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Pulley efficiency: comparison with Petzl

Tuomas Pöysti 2020

I’m not fortunate enough to own a Petzl Maestro, or know anyone who would lend me one for efficiency testing. When I got the opportunity to test MPD and Clutch, I was fully aware that Clutch and Maestro would have been way more interesting pair.

About the same time Petzl published an informal test series about some pulley efficiencies. They gave pulling “forces” needed to haul a 100kg load using different devices, an 11 mm rope and apparently a 180° deviation:

  • Maestro 122kg
  • Pro Traxion 113kg
  • Microtraxion 120kg
  • Rollclip 130kg
  • I’D 326kg

To change these into efficiency values, we need to divide 100kg by each:

  • Maestro 81.9%
  • Pro Traxion 88.5%
  • Microtraxion 83.3%
  • Rollclip 76.9%
  • I’D 30.7%

Luckily I have my own versions of all except Maestro. Read here (I will publish another article about descenders soon). As a comparison between Petzl’s values and mine:

  • Pro Traxion 88.5% – 89%
  • Microtraxion 83.3% – 82.5%
  • Rollclip 76.9% – 76%
  • I’D 30.7% – 24.5%

I would not be concerned about I’D. They probably used a newer version, and in any case the rest of the devices are practically identical.

That’s why I’m positive that when I one day get my hands on a Maestro S and measure it’s efficiency, I’ll end up very close to 82%.

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