How to Pick a Climbing Rope
This followed on from the shoes and harness posts and it is still the right third step. The specifications have moved a little; the logic has not.
Diameter first, and thicker is right for a first rope. Something in the 9.5 to 10.2mm range is durable, handles well, and works with every belay device. Skinny ropes under 9.2mm are for experienced climbers saving weight on long routes and they wear out faster and run through a device much more quickly than a beginner wants.
Length: 60m is the standard, 70m is the safer buy. This has shifted since this was written. More and more sport routes are pitched for 70m, and being 5m short at the top of a route is a genuinely bad situation. If you only ever climb indoors, 40m is plenty.
Single, half or twin matters less than it sounds: buy a single rope. The others are for specific alpine and ice applications and the marking on the rope end tells you which it is.
Dry treatment is worth it if you climb anywhere wet or on ice, and a waste of money on indoor and dry-rock climbing. A wet untreated rope is heavy and significantly weaker.
The things that actually keep a rope safe: a rope bag so it never sits in grit, which is what cuts the core from inside; running it through your hands after any hard fall to feel for flat spots; and knowing the manufacturer's retirement guidance, which is a matter of use rather than only age. Retire it immediately after a serious fall over an edge, a sheath cut, or any chemical contact.
Buy new. The one piece of kit where second-hand is never worth the saving.
Part of the guide to climbing and mountaineering.