I was speaking to someone who belays a heavy climber. When the heavier climber falls, the belayer gest pulled into the air. I asked how they don’t get stuck in the air and the belayer said to get back to the ground, they start putting slack through as if they were lowering the climber, but it lowers them to the ground, and then when they’re on the ground, they carry on feeding the rope through in the same way and it lowers the climber.
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Why does the slack lower the belayer first, and what makes it change to lowering the climber once the belayer is back on the ground? All I can find from searching is that friction makes it possible to belay someone heavier, which makes sense, but why does letting slack out work differently when the belayer is off the floor?
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Is it because the belayer is close to where the most friction is (so the belay device), and when they’re no longer putting weight on it (so they’re stood back on the ground) , the slack makes it past the belay device and up to the climber?
Edit: Thank you so much for the replies everyone! If I’m understanding correctly, there’s not so much friction on the belayer’s side, so letting out rope makes them descend first due to the lack of friction, and there’s more friction on the climber’s side because the rope goes through the belay device and carabiners.
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The reason is that there is friction where the rope does a 180 degree turn at the top. If you replaced the carabiner with a frictionless pulley then whoever was heavier would descend first.
Because the protection between the belayer and climber is adding friction. The belayer hanging on the device feels no addition friction between them and the brake, so when they try to lower, they will usually lower first. It’s not until they hit the ground and can partially unweight their end that the climber’s weight will pull out slack.
the answer is the friction in the belay system. if the climber and belayer are about the same weight, there is friction in the rope bends will hold the climber in place until the belayer is back on deck.
when lead climbing there are multiple carabiners adding friction. when top roping, there are at least one pair of carabiners adding friction to the system. so the belayer is on the side with less friction, since it’s just the belay device. the climber has the rope bend plus all the other carabiners which have friction. they’re not pulleys with zero friction this is the real world we live in. you cannot assume no friction in the equation.
Just to build on what others have said, there’s no friction between the belay device and the belayer, and a ton between the belay device and the climber, simple as that.
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