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How to Trim / Cut Ski Climbing Skins

 
 
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evo Size & Buying Guides - We have one of the largest selections of climbing skins on the web, a super knowledgable staff and expert guides to help you make an informed decision.

 
Trimming climbing skins can take a little patience and attention to detail, so don’t save it for the last minute. There's nothing worse than cutting your skins in the parking lot the morning before you go touring. Your friends will not be impressed. Give yourself some time and read the directions that come with them because each skin and cutter has its own quirky charm. Plus, you just paid a bunch of money for your skins so get it right!
 

Precut Skins

For starters, not all climbing skins need to be trimmed. If you purchased Dynafit skis, for example, and bought the matching length and model of Dynafit climbing skins, then the skins will fit your skis perfectly out of the box. All you need to do is put them on and go. Some K2 climbing skins are also pre-cut to fit a specific model and length of ski and require no trimming. Also, if you go with straight skins, which are a uniform width from tip to tail (preferred by most randonnée racers because of superior glide), all you need to do is buy the right size for your ski’s waist width, and cut the skins to the correct length. 

If you don’t fall into one of the above categories and your skins’ shape doesn’t yet match your skis’ footprint, you’ll need to trim them. While you should always follow the instructions that come with you climbing skins because they vary from each manufacturer, here are some tips to help you trim your skins.
 

Trim-to-Fit Skins

Length

Some skins require adjusting the length of the skin before trimming the sides. For these skins follow the steps below:
  • Set up your tail strap with the hook in one of the middle notches (Black Diamond suggests the 4th or 5th hole for its STS series skins). Don’t worry about covering the ski all the way to the end – the tail of the skin doesn’t add much grip. 
  • Apply the skin to the ski while pulling firmly to stretch the skin material – you may want to repeat the stretching process to make sure the skin is fully stretched out. 
  • Adjust the tip loop so that it fits securely over the tip of your ski (a wide opening that slides further down the tip is usually more secure and less likely to pop off while skinning). 
  • Mark the spot where the tip loop ends with a Sharpie and cut the skin here. 
  • This is also a good time to taper the tip of the skin to form a smooth curve – mark the width of the tip loop and draw a curved line out to the contact points of the ski. A pair of strong scissors or poultry shears works better for this than the cutter that comes with the skins.
Note: Some older models of Black Diamond and G3 skins (with the non-adjustable tip loops) require cutting a long, tapered section at the tip to hold the tip loop. If you have this type of skin, you’ll need to cut the length longer than the mark (usually by 4-5 inches) and trim it to fit the width of the loop.

Black Diamond precut-to-length models (called “Custom” in the product description), newer G3 skins, and trim-to-fit K2 skins come sized for a specific ski length but require the user to trim the sides. If you’re ordering this type of skin, just pick the correct length or the range of lengths that fits your skis and make sure the width is adequate to cover your bases. We recommend a skin that is roughly 5-6 millimeters narrower than the widest part of your skis (the tip) for full coverage, but slightly narrower is usually fine too.

If you bought skins that are pre-cut to the right length, skip the part about cutting the skins to length and installing the tip loops (Z-clips in the case of K2 or pivoting hooks in the case of G3) as they will already be attached. You’re ready to trim the sides of the skins to match your skis.

Width

When trimming skins, the idea is to cover all of the polyethylene base material with the skin but leave the metal edges showing.

 
It’s not too important to cover the entire base at the very tip of the ski, since that area contributes very little traction, but from just ahead of the toepiece to a foot in back of your heel you definitely want “wall-to-wall” coverage. Skins that are too narrow under your feet (with strips of base showing) will slip backward more easily on off-camber tracks or hard packed snow; skins that are too wide (the ski edges are covered) will not hold an edge well on sidehills or icy traverses.
 

Trimming and Cutters

Different tools are available for cutting the sides of skins. The old-school standby was the straight edge razor blade (SERB). If you started shaving a long time ago or lived through the eighties you may remember these. SERBs are excellent for starting a cut on an angle and don’t clog up easily, plus they are available at any hardware store.

Cutters, bottom to top: Straight edge razor blade, Black Diamond, G3, K2.
Seated: Benevolent Buddha of Plentiful Powder

 
Black Diamond includes something that looks like a letter opener (it is) with their skins, which works well and cuts cleanly, but requires moving the skin back and forth to account for edge width. You can do a good job of trimming skins with the BD tool even if you only have a wall or table to lean the skis on.

K2 and G3 both include cutters that use the ski edge as a guide but offset the cutting blade by a few millimeters. When you use these cutters, you only have to lay the skin down once before cutting both side edges. Both of these offset cutters work better if you have a ski vise that will hold the ski securely on its side.
 

Hints for using the three proprietary cutters:

Black Diamond Tips 

  • Do as BD recommends and lay the skin down roughly 2 millimeters off center. This is an estimate - touring ski edges vary in width from about 1.6 mm to 2.5 mm. 
  • Make your first cut on the side with more overhanging skin, moving from tip to tail. 
  • Remove the skin from the ski and move it over away from the side you just cut so that an edge width worth of ski base shows (to accommodate for the other edge). 
  • Carefully position the skin with ~2 mm of the ski base showing all the way from tip to tail, then cut the other side. 
  • Presto, you’re done. 
  • With the Black Diamond cutter, it helps to bend the plastic letter opener slightly over the ski base and press down on the skin as you cut; this helps hold the skin in place and assures that the cut won’t be wavy. The BD cutter is good at initiating cuts at a sharp angle and works well on a flat table or with the ski leaning against your kitchen counter. 
  • Note on STS Split Skins: Black Diamond recommends starting with the skin perfectly centered with its Ascension Nylon Split STS skins (the ones with the white nylon ripstop material sewn in the middle), then cutting both sides without moving the skin. The reason? If you offset the skins, it is too easy to overcut the split skins and end up with less-than-wall-to-wall coverage due to the nylon flexing.
Black Diamond's instructional video for cutting their skins:

Shop Black Diamond Climbing Skins

G3 Tips 

  • The G3 cutter separates the skin from the ski base with a wedge as you cut and can sometimes stick on the skin adhesive as you push it, which may cause a jerky motion and inconsistent cut. The key is keeping the gap between skin and ski consistent as you move down the ski. 
  • Keep the tool clean by wiping it with citrus solvent or paint thinner between each cut (but be careful to keep the cutter as dry as possible when you’re using it as these solvents damage skin glue). 
  • It also helps to have a ski vise that will secure your ski on its side so you have both hands free when using this tool; you can precede the cutter with your fingers to keep the gap from opening too far and producing a wavy cut. If used properly, the G3 cutter gives you a great result with an offset that’s perfect for wider (~2.5 mm) edges.
Shop G3 Climbing Skins

K2 Tips  

  • The K2 cutter also produces an automatic, slightly narrower offset of about 2 mm. It’s not totally obvious how to use the tool, even if you’ve cut a lot of skins, so read the instructions before you start. 
  • The K2 tool doesn’t drive a wedge between the skin and ski like the G3 tool, but it’s still much easier to use if you have an upright ski vise and can run a finger ahead of the cutter to hold the skin close to the base.
Shop K2 Climbing Skins
 
Note: Both the K2 and G3 cutters are hard to start on a shallow angled cut (like at the tip when the skin is slightly narrower than the ski) since they don’t push the skin down securely. If you have trouble getting the cut started, try using a razor blade for the first ½ inch or so, then switching to the cutter.

If you run into trouble and end up with a poorly cut or wavy edge, you can smooth it out by moving the skin over to a cutting board or other clean, hard surface and re-trimming it with an X-ACTO® knife and metal straightedge. Tapering the skins at both tips and tails is a good idea to keep snow from building up at the ends – this can often be accomplished best with a pair of stiff, sharp scissors. Clean tools afterwards with citrus solvent, but keep the solvent away from your skins.

That’s it, you’re done, it wasn’t that bad, now go skiing! (Well, skinning then skiing!)
 
We recommend taking an avalanche safety course to familiarize you further with all your backcountry gear.
American Institute for Avalanche Research and Education // American Avalanche Association // Northwest Weather and Avalanche Center

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Learn more with our other Backcountry Guides:
Backcountry Basics – How to Get Started
Backcountry Gear – Checklist
Backcountry Backpacks – How to Choose
Avalanche Beacons / Transceivers – How to Choose
Avalanche Shovels – How to Choose
Avalanche Probes – How to Choose
Avalanche Airbags – How to Choose
Alpine Touring Skis – How to Choose
Alpine Touring Ski Boots – How to Choose
Alpine Touring Ski Bindings – How to Choose
Dynafit (Tech) Bindings – Getting Started
Backcountry Basics - How to Skin
Climbing Skins – How to Choose
Climbing Skins – Size Guide
Climbing Skins – Weight Chart
Outerwear & Layers – How to Dress for the Backcountry


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