The Bachmann knot (sometimes misspelled ‘Bachman’) is a friction hitch that was invented by Franz Bachmann. The Bachmann knot makes use of a carabiner as a handle to ease shifting the knot up and down the rope. It does not matter if the carabiner is locking or not. Most importantly, the carabiner must be of round cross section for friction. Grabbing hold of the carabiner will release the friction and allow the hitch to slide freely and thus be moved up or down appropriately. Like the Klemheist knot, the Bachmann only works when pulled in one direction.
Bachmann hitch is a popular with climbers and arborists. It is useful when the friction hitch needs to be reset quickly/often or made to be self-tending as in self-rescue. Using the carabiner will allow the Bachmann to move much easier than it\’s relatives, especially when wearing gloves. A Bachmann knot is a better friction knot than a Prusik knot to ascend a rope since it is easier to untie after it is weighted.
It is safer to use a locking carabiner rather than a regular one so that there is no chance that the cord can come out of the carabiner. With non-locking carabiner it is safer to use the knot with carabiner gate opening facing down. This decreases the risk of self-unclipping: at maximum, one twist goes off. Otherwise, the whole knot may fail.
Bachmann knot, Bachman knot