Frog Ascending system - footloops
The Frog SRT system utilizes an upper ascender that is usually a handled or non-handled ascender that is connected to the seat harness with a cowstail / lanyard. There is also a footloop attached to this ascender that is generally a length of cord, rope or webbing that is used to stand in during the stand portion of the Frog sit-stand cycle. Many cavers make their own footloop from cord or webbing, but there are several commercial options from Petzl, GGG and Elevated Climbing. Footloops can be configured for use with one foot, two feet, or the option of one or two feet. The one-foot configuration is often used when the vertical pitches are short and/or low-angle. If a single footloop is used in caves with longer free-hanging rope pitches then it is often paired with a foot ascender such as the Petzl Pantin on the opposite foot.
The footloop is not a life-safety rated part of the climbing system, but it should be strong and durable because it can see relatively high forces and is subjected to a lot of abuse. Footloops may also be used in certain types of rescue maneuvers such as pick-offs, and so they should be much stronger than body weight. It is also an advantage to make footloops out of very static material because they are used to make upward progress when ascending the rope and any dynamic stretch in the footloop reduces climbing efficiency. The best material for footloops is UHMWPE (e.g. Dyneema or Spectra) due to it’s extremely low stretch, high strength to weight and size, and extremely good abrasion resistance. The only drawbacks to Dyneema are the higher cost and lack of availability. Nylon footloops are more common, and easier to make yourself, but sacrifice a little in climbing efficiency and durability. Many cavers who make their own footloop will measure, tie and cut to the desired length. If properly adjusted then there is almost never a need to change the length; however, most commercially available footloops come with a cord-lock or buckle to adjust the length to fit a range of cavers of different height. Adjustability can be an advantage if you’re still tweaking your Frog system and aren’t quite sure what length is most efficient, if you might loan your vertical gear to another caver, or if it will be part of a club’s vertical kit.
