Although you read about elongation in the Mammut 8.5 MM Genesis double rope, I never really grasped the full meaning until I watched one of my climbing buddies pop off a climb from about 10 feet off the ground. (She was seconding Double Crack at the gunks, a 160 foot climb). A 9% elongation factor= ~14 1/2 feet with 160 feet of rope out.

Anyway, my friend came off and watching the rope and my friend, it looked as if the belayer (who had set up the belay using an autoblock) let her zing through the belay device. My friend hit the ground at what looked like full force, as if she was not roped up at all. She landed on her tail bone and although it's not broken, it's mighty sore and really limiting her ability to get around.

So, just another thing to think about when you are bringing up your second.