Updates to Aku Tengu GTX

  • Aku’s Tengu GTX is an over-the-ankle boot ready for high-alpine ascents and climbs. Its upper is a made up of suede, nylon and a Gore-Tex laminate. This trio delivers weather protection and comfort on the trails.
  • Underfoot, the brand-owned Internal Midsole System (IMS) addresses stability and cushioning needed by users. It is partnered with a lasting board and Custom Fit Pro Alum insole to maximize performance.
  • Making this alpine boot bite on ground surfaces is a Vibram rubber outsole. Its wide indentations and pronounced lugs give it a self-cleaning ability.

Size and fit

The Tengu GTX caters to male mountaineers. It is available in medium (D) width and regular sizes. It fairly runs true to size. The Performance Fit last grants precision during climbs. Its traditional lace-up closure provides a snug fit.


The Aku Tengu GTX features the Vibram Curcuma outsole. Its aggressive studs are widely spaced to shed off accumulated debris, maintaining traction. The defined lugs at the toe area assist during climbs. The sole’s undercut heel maximizes the braking power of the boot, especially in steep descents.


Aku integrates the Internal Midsole System (IMS) to this model to deliver a shock-absorbing performance. It is a technology that forms the sole according to the anatomy of the foot.

This high-cut backpacking boot also grants a steady and comfy ride through its dual-density PU foam. The medium-density PU uses an Exoskeleton construction to yield stability and trail protection. The lightweight PU, on the other hand, is placed in the inner part of the unit to render cushioning and absorb ground impacts. There are toe and heel inserts which receive crampons.

A carbon fiber and die-cut EVA lasting board offers underfoot stiffness. A Custom Fit Pro Alum insole cradles the mountaineer’s foot while providing arch support and a decent amount of insulation.


To provide a durable yet flexible upper, Aku’s engineers designed the Tengu GTX with a combination of nylon and suede. Inside is a moderately insulated Gore-Tex Performance Comfort bootie which helps maintain a fresh environment through water protection and breathability. A Liba Smart PU rand wraps the lower part of the boot which protects it from scuffs and enhances its edging ability.

Its lacing system employs webbing loops and riveted hooks. The loop at the ankle area enables users to lock the heel in place (when tightened), preventing slippage. A pull tab is placed at the top of its elastic tongue for easy on and off.

Additional Info

  • This gear is compatible with semi-automatic crampons.

Facts / Specs

Weight: 725g
Cut: High cut
Features: Orthotic friendly / Removable insole
Waterproofing: Waterproof
Width: Normal
BRAND Brand: Aku
Material: Leather, Suede

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Paul Ronto
Paul Ronto

Over the past 20 years, Paul has climbed, hiked, and ran all over the world. He has summited peaks throughout the Americas, trekked through Africa, and tested his endurance in 24-hour trail races as well as 6 marathons. On average, he runs 30-50 miles a week in the foothills of Northern Colorado. His research is regularly cited in The New York Times, Washington Post, National Geographic, etc. On top of this, Paul is leading the running shoe lab where he cuts shoes apart and analyses every detail of the shoes that you might buy.