Keen Ridge Flex Waterproof Hiking Boots review




Hard-wearing hiking boots that offer all-day comfort, plus the added benefits of Bellows Flex technology

Pros and Cons

  • Comfortable for all-day walking
  • Offer plenty of support and protection
  • Waterproof and odour-resistant
  • Bellows Flex technology does work!
  • Top two lace eyelets could be further apart

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Footwear, Gear, Sponsored, Trekking Boots,

Chris Kempster tries out Keen's latest hiking boot which incorporates their innovative new Bellows Flex technology...

At Trek & Mountain we’ve reviewed numerous Keen hiking boots over the years, and they have invariably offered two things that any hillwalker or trekker wants from their footwear – comfort and durability. The roomy toe box that Keen are known for seems to suit a lot of people, and their chunky designs constructed from a mix of leather, rubber and synthetic materials means that both your feet and the boots themselves are protected from knocks and scraps on rocky or uneven trails.

The latest hiking boot from Keen, the Ridge Flex Waterproof Hiking Boots (to give them their full name), once again ticks all the boxes for what we expect from a Keen hiking boot – they have the roomy toe box, that distinctive rubber toe bumper, are made from a mix of materials and look as if they’ll eat long-distance hiking trails for breakfast – but with one important difference. This particular pair of Keen boots incorporate the company’s brand-new Bellows Flex technology, an innovative design idea that we reported on last month. But what exactly is Bellows Flex technology and – more importantly – does it work?

Bellows section clearly visible on top of boot

Bellows Flex technology

The Bellows.Flex technology that features on the Ridge Flex and its sibling, the Tempo Flex, came as a result of Keen’s desire to make a boot that enables the user to use less energy when walking. Keen figured that quite a lot of energy is used when your heel lifts and the front of the boot flexes, and that over a period of a few hours this energy adds up considerably. Making the boot flex more easily at the forefoot would save  a lot of this energy, but how to do it?

The design that they came up with also had the benefit of avoiding an age-old problem with some leather walking boots – the eventual cracking of the leather in the middle of the forefoot, where the boot bends when walking. Placing an accordion-like TPU section in the forefoot of the boot both makes it easier for the boot to bend, and simultaneously makes it less likely to fail even after years of use. Keen estimate that a hiker will use 60% less energy in bending the boot as opposed to a standard leather boot. There is also a smaller bellow-type insert at the heel of the Ridge Flex, and this flexes when the ankle is articulated, literally adding a spring to your step!

The ankle cuff is well padded for comfort and support


What about the rest of the boot? Well like previous Keen hiking boots, the Ridge Flex has a leather upper with overlaid synthetic panels at the front and rear of the boot, plus the trademark rubber toe bumper which wraps around the front of the boot. The lacing system uses fabric loops instead of metal eyelets for all but the top two sets, and there’s lots of padding around the ankles which results in a very supportive cuff section when laces are tied tight. Inside the boot we find a Keen.Dry waterproof liner and a removable PU insole, and the EVA midsole provides comfort and cushioning as well as stability via its shank. The Keen.All-Terrain outsole has a pattern of 5mm multi-directional lugs and, as the name suggests, is intended to offer grip on a range of surfaces from wet grass to gravel, as well as offer good braking on downhill sections.

Keen All-Terrain outsole worls well on a range of surfaces

In use

There were no surprises from the Ridge Flex during testing, with the fit and general feel of the boot being very familiar to us due to previous models that we’ve tested, such as the Targhee and Karraig. Although it’s a well-made boot that’ll stand up to rough trails and general abuse, the walking action is very easy due to the quite soft nature of the sole unit allied to the bellows flex feature. While we couldn’t put a precise number on the energy-saving properties of the bellows flex (let alone the 60% Keen claim) – we can confirm that the Ridge Flex feels light, comfortable and eminently capable of keeping your feet in good shape even after many hours of walking. Things we like about the boot include the well-padded ankle cuffs, which provide not just comfort but excellent support, especially when walking on uneven ground or going downhill. The midsole offers good cushioning, but not so much that you lose the feel of the terrain under foot.

In terms of niggles, the only issue we’ve had so far was some slight fiddliness when lacing the boots up, as the top two pairs of eyelets are located very closely together. We suspect that the eyelets have been positioned as they are to allow a really secure fit of the boot’s ankle cuffs around the ankles, so despite it taking a second or two longer to tie the laces that we’d have liked (so impatient to get out on the trail as we are!), it’s definitely worth it for the extra secure fit you get as a result.

The other thing worth mentioning about the Ridge Flex is that it’s not designed for scrambling. Of course it’ll allow you to do a bit of rock hopping without tipping you onto your head, but it doesn’t have the stiffer sole or stickier rubber that you would expect from a specialist scrambling/mountaineering boot. So if it’s more scrambling on rock than hiking on trails that you’re intending to do, you’ll need to look elsewhere!

The anatomic footbed cushions your feet as well as helping prevent them from smelling!


There aren’t too many significant innovations that come along in the hiking footwear market, and whether Keen’s Bellows.Flex technology proves to be a turning point in hiking boot design is probably too early to say. What we will say though is that the Ridge Flex does indeed seem to make flexing the foot easier (and thus save energy) and it certainly avoids the issue that leather boots can have of cracking at the point in the forefoot that the boot bends when flexed. Aside from the Bellows Flex feature, the Ridge Flex is an excellent all-round hiking boot, that offers support, waterproofness and odour-resistance to make one of the most comfortable boots you will find for all-day use on hiking trails and paths.

We’d certainly recommend trying these out before you buy (as with any boot), since although the Keen fit does suit a lot of people it won’t suit everyone  – however, aside from this we have no reservations recommending the Ridge Flex as an excellent choice of hiking boot, whether hillwalking in the UK or trekking overseas.

The Ridge Flex comes in three different colourways for men and women, and also comes in a low version priced at £144.99.

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