There are 2 main methods to make climbing shoes: slip-last and board-last construction. Slip-lasted shoes are by far the most common today, with only a handful of manufacturers still producing board-lasted shoes.

The rule-of-thumb: Board-last construction creates a relatively stiff, supportive shoe and is reserved for flat, comfort-oriented kicks. Slip-last construction on the other hand can be used to create any style of shoe from a noodle-soft slipper to a morning-wood stiff high-top.

Although a flat and stiff shoe can be either board or slip-lasted, a soft or aggressively downturned shoe is the exclusive realm of slip-last construction.

The Last

Every climbing shoe is built around a hard plastic last (typically high-density polyethylene) that dictates the shape and overall fit of the shoe. The last is a mold that determines the heel width, instep height, forefoot width, toe box depth and shape, overall volume, and the degree of downturn and asymmetry.

Last shapes can vary greatly. The last for a flat, comfort-oriented shoe mimics the natural shape of the human foot. Conversely, an aggressively downturned, highly asymmetric last, can look more like an eagle talon than a foot. And each size of shoe has its own left and right last. The last shape is one of the most critical parts of the shoe design.

Lasts are also the most secretive part of a climbing company. This can be very frustrating for climbers because it makes it harder to know what the last shape is that best fits your foot. Some companies do share an overview of the last shape, and give letter abreviations to certain lasts.

Some companies use the same last for male and female shoes, which means the difference between the models will be minimal. Other companies have different shaped lasts for male and female models, and those shoes often fit larger and smaller volume feet better. SCARPA has one of the largest number of different lasts of any climbing shoe company we know about.

 

Climbing shoe last
A shoe last is the mold that creates the shape of the shoe

Slip-last Construction

With a slip-lasted shoe, the footbed is sewn onto the pre-assembled upper (the closure system and tongue) to form a sock-like shape. This sock is then slipped onto the hard plastic last (hence the name slip-last), which stretches the upper into the correct shape. Slip-lasted shoes then get a specifically shaped midsole to increase stiffness exactly where desired. The rubber rand and sole are then glued onto the upper/footbed assembly.

slip-lasted-shoe callouts
A slip-lasted shoe before the midsole, rand and sole are attached

After the shoe is designed and the last is designed/chosen:

  1. The pattern for each piece of material is created (based upon the specific last, design, and size of the shoe)
  2. Each piece of material is stamped or cut out
  3. The individual parts of the upper are assembled – this includes the upper material, the tongue, and closure system
  4. The footbed is sewn onto the bottom of the pre-assembled upper, creating a sock-like form
  5. The sock is then slipped over the last and laced up or velcroed tight (this is the step seen in the picture above)
  6. A layer of glue is applied (often using stencils) to the shoe where the sole and rand will be located
  7. The shoe is subjected to heat to prepare the glue for rubber assembly
  8. The rand rubber, including the tensioned heel rand, is stretched and pressed onto the upper
  9. If a molded heel cup is used (like on the Mad Rock Flash 2.0 in the video below) it is glued in place
  10. The shoe-stiffening midsole is attached to the bottom of the shoe
  11. The rubber sole (outsole) is applied to the bottom of the shoe, overlapping the rand
  12. The shoe is then subjected to very high pressure on all glued surfaces to ensure a solid glue bond
  13. The edges of the sole are ground down to create a square edge that is flush with the rand
  14. The bottom of the soles may be lightly brushed as a method to increase friction

Slip-last construction can be easily identified by the presence of stitching around the perimeter of the footbed on the inside of the shoe.

How to identify slip-lasted climbing shoes-01

 

To see the process in action, check out this video that shows the process of building Mad Rock’s Flash 2.o slip-lasted shoes:

Board-last Construction

Board-last construction is the traditional method of making shoes, including climbing shoes. It is not as common today due to the lack of versatility it offers.

In board-lasted shoes, the footbed is glued to the full-length midsole (the board). This midsole is then temporarily attached to the bottom of the last (the plastic mold) to keep it firmly in place.

Next, the pre-assembled upper is slipped over the top of the last. The upper is then tightly wrapped over and around the edges of the midsole and glued in place to make the midsole an integrated part of the shoe.

At this point, the shoe is in a similar state to a slip-lasted shoe: The upper is connected to a footbed, enclosing a last. The biggest difference here is the stiff midsole of the board-lasted shoe is what secures the footbed, while the slip-lasted shoe has no midsole (yet) and the footbed is sewn directly into the upper. The rand rubber and sole are then glued onto the upper/midsole assembly.

Board-last construction can be identified by the lack of stitching between the upper and footbed on the inside of the shoe.

board-lasted climbing shoe construction

A few examples of current (2015/16) board-lasted shoe models:

Butora_Mantra_Green_EE
Butora Mantra Green
Boreal_Equinox
Boreal Equinox
Boreal_balletgold
Boreal Ballet Gold

Although few climbing shoes are made using board-last construction these days, many other climbing-related shoes use this method, including approach shoes and mountaineering boots.

This video from Scarpa clearly shows the difference between slip-last and board-last construction with approach shoes, and it’s the same process for climbing shoes. We’ve queued the video to 1:06 where they detail the construction types. The video goes on to explain direct-attach construction (beginning at 3:03) which is not used for making climbing shoes.


Shoe construction extra credit video

If you’re curious about the arduous process of fabricating board-lasted, hand-made dress shoes, check out this video of custom-made Saint Crispin shoes (totally worth 15 minutes if you’re into handmade goods and processes).


Summary

Regardless of slip-last or board-last construction, climbing shoes are almost entirely made by hand. Yes, there are some steps that utilize machinery, but the critical parts of the process, specifically the tensioning of rand rubber, is completely done by hand, one at a time. At the upper end of the climbing shoe performance spectrum, this requires extreme skill.

Slip-last construction enables the use of a wide variety of midsole designs, from soft to stiff, minimal to full-length, and everything in-between. There are very few limitations as slip-lasted shoes can be shaped to any design.

Board-lasted construction requires the use of a full-length, relatively stiff midsole, leading to a stiff shoe. Board-lasted shoes generally last longer and can be re-soled more easily and more often than a slip-lasted shoe. The stiff midsole can be beneficial in many applications and is still utilized in shoes intended for crack climbing and all-day comfort.

Although we can draw some general performance rules-of-thumb knowing if a shoe is board-lasted (better for trad climbing vs overhanging sport/bouldering), there is significant overlap in the features and even the construction when compared with slip-lasted shoes. Ultimately, these construction types only refer to the process by which the shoe is made and are not a foolproof way to determine a shoe’s performance characteristics.

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Alison Dennis

Alison Dennis

Alison (she/her) runs WeighMyRack from her 17' travel trailer. She is currently touring the US and would love if you contacted her to meet up to talk about climbing, climbing gear, or if you have any fun and/or ridiculous adventure in mind.

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