frame weighs a claimed 1,150g (medium), runs a 67° head angle and 120mm fork, and is the lightest carbon hardtail Trek has ever made. It sits below the full-suspension Supercaliber in the XC race hierarchy but is the choice for marathon racers, weight weenies, and singlespeed/rigid converts.