“When the foot is in motion the forefoot compresses, which when combined with overlaying materials typically used in conventional boot construction, creates flex points that not only consume energy, but also can lead to premature failure of boots in this area”, explains Selim Say, product line manager at Keen. “The addition of the accordion-like Keen Bellows Flex technology to this critical area enables hikers to move with less effort, leading to easier days on the trail and many more miles of comfortable performance during outdoor adventures.”

“It features recycled PET throughout the protective rand.”

Improved durability is said to be another key aspect of this new technology. Footwear can often crease and crack at the top of the footbox, as this is one of the most heavily used flex points of a boot and an area commonly prone to wearing out due to repeated bending. The durable yet flexible TPU insert has been engineered to solve these issues, reducing signs of wear and tear.

Keen’s new Bellows Flex range, due to be released in February, includes two new styles premiering for Spring/Summer 2021: the Ridge Flex WP and Tempo Flex WP, with both available in a mid and low cut. The Ridge Flex is the stronger and sturdier option, designed for bigger mountain days. Ultimately it’s a little like Keen’s much-loved Targhee boot, with the bellows inserts added in. It’s constructed from premium leather (with ethical credentials), with a DWR treatment to the upper and a Keen Dry membrane for maximum waterproofing. A speed lace system allows for a precise and snug fit, whilst a heel capture system and underfoot shank ensure reliable stability and protection on technical terrains. The design is finished with the TPU Bellows Flex insert at the forefoot (and at the heel in the mid option), as well as a Keen All Terrain outsole with rugged 5mm lugs for good traction. The Ridge Flex costs £150 for the mid and £140 for the low-cut model and is available in both men’s and women’s editions.

The Tempo Flex WP (mid £130, low £120) is a more agile option, with a stylishly-contemporary, sneaker-inspired look and bright colourways. This fast and light hiker features a performance rip-stop mesh upper with TPU overlays for durability and Keen Bellows Flex insert to make every step on the trail easier. You also get the Keen Dry waterproof and breathable membrane, grippy All Terrain outsole, speed lace webbing system and underfoot stability shank. For added eco credentials, the Tempo Flex also utilises recycled PET throughout the protective rand to the side and front of the shoe for extra durability.

For more information visit keenfootwear.com