page_title: Rope drag
hierarchical_section_title: Rope drag
caption_attribution_description: Rock climbing in Lion's Head, Ontario @ May 24-25, 2008
context_page_description: In rock climbing, rope drag is the friction of the rope plus its weight that the climber feels when pulling a rope through a number of protection points, or over rock prominences. A large number of anchor placements, especially if they form a zig-zag rather than a straight line, can make the rope drag so bad that the climber can hardly move forward.
  Let’s assume a situation where the rope runs through several carabiners which are not all aligned. By using the equations of Euler-Eytelwein to describe the dry friction between the rope and the protection points, the rope drag can be calculated. It can be expressed by an effective mass of the rope that the climber has to pull, which is always larger than the rope mass itself. This effective mass depends exponentially on the sum of the angles of the direction changes the climber has made. “Early errors” by not using longer runners to reduce the angles at the first protection points are less severe than “later errors”, which is plausible when considering that the higher friction points are pre-loaded with more weight from the rope itself.
context_section_description: In rock climbing, rope drag is the friction of the rope plus its weight that the climber feels when pulling a rope through a number of protection points, or over rock prominences. A large number of anchor placements, especially if they form a zig-zag rather than a straight line, can make the rope drag so bad that the climber can hardly move forward. 
  Let’s assume a situation where the rope runs through several carabiners which are not all aligned. By using the equations of Euler-Eytelwein to describe the dry friction between the rope and the protection points, the rope drag can be calculated. It can be expressed by an effective mass of the rope that the climber has to pull, which is always larger than the rope mass itself. This effective mass depends exponentially on the sum of the angles of the direction changes the climber has made. “Early errors” by not using longer runners to reduce the angles at the first protection points are less severe than “later errors”, which is plausible when considering that the higher friction points are pre-loaded with more weight from the rope itself.
  The chances of rope drag occurring can be reduced by using two ropes in parallel instead of just one (so that for each point of protection, the nearer rope can be used), using carabiners with integral pulleys (such as the DMM Revolver), or by using slings to extend protection so that the rope can stay in a straight line. If drag still happens, then the climber may need (if possible) to stop and set up a belay point sooner than expected.
  Rope drag on a dynamic climbing rope also effectively reduces the length of rope available for absorbing fall energy (or, in other words, effectively increases the rope's modulus of elasticity), resulting in higher fall impacts than would be expected using a simple fall factor calculation.
caption: Use of quickdraws attached to anchor points to keep the climbing rope straighter
exif: {"Image Make": "Canon", "Image Model": "Canon EOS 20D", "Image XResolution": "150", "Image YResolution": "150", "Image ResolutionUnit": "Pixels/Inch", "Image DateTime": "2008:06:10 08:09:29", "Image Artist": "Alex Indigo", "Image Copyright": "Creative Commons Attribution 3.0 License", "Image ExifOffset": "244", "GPS GPSVersionID": "[2, 2, 0, 0]", "GPS GPSLatitudeRef": "N", "GPS GPSLatitude": "[45, 0, 12114/625]", "GPS GPSLongitudeRef": "W", "GPS GPSLongitude": "[81, 13, 22925/653]", "GPS GPSAltitudeRef": "0", "GPS GPSAltitude": "8949/50", "GPS GPSMapDatum": "WGS-84", "Image GPSInfo": "614", "EXIF ExposureTime": "1/1250", "EXIF FNumber": "28/5", "EXIF ExposureProgram": "Aperture Priority", "EXIF ISOSpeedRatings": "400", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2008:05:25 01:46:45", "EXIF DateTimeDigitized": "2008:05:25 01:46:45", "EXIF ShutterSpeedValue": "321491/31250", "EXIF ApertureValue": "2485427/500000", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "159/32", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "100", "EXIF FocalPlaneXResolution": "31750/11", "EXIF FocalPlaneYResolution": "2704000/937", "EXIF FocalPlaneResolutionUnit": "2", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF SceneCaptureType": "Standard"}