Back in November 2009, Jim "The Tree Machine" Clark wrote about a concept single-handled dual ascending device in the TCI Magazine.
In the TCI article The Tree Machine says the basic requirements for the ideal arborist ascender should be as follows:1) The ability to accommodate easily all three rope techniques - 2:1 doubled rope technique (DdRT), 1:1 single rope technique (SRT) and 1:1 twin line ascent (DdRT).
2) Compactness of design and intuitive, one-handed ease of use.
3) Elimination of the need to 'slack tend".
4) The ascender should carry with it redundant safety features to eliminate the need for external backup.
5) Instant and one-handed downward adjustability.
Now CMI have released the Twin Expedition ascender, designed specifically for arborists, which according to the CMI promotional material reaches all of Jim's criteria.
The cam (note the lack of 'teeth') on the Twin Expedition features a new coating process and CMI claim it is so good the cam will NEVER wear out… ever! The cam is not available as a spare part (to purchase) so if yours does wear out… CMI will replace the cam for free.
If we can lay our hands on a sample CMI Twin Expedition ascender, Treetools will get one in for appraisal - then we will be in a better position to judge how good it really is.
Thanks to Rossy Ross from Pro Climb for this lead.