Black Diamond’s NForce ascender utilizes a unique four-bar linkage system that allows the handle to track up and down. This action pivots the cam and generates more clamping force when you weight the ascender. The result is a tool that grips icy and muddy ropes better than conventional jugs.
In the field, the NForce performs with the ergonomics climbers have come to expect from Black Diamond. The grip is comfortable and the ascender is easy to pluck off the rope when you’re passing knots or frigging at anchors. The cam-stop works to keep the ascender seated during horizontal maneuvers, but is tooled to allow unimpeded manipulation with the trigger finger. The device is difficult to remove using your thumb. No big deal. These ascenders fit large hands and accommodate gloves.
My concern, when confronted with the extra-mobility afforded by the four-bar linkage, was that the NForce would gum up and become sticky. I used the jugs for a season of gritty sandstone ascents, however, and so far the action is as smooth as on the first day.
In situations where you’ll be big walling or ascending fixed lines in icy or muddy conditions, these ascenders could add a degree of utility.