Descending / rappelling
The preferred choices for descending ropes while caving are the 6-bar J-frame rack (aka Cole rack), the 4-bar micro-rack, and the bobbin. These devices have the common benefits of allowing a lot of friction control in a variety of conditions, a friction path that won’t cause a twist in the rope, the ability to attach and detach the device from a rope without disconnecting from the harness, and a long track-record of safety.
Bobbin descenders utilize a pair of bobbins (aka spindles or pulleys) that are fixed and generate friction as the rope passes around them. They are one of the shortest and lightest descenders, and are easy to carry through a cave. The short length and ease of inserting and removing the rope make them ideal when negotiating alpine rigging that relies heavily on rebelays and deviations.
The Petzl Stop is widely used in vertically intensive international caving areas such as Mexico, Europe and China. In 2019 the Stop has been redesigned and now is fully stainless steel, and has a new spring-loaded release lever.
The Petzl Simple is the modern version of the original bobbin from the 1960’s. It has seen only minor changes over the past 50 years. In 2019 Petzl is releasing a new version of the Simple. The only significant change is a larger oval slot in the fixed side plate that accommodates the new version of the Petzl Freino carabiner.
Micro-rack descenders utilize a U-frame and usually four brake bars. They also have 1-2 hyper-bars. They are a good alternative to bobbins for use with a Frog ascending system for those who prefer the versatility and function of a brake-bar rack.
Open J-frame racks are preferred in the southeastern US and on very long free rappels over 100 meters (300 feet). The standard version of this device, originally designed by John Cole in the 1960s, is a frame that is 14 inches in length with 6 brake bars.