Reddit reviews PETZL - Mambo 10.1, Single Rope for Gym or Crag Climbing, Blue, 60 m
We found 1 Reddit comments about PETZL - Mambo 10.1, Single Rope for Gym or Crag Climbing, Blue, 60 m. Here are the top ones, ranked by their Reddit score.
MULTIUSE: The MAMBO's diameter is appropriate for gym or crag use.UNBELIEVABLY DURABLE: The core and the sheath are bonded together at the rope ends by an ultrasonic process called UltraSonic Finish; gives greater durability and avoids frayed ends.READY TO USE: Features ClimbReady coil that makes the rope ready for use and helps the user avoid initial uncoiling mistakes and increases longevity.MORE EFFECTIVE BRAKING: Middle Mark indicates the middle of the rope to facilitate maneuvers.INCREASED STABILITY: EverFlex is special thermal treatment that stabilizes the core strands and improves consistency; offers excellent grip and consistent handling over time.
Let's plug in some numbers to find out! Let's say my gear and I weigh
650 newtons (146 pounds)(edit: no, see below), I take a fall from 1 meter above this placement, and the angle between the nuts is 150 degrees (note that the image in question has 1 nut significantly higher than the other; to make the math easier, I'm going to assume they're at the same height). I will fall 2 meters before the rope catches me, and that'll take a total of 0.64 seconds, resulting in a final speed of 6.3 meters per second. I'll thus have a momentum of 6.3 m/s 650 kg = 4095 kg m/s. The rope is a little stretchy, so let's suppose it takes half a second from when the rope goes taught to when I'm stopped (is this a good estimate? I have no idea. Longer times will lead to smaller forces edit: it's a bad estimate; see the re-re-edit below). The upward force exerted on me during that half second is now 4095 kg m/s / (0.5 s) or 8190 N, and thus the force on each nut is 8190 N / (2 cos(0.5 150 degrees)) or about 15.8 kN.Yes, they're going to rip right out.edit: oh, crap. My estimate at the very beginning was wrong because I mixed up mass-pounds with force-pounds before converting to metric. Suppose instead my gear and I weigh 65 kilograms (143 mass-pounds). Now, my momentum is a mere 409.5 kg m / s, the force needed to stop me is only 819ish N, and the force on each nut is just 1.58 kN. The nuts will hold just fine. Serves me right for not having enough familiarity with metric units.
re-edit: even if I start 2 meters above the nuts and fall a total of 4 meters, even if catching the fall takes a quarter second, that only exerts 4.5 kN on each nut. I'll be alright. Thanks for pushing me to run some actual numbers through this!
re-re-edit: my estimate of how long it takes to stop a fall is way off. I should just look at the impact force (the force exerted on the rope when an 80 kg weight takes a 4.8 meter factor-1.7 fall). As an example, the Petzl Mambo rope has an 8.5 kN impact force, which means the force exerted on each nut in that fall (with my weight instead of a standard weight) would be 8.5 kN / (2 cos(0.5 150 degrees)) (65 kg / 80 kg) or 13.3 kN. I'm back to thinking this isn't so safe.