Trek Speed Concept Stack and Reach

The Trek Speed Concept is a dedicated triathlon and time trial (TT) machine where stack and reach are analyzed with millimetric precision. Unlike road bikes, TT bike geometry is focused on the relationship between the Bottom Bracket and the arm pads. The frame stack and reach of the Speed Concept are designed to be extremely low and long to facilitate an aerodynamic “tuck.” However, Trek uses a unique “Tower” system for the cockpit, allowing for significant adjustment of the arm pads independently of the frame.

In a TT context, the frame reach is often shorter than a road bike because the rider is leaning forward onto the aero bars. The Speed Concept’s geometry is optimized for straight-line speed and aerodynamic integration. When fitting a Speed Concept, the goal is to find a frame size that allows you to reach your target Pad Stack and Pad Reach (the coordinates of your elbows) within the mid-range of the adjustment towers. This ensures maximum structural rigidity and leaves room for future adjustments as your flexibility or aerodynamic needs evolve during the racing season.