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Krok Chest Strap Ascender

Front View: Closed Rear View: Closed
Front View: Closed Rear View: Closed
Front View: Open for Rigging Rear View: Open for Rigging
Front View: Open for Rigging Rear View: Open for Rigging

Technical Details

I acquired my Krok Chest Ascender from Gear4Rocks in 2012.

The Krok Chest Ascender is 114 mm. tall, 69 mm. wide, and 31 mm. thick, and weighs 147 g. The ascender is left-handed, as are virtually all chest ascenders that I have seen. The ascender shell is subtriangular shape bent from 3.8 mm. aluminum sheet. The rope channel is formed by bending the right side of the ascender into a squared-off U. The rope channel is 15.2 mm. wide. The main sling attachment point is a 19.2 mm. hole located below the cam and behind the rope channel. The lower left side of the hole is bent backward to allow a carabiner to rotate parallel to one's chest. A second attachment point lies above the cam, also behind the rope channel. The left end of the shell is bent on an inclined axis to form another U. A hole drilled through both sides of the U accepts a steel rivet. The cam and cam spring are mounted on this rivet. The pivot is centered 32 mm. from the inside of the rope groove. There is a cylindrical cam stop above the cam.

The cam is a skeletonized steel casting. The cam radius, measured from the pivot, increases from 37 to 58 mm. over an angle of 41°, giving a 32° cam angle. The tooth pattern is (3.2)(2.2.H)^3( A spring-loaded manual safety bar pivots on an axle riveted to the cam. The normal action of the spring holds the safety against the cam. When the cam is opened, the shell interferes with the safety bar, thus preventing opening the cam. If the safety bar is moved away from the cam (opposing the spring), it will clear the shell and the cam will open. At full open the safety can be released and the spring will hold the safety against the back of the shell. This provides a means of locking the cam open. Two pins on the safety assist in operating the safety mechanism.

The front of the rope channel is stamped with the Krok logo, a book-with-an-"i" icon, and "06 11."


The cam safety is both awkward an unique. Opening the ascender one-handed is rather difficult. When the cam hold-open is active, releasing the cam is easy; a light tap will cause the spring to pull the cam closed.

The workmanship and finish on the Krok are adequate but inferior to many Western ascenders. Gear4Rocks advertises their equipment as "functional, serviceable, affordable & safe, not pretty or trendy." The ascender design has been tested by "STANDART," the Ukrainian National Scientific-Certification Center in Kiev, the capital of Ukraine. Testing procedures are based on CE and UIAA standards.