Merrell MQM Flex 2 Mid GTX Women's review: a versatile hiking boot and trail runner hybrid

The future-forward Merrell MQM Flex 2 Mid GTX is a second generation of its MQM style, gearing up to be a serious trail runner and hiking boot hybrid with a new and upgraded spec. A multi-level activity boot, whether hiking, trail running, scrambling or climbing, the Flex 2 sets out to combine all the best features needed for an array of pursuits, into one protective, proactive boot that's worthy of our best women's hiking boots guide. The shoe version also sits in our best women's walking shoe guide – head to our Merrell MQM Flex 2 walking shoe review for more on that one.

Update: as of summer 2022, the Merrell MQM Flex 2 range has been officially replaced by the Merrell MQM 3, also available in a shoe or a boot. 

Merrell MQM Flex 2 Mid GTX Women’s review: Design

Launched in Spring/Summer 2020, the MQM Flex 2 Mid GTX keeps a similar look and feel to its predecessor, but with some key functional updates. The rubber outsole has been upgraded to the Merrell mountain-grade Quantum Grip, increasing the lug depth to 5mm, for improved traction. It also features a braking section at the heel, to enhance stability on steep descents. It boasts two types of multi-directional cleats to support grip and give stronger traction. 

Another important new feature is its enhanced water-tight and weather-proof experience. It uses an InvisibleFit Gore-Tex – one continuous piece of material, to avoid any seepage or damp penetration through seams. And, working in synergy with that waterproof mesh on the upper, the bellows tongue is perfectly designed to keep out any debris and lock the foot in place comfortably. The tongue is also integrated with the smart lacing system, for ease of adjustments and any necessary fit fine-tuning.

Focusing on protection in the rear foot, true to its previous model, the Flex 2 has a robust air cushion in the heel for shock-absorption, stability and to ensure the foot is correctly aligned regardless of the pace or incline. Continuing that protective theme, the midsole features a rock plate to shield against sharp surfaces, while the dual-direction flex-grooves enhance that ground connection with each stride.

Weighing in at a slightly increased weight at 708g for men’s (from 648g in the original) and 580g for women’s, it still retains a very lightweight, agile, glove-like feel and stays middle of the pack in terms of its competitors’ weights.

A standout feature is that unlike its original, the 2.0 Flex is 100% vegan-friendly, making it a more inclusive and ethical choice all round.

Merrell MQM Flex 2 Mid GTX Women's review: Performance

The boots do run a little warm thanks to that Gore-Tex and would be better for winter/fall or colder climate adventuring because of this. Merrell does a non-waterproof version that would be better suited for hotter hikes. Due to the Gore-Tex, the uppers take a little longer to dry out once they’re pretty saturated.

Putting the Flex 2 through its trail-blazing paces was something of a challenge during lockdown, but fortunately, I found a few decent terrain types to take it for a test run. On first impressions, this boot had me at out-of-the-box comfort. Several hikes in, they maintained a blister-free record – that is key for me as I blister very easily, particularly breaking in new boots.

The cushioning and comfort levels were spot-on, and unlike sturdier leather boots I’ve hiked in (even trusty ones have been known to deliver an unexpected blister or two), the trainer-like feel to this boot delivered an exceptional fit, as well as a deftness and dexterity with each step. But don’t let that lightness deceive you, the Flex 2 still packs plenty of protection via its rock plate, and when teamed with the cleats and air-cushioned heel, certainly delivers core stability and strength.

Also supporting the comfort and stability is the Kinetic Fit Base insole, which is perfectly contoured giving the foot extra traction and keeping it securely in place. Helpfully, it’s also removable, so if you want to swap it out with an insole that’s better ergonomically shaped for your foot, you have that option too.

Navigating through slippery terrain, that braking section at the heel and increased lug depth really came into play, supporting a controlled and well-balanced downhill descent with no major issues. The protective TPU toe cap also helped with protection and grip on looser ground. The waterproofing of that seamless Gore-Tex was another strong feature, as was the bellows tongue, which all combined to keep my feet comfortably dry and free of any debris – even on a particularly wet and soggy outing.

Merrell MQM Flex 2 Mid GTX Women's review: Verdict

Built with speed and pace in mind, this boot errs on the side of the trail runner more than the heavy-duty hiker. But, for day hikes, trail runs and light backpacking, it’s a super-strong option. Seeking to appeal to multiple activities, terrains and paces, it could run the risk of not being specialized enough. Certainly, if you’re a more technical hiker or scrambler, you’ll likely be looking for something more technical and focused, but for a generalist like myself, this boot nails all my needs in one.

It really delivered robustly in the grip, stability and agility stakes, as well as comfort and fit right off the bat. Looks-wise, it’s a pretty smart option in Granite/Wave with gentle pops of aqua, and after a muddy hike, thankfully it’s relatively easy to clean too.

Some reviewers have stated that the sizing runs a little larger, so if you’re a half size you may want to size up by another half to ensure the best fit. Check out their measurements and match it up to your most comfortable pair.

Coming in at $160, the Flex 2 is great value in terms of the scope and spec you get for that and compared to its competitors is in the mid-range.

Merrell MQM Flex 2 Mid GTX Women's review: Also consider

If you’re looking for a more sturdy hike-centric boot, the Vasque Breeze AT GTX is a great option, complete with excellent traction and a breathable design, ideal for warmer hikes. 

Coming in a little under budget compared to the Flex 2, the Salomon X Raise Gore-Tex at $130 is an excellent shoe option, focusing on stability, comfort, and performance. 

If you’re looking for a super-specialized trail shoe designed for speed and dexterity, the award-winning Inov-8 Terraultra G 260 features a graphene-grip rubber and cushioning foam for elevated traction across multiple terrains.