Different types of climbing require different types of ropes. Lead climbing (sport or trad) requires a dynamic single rope that will stretch to absorb the impact of a fall. Static ropes do not stretch and are preferred for rappelling, ascending fixed lines, and utility work. Half-rope systems are used on wandering traditional and alpine routes to cut down on weight, reduce drag, and provide a second rope for descent. Twin-rope systems add security on traditional routes where rough terrain could potentially cut a rope. Additional features like dry coatings, middle marks, and bi-patterns are beneficial but are not necessarily required for a rope to safely perform.
Whenever you’re climbing on lead, you need a dynamic single rope that will stretch to help absorb the impact of a fall. Typically, a rope diameter between 10mm and 11mm will offer more durability and is ideal for regular use. A skinny rope between 9mm and 1 mm is best employed on difficult ascents where every ounce counts. A 60 meter length is considered the standard for most single pitch sport and trad routes.
Static ropes are highly durable and do not stretch. They are typically used for rappelling, ascending fixed lines, and utility applications like pulling up a haul bag on a multi-pitch route.
Although similar in appearance , half and twin rope systems are each designed for specific applications. Half ropes are independently rated and can be clipped into alternating pieces of protection. Half ropes help reduce weight and drag on wandering trad and alpine routes. Twin rope systems require both ropes to be clipped into every piece of pro and provide extra security where sharp terrain could damage or cut a rope.