How to Replace Laces on Nucleo High II and Mountain Running Shoes

Start with the right replacement pair

Worn laces fail at the worst moment—usually mid-trail or halfway up a boot pack. Before you thread anything, confirm you have the correct replacement for your specific La Sportiva model. The Nucleo High II GTX Hiking Boot and the Mountain Running® line use different lace systems, so the right pair depends on which shoe you are relacing.

Both replacement options below are original La Sportiva laces sold by the pair, so you are not mixing generic cord with a precision lacing system.

Match the lace to your footwear

• Shoelaces-Nucleo High II: Replacement shoelaces for the La Sportiva Nucleo High II GTX Hiking Boot. Includes replacement clasps for the fast lacing system. If you own the Nucleo High II GTX, this is the model-specific pair—and the included clasps mean you can refresh the fast-lacing hardware at the same time.

  

• Shoelaces-Mtn Running (107 cm): Replacement shoelaces compatible with La Sportiva Mountain Running® Footwear. Sold as a pair. Choose 107 cm or 132 cm based on personal length preference and length averages. Mountain Running shoes use a different lace than the Nucleo boot; this pair is the compatible option and comes in two lengths.

  

Choose the length before you cut the old lace

For the Mountain Running laces, you have two lengths: 107 cm and 132 cm. The catalog notes that lengths are approximate and may vary slightly, and that you should choose based on personal length preference and length averages. If your current laces leave long tails after tying, the shorter option may suit you; if you like extra length for a generous bow or a double knot, the longer one is the safer bet.

The Nucleo High II laces are sized by boot size rather than centimeters: 54 in fits sizes 39–41.5, and 56 in fits sizes 42–44.5. Pick the range that matches your boot size. If you are between ranges, the catalog does not provide a half-size bridging recommendation, so use your best judgment based on how much tail length you prefer.

Relace the Nucleo High II GTX with its fast-lacing clasps

The Nucleo High II replacement set includes new clasps for the fast lacing system. The supplied information does not include a step-by-step clasp installation guide, so the following sequence covers the lace replacement itself; treat the clasp swap as a separate check against your boot’s existing hardware.

1. Remove the old laces: Unthread the worn lace from the eyelets or loops, keeping note of the path so you can mirror it on the new lace.
2. Check the clasps: The replacement pair includes clasps. If your current clasps are damaged or missing, swap them now; if they are intact, you can keep them as spares.
3. Thread the new lace: Follow the same path as the old lace, starting from the bottom and working upward. The 54 in and 56 in lengths are matched to boot size ranges, so the tails should be proportionate once threaded.
4. Tie and test: Lace up as you normally would and check that the ends are long enough to tie comfortably. The catalog does not specify a required tail length, so adjust based on your own preference.

Relace Mountain Running shoes in 107 cm or 132 cm

Mountain Running footwear uses a straightforward lace path. The main decision is length: 107 cm or 132 cm. Because lengths are approximate, treat the first lacing as a fit check rather than a final cut—there is no cutting involved, but you want to confirm the tails feel right before you commit to a knot style.

1. Pull the old lace: Remove the worn lace and note the eyelet pattern so the new lace follows the same route.
2. Pick your length: Choose 107 cm for a shorter, tidier tail or 132 cm if you prefer more length for a double knot or a looser tie. The catalog lists both as approximate.
3. Thread from the bottom: Work the new lace through the bottom eyelets first, then follow the original path upward.
4. Tie and adjust: Tie as usual. If the tails feel excessive, you can rethread with the shorter length; if they are too short to tie comfortably, move to the longer length.

When to replace rather than re-tie

Replace laces when you see fraying, flattened spots, or a core that feels stiff or brittle. A lace that has lost its shape will not hold tension evenly, which can make even a well-fitting boot feel loose. The Nucleo High II set also lets you refresh the fast-lacing clasps at the same time, so it is worth inspecting those whenever you change laces.

For Mountain Running shoes, the 107 cm and 132 cm options cover the two common preferences, but the catalog does not list a size-to-length chart. Use your current lace as a reference: if it measures close to one of these lengths and ties well, stay with that length.