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Fit and sizing

Surgeon's knot

Also called double-wrap lacing, heel lock

What is a surgeon's knot?

A surgeon's knot is a lacing trick where you wrap the laces twice instead of once before pulling tight. The extra wrap holds tension in place, letting you lock your heel down while leaving the toe box loose.

Surgeon's knot at a glance

Where to tie it
At the eyelet nearest your ankle bend
Takes
About three seconds
Fixes
Heel lift and downhill toe bang

Why ordinary lacing loses tension

Ordinary lacing leaks tension. You pull the lower section tight, move up to the next eyelet, and by the time you tie off, the tension has redistributed itself evenly along the whole boot. That's fine on flat ground and useless when your heel is lifting on a climb.

How to tie it

The fix takes about three seconds. At the point where you want the tension to stop moving, usually the eyelet at the top of your instep, cross the laces and wrap them around each other twice rather than once before pulling. The double wrap binds, and everything below it stays exactly as tight as you set it.

What it fixes

This is the standard answer to heel lift, which is the mechanical cause of most heel blisters. It also lets you run a boot loose across the forefoot for swelling and tight around the ankle for a descent, which is a combination normal lacing can't give you.

What this means when you're choosing

  • Round laces, which hold a double wrap better than flat ones
  • A boot with enough eyelets to place the knot where your instep actually is
  • Whether the boot has locking or hooked eyelets, which do a weaker version of the same job

The common mistake

Fixing heel lift by tightening everything

The instinct is to haul the whole boot tighter, which crushes the forefoot and does very little for the heel, because the tension migrates. Two surgeon's knots, one at the instep and one at the ankle flex, solve it without touching how the front of the boot fits.

Common questions

Where should I tie the surgeon's knot?

At the eyelet pair sitting over the highest point of your instep, which is usually where the boot flexes as you walk. If your heel still lifts, add a second one at the top of the ankle cuff.

Will it damage my laces?

It wears them a little faster at the wrap points, and round laces handle it better than flat. Laces are the cheapest part of a boot, so this is not a reason to skip it.

Where this comes up

Guides on Tom's Hiking where surgeon's knot changes which product is right for you.

More in fit and sizing

Torso length

Torso length is the distance from the bony bump at the base of your neck down to the top of your hip bones. It's the measurement backpack sizes are built around, and it has almost nothing to do with how tall you are.

Iliac crest

The iliac crest is the curved top edge of your pelvis, the ridge you feel when you put your hands on your hips. It's the shelf a backpack hipbelt sits on, and the lower anchor point for measuring torso length.

Last

A last is the foot-shaped mould a shoe or boot is built around. It sets the width, the volume, the shape of the toe box and the heel cup, which is why two pairs in the same size from different brands can fit completely differently.

Toe box

The toe box is the front of a shoe, from roughly the ball of the foot forward. Its width and height decide whether your toes can splay under load, which is what stops black toenails and blisters on long descents.

Gusseted crotch

A gusseted crotch is an extra diamond or triangle of fabric sewn into hiking pants so four seams do not meet at a single point. It spreads the load of a high step across several seams, which is why gusseted pants do not bind or split at the crotch.

Short liner

A short liner is the brief, boxer or compression layer sewn inside running shorts and worn instead of underwear. Its cut is what decides whether long runs chafe: a brief covers little, a boxer liner reaches the inner thigh, and a 2-in-1 anchors to the shell so it cannot ride up.

Inseam

Inseam is the length of a garment's inner leg seam, measured from the crotch to the hem, and it is how running shorts are sized. Trail shorts run from about three inches to nine, and five to seven covers most trail running.

Chafing

Chafing is skin worn raw by repeated friction, usually where wet fabric rubs skin or skin rubs skin over hours. On a run it starts at the inner thigh, and dried sweat leaves abrasive salt behind that makes it considerably worse.

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