Overboot Fitting 101

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Submission by Andy Souder in the gear department.

Double boots are a great step-up from single boots for high-altitude expeditions. They aren’t sufficient for all environments though. Places like Denali and Vinson are often too cold even for double boots! You have two routes depending on your budget, goals, and fit needs:  

  • A “triple/8000m/all-in-one” boot such as the La Sportiva Olympus Mons/Scarpa Phantom 8000. This is a great route if you have the budget for an 8000m-rated pair of boots in addition to double boots, or plan on spending a lot of time above 6000m. These are also a great option if your feet run cold, or if you want one less piece of gear (the overboots) to manage each day. Read more about when a triple boot is preferable to a double boot/overboot combo here 
  • Double boots plus Overboots! The reason we’re all here today. This is a great option for those that don’t want to drop an extra $1300 minimum for triple/8000m boots, folks who don’t plan on objectives higher or colder than Denali, and those who want a more versatile boot system for a wide range of temperatures. This does make for one more piece of gear to manage, which becomes increasingly difficult with altitude, but not being stuck in a hot 8000m boot while descending from basecamp on the West Buttress can be a relief in warmer temps. It is important to note that this system does not provide the same level of warmth as a triple boot and is thus not appropriate for climbs like Everest or Cho Oyu. 

There are three crucial pieces to start with when fitting this system: your boots, the overboots, and your crampons of choice. Generally a full-strap crampon such as the Flexlock binding on the Petzl Vasak   is the best option. They work with the double boot and overboot system, require no additional modifications, and generally work with all other mountain footwear. The main downside here is that they take a little longer to get on and tend to be slightly heavier than the automatic or semiautomatic binding styles.  

If you have a beloved pair of auto/semiauto crampons that you want to make work with overboots, this next part is for you. Since the neoprene and rubber covers the welts on the boot, you have a significantly weaker connection between boot and crampon. To prevent unexpected releases, you’ll need to cut access for the lever and bail. To minimize the work to the overboots, we recommend staying with semiautomatic crampon bindings like the Black Diamond Sabertooth  If you are set on an automatic, we’ll cover the additional steps for the front.  

Tools you’ll need:  

Step 1:

First, measure the length of your boot sole to determine the correct overboot size. For reference, we are doing this demo with a size 43 La Sportiva G2 Evo, and Med Forty Below overboots.  

Overboots
Quick tip: Don’t size up the overboots if you’re in-between sizes. The neoprene will stretch a reasonable amount.

Step 2:

Put overboot on boot. They should be snug all around, be sure to align the seams at the toe and heel with the center of the welts.  

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Step 3:

Put crampon on boot. Snap the lever into the heel welt. You should not need to adjust the size of the crampons to accommodate the overboots – they should be fitted to the boots. It will create a nice dent when you remove the heel lever.  

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Step 4:

se a pen to mark where you need to cut, then use a razor to slice the heel. Its easiest to create a slice, remove the overboot, then go back with scissors to clean up.

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Step 5:

Cut out a thin rectangle (about an 1/8″-1/4″ tall and approximately 2.5″ wide) with scissors, careful to not cut the stitching. If you’re taking the overboots on and off frequently with the seams cut, it is very easy to rip the overboot in half!  

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Step 6:

Use duct tape to cover all the edges while still leaving the hole exposed. The goal is to reinforce this weakened area of the overboot and prevent fraying and rips. A thin strip for the top and bottom is usually sufficient.

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Step 7:

If using a metal toe bail rather than a front basket, repeat steps 3-5 in the front. Automatic crampons are not recommended with overboots due to the delicate fit required. Snow buildup could prevent the front from securing properly, and having a slice in the front also allows for more potential snow/water penetration at the toes if you are kicking steps. 

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Step 9:

Put crampon back on to ensure everything fits and is secure. You should hear an audible snap when attaching the heel lever as it connects to the heel welt on the boot 

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Special Considerations:

  • Congrats! Your overboots are Denali-ready. This system is great for versatility, but it does come with its own set of challenges. By modifying the toe and heel, it is now a weaker system.  
  • Be careful taking the overboots off. As mentioned before, being too aggressive can lead to the heel ripping further than you want.  
  • The neoprene is not particularly puncture-resistant, so proper footwork is crucial when using these. Stumbling and poor balance can lead to you puncturing an overboot with the opposite crampon.  
  • By modifying the overboots, you will be voiding the warranty. They might be able to be repaired for a fee, but you won’t be able to exchange them for another pair after your trip.  
  • Note that this modification is not required to make overboots work with automatic and semiautomatic crampons, but many find it necessary for a proper fit. It greatly increases the security of the crampon on the boot, but sometimes the overboots can be used as-is.  
  • Also check out our blog post on the decision between doubles with overboots and all-in-one boots, as well as the post on taking care of your feet. 

Overboots are a great way to boost the warmth of your double boots for bigger climbs without breaking the bank. They have their own pros and cons compared to a warmer 8000m boot. This is a helpful guide for folks looking to get a better fit with this particular system, but not a requirement for all. As with all gear questions, the Gear Department is always happy to help. You can give us a shout at 206-378-3688 or [email protected] if you’d like to discuss more. 

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