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A Guide to Buying a Climbing Rope
By Dave Karl

Dave Karl began climbing in 1978. Over the past 19 years he has worked in the outdoor industry as a retailer, a climbing guide, and as a sales rep. For the past 8 years he has worked with Petzl as their North East Sales Representative.

Which one should you choose?

The Basics: Static Rope (Low Stretch) vs. Dynamic Rope

This one is easy. Static rope is designed to be a fiber version of a steel cable. Climbers likely to need static ropes include cavers, rappelers, and search and rescue teams. These users will find the low elongation and high strength of static ropes perfect for lowering and hauling systems. The durability and minimal bounce of static makes it the only choice for caving. In some climbing gyms static ropes are used for top roping although the C.G.A. (Climbing Gym Association) does not universally accept this practice. Static ropes must never, under any circumstances, be used for lead climbing. This is vital, as they do not have the energy absorbing capacity to safely dissipate the sort of force generated by a leader fall. Even a short leader fall on static rope will impart a tremendous shock load. The danger is not that the static line itself will break, although it could. The real threat is that the falling lead climber is likely to be stopped so abruptly that the forces generated exceed what the body, gear, and belayer can withstand. Static rope users will also require other specialized equipment that is compatible with the system they are building often different from what would be appropriate for dynamic rope customers. I would strongly discourage the use of static for any climbing application. Dynamic ropes will better serve most gyms and certainly all outdoor climbers.

Dynamic rope is of kernmantle construction (i.e., sheath and core) and in this way is similar to static line. However that is where the similarity ends. The dynamic rope's core is composed of bundles of 's' and 'z' twisted, heat treated nylon. The 's' and 'z' twists are essentially bundles twisted in opposite directions; some are twisted clockwise and some counter-clockwise. This alternation is designed to balance the core and eliminate kinking. The core's twist contributes to a certain amount of limited elasticity and energy absorbing capacity. Most of the rope's dynamic properties come from how the core's nylon is heat-treated. The heat-treating process is really where the magic in creating a climbing rope occurs. A good process allows a rope manufacturer to create a rope with dramatically lower impact force and higher fall ratings without a proportionate increase in elasticity.

Ropes for Novice Climbers

The novice in search of a rope for top roping is often interested in a low price above all. Fortunately, this novice doesn't need a fancy, expensive rope to be perfectly satisfied and safe. A basic 10.5mm or 11mm standard non-dry rope will do fine. The 11mm ropes are perhaps a bit more durable, but it really doesn't make much difference. 50m ropes are the norm and will be perfectly adequate for almost all beginners. The majority of top rope sites can easily be set up with a single 50m rope, some webbing or short length of static line, and locking carabiners. A few areas may require a 60m rope to set up a top rope, but for the average top rope climber this is not enough to justify the extra expense.

A bi-color or Half-and-Half rope with a sheath pattern change in the middle of the rope is, for an additional small cost, a great option for any climber. Having a prominent middle mark in a rope allows safer, easier rigging of top ropes. Although unnecessary for most rock climbers, ice climbers and alpine rock climbers will benefit greatly from a dry rope.

Typical Novices Concerns on Rope Performance

A novice's concern over rope wear and tear is commonly focused on sheath abrasion. However, the sheath's abrasion resistant quality has no relationship to the more important issue of the core's ability to survive falls. Do not confuse sheath design claims with a rope's energy absorbing capacity.

Sheath abrasion is a compromise; if you tighten up the sheath you can get additional abrasion and water resistance, as well as make the rope easier for the leader to clip protection. However, the stiffer rope is also a disadvantage for the majority of the climber's other handling concerns. A thicker sheath would also be less likely to wear through, but virtually all of a rope's strength and ability to absorb force during a fall comes from the core. The less core there is, the more likely that the core will experience significant damage, even in a relatively small fall. Additionally, a rope that handles well is not only nicer to use but it is also potentially safer: offering less kinking, reducing rope drag, securing knots, and most often safer belaying.

Information for Experienced Climbers

The previous information should be adequate for the majority of novice climbers interested in buying a rope. However, more experienced climbers may be interested in more technical information. The important UIAA rope characteristics to be aware of are: impact force, fall rating, weight per meter, and to a lesser extent the static elongation and sheath slippage.

Impact Force

The single most important rope characteristic is impact force. The impact force listed on a rope's hang tag is simply the amount of force that the rope can potentially transfer onto the climber's harness and body during the first severe fall. The longer a rope retains its low impact force, the better the rope. The UIAA's maximum allowable impact force on single ropes is 12kN (roughly 2640 lbs. of force). Since a climbing system is not statically loaded but shock loaded, the kN, a unit of force is used on all UIAA certified equipment. Newtons are simply the more accurate and scientific way of measuring force. Force is transmitted to all components in the system; the belayer, anchors, and the leader. The protection that stops the leader's fall is subject to nearly twice the impact that the leader's body sustains. For this reason the UIAA minimum acceptable strength on carabiners is 20kN, almost twice the 12kN impact force allowed on UIAA ropes. The potential for increasingly higher impact forces exist as a rope is used and loses its energy absorbing capacity.

Many of the natural gear placements that climbers make in the field are not ideal and would not be able to handle a 12kN shock load. In fact, many of the leader fall accidents that occur are the result of a piece of protection pulling out of the rock. People usually think that when gear pulls out during a fall the gear must have been placed poorly. It could also result from using an old rope or a rope with impact forces that were too high to begin with. A rope that has a low impact force increases the chance that marginal protection will hold. A quality rope cannot make up for bad protection technique, but even poorly placed protection stands more of chance of stopping a fall if the rope has a low impact force.

Low impact force ropes are able to absorb a lot more of the energy generated in a fall and give a much larger safety margin. As a result of this, there are some that think the UIAA should reevaluate the maximum impact force limit it allows. The new maximum impact proposal is 10kN, which is a substantial reduction from the 12kN currently accepted. If the limit is revised, some of the currently available ropes from some manufactures may not pass minimum UIAA standards.

Fall Ratings

Another specification that you see on all hangtags is the number of UIAA falls that the rope holds before failure. This rating is commonly misunderstood. The current UIAA minimum required fall rating standard is 5 falls. Without going into too much detail, the reason for the confusion is that a UIAA fall is a factor 1.78 static belay fall with the rope going over a simulated 10mm carabiner edge. This is an extremely severe fall and almost never occurs on the cliff. It certainly never occurs ten or more times in a row on the same 8 foot length of rope, but this is exactly what manufacturers subject their ropes to in determining this statistic. When the UIAA test lab tests the rope, they do not stop after the 5 minimum "required" falls. They will continue to do "drops" until the rope fails, and they then report the number of falls that the rope withstood to the manufacturer. Ropes may be cut, but they do not break under normal climbing conditions. Climbers should try not to fixate on this fall rating statistic too much.

Another point which may not be quite as readily obvious, but which can be extrapolated from fall rating information, is the fact that ropes with higher fall ratings maintain their low impact force for a longer period of time. A high fall rating is most useful in giving a climber an idea of how much energy absorbing capacity there is in a rope. The impact force listed on a rope's hangtag is only a measure of the potential force that could be exerted on the leader in the first severe fall. Subsequent falls on the rope result in successively higher impact forces. The longer a rope keeps absorbing energy, the safer and softer the falls will be, and the easier it is for the belayers to do their job. A rope can fail its function without breaking by simply transmitting excessive force to the rest of the system. So, while an initially low impact force rope is super, having a rope that also has a high fall rating means that you're going to retain that low impact safety margin and soft catch on your system for much longer.

For example, even though a 9.7mm rope might have a slightly lower impact force than a 10.5mm, this initial advantage is only on the very first fall, and we use our ropes for longer than 1 fall. Some 10.5mm ropes survive as many as 12 test drops. These cords retain their low impact force for a much longer period of compared with the 8 fall rated 9.7mm rope. When you also consider the potential impact force a severe fall can generate, the performance advantage of a rope with a high fall rating and a low impact force is outstanding! 'Bargain priced ropes' are cheaper for a reason, so I would encourage all climbers to buy the best low impact/high fall rating rope they can find while still achieving their other requirements (weight, diameter, length, etc.)

Weight per Meter and Diameter

Another characteristic to understand is the weight in "grams per meter" of rope. Obviously climbers need to compare ropes of equal weight. Heavier, thicker ropes have more material to absorb energy and the rope's fibers are less damaged overall in a fall. Many climbers falsely assume that a rope with a thin diameter also indicates a rope of lightweight. As a result a few manufactures have taken a lot of liberty in how they measure their diameters. Consequently, some of the impact force and fall ratings that are listed with these understated diameters are misleading. For example, most manufacturers '10.5mm ropes' will weigh between 68- 71 grams per meter. A '10.5mm' rope that weighs 4 or more grams per meter more than another 10.5 is likely not a true 10.5, but in fact comparable in weight to many 11mm ropes. A rope's weight will become apparent on routes that have long and continuously strenuous pitches when most of the rope is hanging from your waist. When trying to compare two different manufacturers ropes look at the weight per meter of each rope, not the manufacturer's stated diameter. However, especially in 11mm ropes, it is important to pay attention to a rope's diameter. An overly "fat" 11mm rope will, after some use, be problematic with certain auxiliary equipment, such as belay devices.

Static Elongation and Sheath Slippage

The UIAA elongation test measures how much stretch a rope exhibits when an 80kg load is statically suspended from it. The old UIAA system permitted single ropes to have as much as 8% elongation, half and twin ropes were allowed 10% elongation. The static elongation figures are listed as percentages, therefore a change of 1% would indicate only a one foot change in stretch over 100 feet of rope. During the initial drop tests the dynamic elongation can be as high as 30%. This test has been revised and now manufactures list the dynamic elongation, usually in addition to the static figure since this gives the user a more realistic comparison of how a rope handles leader falls and behaves in a top rope environment. Like most of a rope's performance statistics, the core determines the static and dynamic elongation properties. It is important to remember that a rope's static elongation has no direct correlation to impact force. The UIAA's allows a certain amount of sheath slippage but anything over 20mm is excessive and undesirable.

Single, Half, and Twin Ropes

As rope technology has progressed and climbing has evolved, thinner ropes have become more popular and lengths have become longer. While the single rope appeals to all, the half and twin ropes are best suited to more experienced climbers.

Single Ropes

Today, the most common everyday climbing rope is the 10.5mm x 50m standard, but 60m lengths are not uncommon. The 60m length in 9.7mm and 10.5mm is especially popular among ice climbers to make sure that they can reach a comfortable belay stance, and among sport climbers who prefer to lower after completing a lead rather than rigging a belay from above. The 60m length also allows a rope with a damaged end to be cut off and still be of usable length. To identify single ropes look at the tape on the ends of the rope and note the '1' in a circle.

As manufacturers improve their rope's core it has become possible to make sub-10mm single ropes. Single ropes of 10mm or thinner are for high-level sport climbing where weight is a primary concern. Manufacturer's sub-10mm ropes may be able to pass the UIAA single rope test, but any of the super thin ropes will hold relatively few falls and they have a very thin 'hand' that can make it difficult for a belayer to stop a severe fall. In sub-10mm single ropes the sheath is often made from thinner yarn, consequently the possibility of an edge causing damage is a big concern. For this reason the UIAA is currently reevaluating the single rope test to possibly include a test drop over an edge. Super thin single ropes may have a hard time passing an edge drop test. The UIAA single rope tests are done with an 80kg (176 lb.) load to simulate the average climber's weight. Climbers that are over the 80kg test weight when fully geared up should consider staying away from ultra-light single ropes. Those under this weight will have a larger safety margin on all of their system's components.

Half Ropes

Half ropes, in the past called 'double ropes', a term now abandoned, are gaining increasing popularity. Half ropes are always used in pairs for technical rock or ice climbing. Half ropes commonly come in diameters of 8mm to 9mm. A half rope system consists of two ropes of equal diameter and different color by the same manufacturer. Half ropes will be marked with a "1/2" in a circle on the end tape of the rope. Half ropes are clipped into protection alternately; one rope into a piece of protection, the other rope clips into the next piece of protection, and so on. Half ropes offer some distinct advantages in certain situations. Used cleverly on a wandering route, they can significantly reduce rope drag, a big advantage in a place like the Gunks where the routes weave between numerous overhangs. Thicker diameter half ropes are a better choice when leader falls are expected; they offer more edge resistance and typically have less elasticity.

Two ropes are far less likely to be cut by falling rock and ice or sharp rock edges and ice gear. Another advantage to half ropes is that if a retreat becomes necessary, you always have two ropes with which to make full-length rappels. Half ropes also tend to have significantly lower impact forces than single ropes. This is a big advantage when a leader is placing his or her own protection (i.e., no bolts). The half rope can also be used as an ultra-light single rope in a glacier travel situation. Half ropes can offer more options, greater security, and a quicker retreat to the more advanced climber.

The UIAA tests for half ropes are done on a single strand with a 55kg load rather than with the 80kg load as in the single rope test. This test can be misleading since the 55kg drop load would obviously be less severe than the 80kg single rope drop load. Typically half ropes should not both be clipped to the same piece of protection, as this has the potential to generate dangerously high impact forces in the event of a leader fall. It is suggested practice for half rope system leaders to arrange protection and ropes so that it is likely that both ropes will eventually be involved in arresting a fall. Although the primary shock in the system is being absorbed by one strand, the second rope engages soon after and diminishes the strain on the other. For this reason the 55kg test drop load is still considered appropriate.

To reduce the dynamic elongation in a fall a long way from the belay, it may be desirable for both strands to be clipped to a single piece of protection. Some of the better lighter half ropes carry a dual certification is both half and twin ropes allowing them to be clipped as a single rope, the best possible scenario. If different amounts of rope are out and the ropes are being clipped to the same piece of gear it is sometimes suggested that a separate quick draw be used for each rope. This will prevent the ropes from rubbing against each other in the same carabiner due to their different elongations.

Twin Ropes

Twin ropes are not commonly used in the United States. They are designed for extreme routes in the big mountains. Twins usually come in diameters less than 8mm. Twin ropes will be marked with an infinity symbol on the end tape of the rope. A twin rope system must have two identical ropes (preferably in different colors) from the same manufacturer. Using any half or twin rope system also requires better rope management to keep them from getting tangled.

As their name implies twins are also used in pairs, but unlike half ropes the pair must always be clipped together into all pieces of protection. UIAA twin rope drop tests are done with an 80kg load, as on a single rope, but unlike half ropes both twins arrest the fall. Twin ropes simply are not strong enough to pass the half rope tests. Twins offer the same cut resistance and rappelling advantage of a half ropes, but lack most of the main advantages that a half rope system offer, reducing rope drag and increased protection options. Perhaps most importantly twins also tend to have relatively high impact forces, often significantly higher than a single rope and certainly higher than any half rope. To address this concern users may wish to have an extra foot or two of rope out on one strand when belaying a leader. This helps reduce to peak impact forces that a twin rope system can generate. Most twins are also a bit too light to ever use singularly on snow, as they tend to slice through the edge of a crevasse too easily. They are also so thin that a secure belay on one strand is nearly impossible. Likewise many of the belay devices manufactured are also incompatible with sub 8mm ropes. Obviously a twin rope system significantly limits the versatility and security that is offered by marginally heavier half rope systems.

Other Rope Options to Consider

A bi-color or Half-and-Half, in addition to being a valuable feature for entry-level climbers, also has many benefits for the experienced lead climber. The belayer can easily see if he or she has enough rope to lower the leader back to the belay stance. The smart leader can also easily alternate the wear and extend the life of a rope during repeated leader falls by switching lead ends between attempts. Of course these ropes also allows easier, potentially safer rappels. These ropes are especially popular in 60m lengths.

Unless a climber plans to ice climb, a dry rope is not necessary. All ropes showing signs of wear (fuzz) have more surface tension than new smooth ropes and water molecules will penetrate worn ropes easier. Therefore, all dry treated ropes lose some of their water resistance with wear. Dry treatments provide minimal additional abrasion resistance, and no manufacturers abrasion cycle testing has shown otherwise.

Safety

I encourage climbers to take care of their new rope and to buy a rope bag or tarp. Making use of a history card for recording a rope's usage is important. After one severe, long, hard fall a rope should be retired from climbing use. A rope showing flat or soft spots, becoming stiff or showing signs of sheath wear should be retired, or at the very least be used only for top roping. Ropes should be retired if there is any doubt. Retire ropes after no more than 4 years of occasional use, two years of recreational use, or one year of active use. Retiring a rope after only a few months of extensive climbing is not unusual. As stated earlier, a rope that visually appears to be fine can easily have lost much of the energy absorbing capacity that it needs to keep the rest of the system safe. In addition to choosing a good rope and replacing it when needed stack the odds in your favor by carrying and using shock-absorbing quickdraws on marginal gear especially ice screws.

Any rope systems single, half or twin, could potentially be cut over an edge if the edge were severe enough. Contamination by chemicals or acids has typically been the underlying cause of rope failure. The half or twin rope system has never, that I know of, had a failure where both ropes broke or were both completely cut over an edge.

Testing and Manufacturing

One final point to be aware of is that many climbers assume that each and every rope has been individually tested. This is not the case. Ropes are batch tested and the rope that you or any other climber uses has never been individually tested. This is because ropes are destroyed in the testing process. The only assurances that you can get regarding the quality of your rope are a manufacturer's reputation for consistency and quality control.