The Traxion series of progress capture pulleys, made by Petzl, are an increasingly popular piece of gear. Let's have a closer look the two suitable for alpine climbing, the Micro Traxion and relatively new Nano Traxion.

Before we get into these, a word on the other two flavors of Traxion, the Mini and the Pro.

• The red Mini Traxion is discontinued, but still available used. It’s a fine piece of gear for certain big wall applications, but it's too heavy for most alpine climbing.

• The yellow/black Pro Traxion is popular with big wall climbers to pull up your haul bags, but it's way too big for the alpine world so we're not gonna cover it here. (If you get the Pro, be sure and get the newer model. It’s a big improvement over version 1.0.)

Micro and Nano Traxion: things in common

• Both are rated 91% efficient. (Keep in mind that this “efficiency rating” is tested under optimal laboratory conditions, probably with a low stretch, small diameter rope. My “garage” testing of these devices with an older 8.5mm dynamic rope gives an efficiency of about 72% for the Nano, and about 76% for the Micro.)

• Both have a way to attach a keeper cord. (This is obvious on the Nano, and harder to see on the Micro.)

• Both work on frozen or muddy ropes.

• Both can be used with the 6mm Petzl PURline and RADline static ropes. (This is maybe a little confusing, because the technical documentation for these devices says that 8mm (Micro) and 7mm (Nano) are the smallest diameter ropes allowed.)

• Both are best used with a oval locker or HMS locker, not a D shaped locker.

Micro Traxion overview

• Weight: 85 grams

• Retail price: $130

• Pass a locking carabiner sleeve through the clip point? YES

• Retract and hold the toothed cam? YES

• Rope size: 8 to 11 mm

Nano Traxion overview

• Weight: 53 grams

• Retail price: $100

• Pass a locking carabiner sleeve through the clip point? NO

• Retract and hold the toothed cam? NO

• Rope size: 7 to 11 mm

• Comes in stealth black =^)

Micro Traxion on left, Nano on right. Note the toothed cam is in the “locked open” on the Micro. Can’t lock open the cam on the Nano, but you can open the cam manually and hold it in place.

Both models have a spot to attach a keeper cord, if that’s your thing.

What can you do with a Traxion pulley?

• Set up a drop C system for crevasse rescue, which gives you a 2:1 mechanical advantage, and puts the progress capture on the person in the hole, not on top.

• Set up a “Z drag” system for crevasse rescue, which gives you a 3:1 mechanical advantage and perfect progress capture without futzing with a pulley and annoying friction hitches to hold the load.

• Improvised rope ascending system, combine with a friction hitch or micro ascender like a Petzl Tibloc to go up a fixed rope.

• Top Rope Soloing (TRS). One of the most popular applications for this device. (Nope, you won’t learn that on Alpinesavvy, Google is your amigo.)

• Haul packs or lighter haul bags, with the Traxion on the anchor.

• Set up a “far end haul” with a 2:1 mechanical advantage on the bag. (Nerdy big wallers only)

• You can belay your second directly off the anchor with a Traxion pulley. But it's best to do it on relatively low angle snow or rock, where the chance of a fall is unlikely, and you’re keeping the rope snug on your second so any fall would not create very much force. With a load above about 4 kN you're gonna start to damage the sheath, as shown in the diagram below. If you choose to use the device this way, please be careful. Petzl has done solid testing on this, and has some major cautions . Read more here before you try this technique.

• For putting multiple loads on the same carabiner, it's good practice to put the one receiving the largest load on the spine side of the carabiner. Typically if you're hauling, that's where the pulley should go. See diagram below.

What's the best carabiner to use with a Traxion?

The Petzl website gives a bit of contradictory information about this. On one part of their website, they have a clear diagram that an oval or HMS locker is generally preferred, because it allows the pulley to sit in a more symmetrical position. However, in the technical documentation for the Sm’D carabiner, they have a diagram of that D-shaped carabiner being used with the Micro Traction. See diagrams below.

So . . . my read on that is that is:  while pretty much any kind of locker is acceptable, you're probably gonna get slightly better results with an oval or, what I use, wide gate HMS belay locker.

So, the key question: do you need one?

If you find yourself doing a lot of glacier travel or pack hauling, the answer might be yes. If you're doing more moderate snow climbing and rock climbing without much hauling, then the answer could be no.

This is an expensive item of specialized gear. If you're a beginning climber and building your rack, I suggest getting more commonly used gear first, and perhaps adding this later.

If you already have the Micro, I’d think most people would be pretty happy with this and not want to get the Nano.

If you don't have either, I'd probably recommend the Nano because it's less expensive and lighter and pretty much has the same functionality.

The always amazing Petzl website has a great series of tutorial articles on all the ways you can use this handy device. Read it here.

Finally, check out this short Instagram video that shows using the Mini Traxion for Tyrolean traverse, rope ascending, and large load 1:1 hauling.

(If the embedded video below breaks, you can try here.)