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Merrell Mix Master Aeroblock Review

Posted by on Aug 23, 2012 | 7 Comments

The Merrell Mix Master Aeroblock (MMAB) is similar to the Mix Master 2 (MM2) with a different upper. This shoe was one of three pairs I brought along for the grueling TransRockies six day stage race in Colorado (the others were two pairs of Merrell Trail Gloves). Needless to say, the shoes were tested in extreme conditions.

First Thoughts

Aesthetically, I prefer the Aeroblocks to the Mix Master 2’s, which I’ve also tested extensively. Merrell’s design teams are finally busting out of the “outdoor industry” muted color schemes and making shoes that truly stand out. The Aeroblocks are an excellent example of this.


As far as fit, the shoes are nearly identical to the Mix Master 2’s. The shoe is made from a different last than the Barefoot lineup, so it’s shaped more like a traditional shoe. I have mixed feelings about this. On one hand, it provides more protection for the toes. On the other hand, it doesn’t quite allow for as much foot movement within the shoe as the Trail Gloves. It’s a trade-off I gladly make due to the protection afforded by the MMAB’s, but this shoe would be perfect if it were made on a Trail Glove last.


The heart of any trail shoe is the sole. A good trail shoe must provide aggressive traction in a variety of conditions but not be too aggressive to the point where it collects mud. This is where the MMAB shines. The sole works exceptionally well in every mountain terrain I encountered- dirt trails, rocky trails, skree, water crossings, wet rocks, mud… you name it, the MMAB conquered it. I was especially impressed with the traction on wet rocks. A part of the TransRockies trail followed a stream- you literally ran down the stream for about a half mile. The water was anywhere from 6″ to a foot and a half deep covering smooth rocks of various sizes. Most people gingerly walked this section. I was able to bomb down it at a 5:45 minute/mile pace (about as fast as I ever run).

The shoe offers excellent protection, which is exactly what I want in a mountain running shoe. The sole and rock plate are thick enough to disburse the impact of the sharpest of rocks, while still maintaining a fairly low stack height

The shoe has a 4mm heel-to-toe drop, which causes mixed feelings. It does help with bombing downhill, and does relieve some stress on the Achilles on steep uphills, but gets annoying on flat roads. Because of this,I use the MMAB as a specialty shoe for technical trail running on gnarly trails.


The upper is less ventilated than the MM2, which makes it more suitable for cooler weather. This was definitely a welcome addition when the temperatures hovered around freezing when standing atop Hope Pass. The shoe would definitely be a good choice for winter running. The negative- the shoe does not drain or dry as fast as the MM2. As such, I’d be selective as to which shoe I choose based on temperature and moisture- the MMAB for cool, dry conditions and the MM2 for warmer, wetter conditions.

Who Would Use This Shoe?

This shoe would appeal to a wide audience. Hard-core trail runners will appreciate the light weight and protection. Those living in the snow belt will appreciate the added warmth and water resistance. Fashionistas will appreciate the aesthetics.

The shoe may not appeal to hard-core barefoot runners that stick to sidewalks and asphalt bike paths. The ground feel isn’t nearly as good as a shoe like the Flux Glove (review coming soon) or Trail Glove, or most of the Five Fingers. Also, the more traditional shape of the last will feel odd to those accustomed to a more anatomical last.

For me personally, this shoe will be my go-to mountain running shoe in cooler weather. I’ll be using it at night at both the Grindstone 100 miler in the Blue Ridge Mountains of Virginia and the Chimera 100 miler in the mountains east of Los Angeles. I’ll also use this shoe for mountain running in snowy conditions.

Anyone else use this shoe? Tell me about your experiences in the comments section!


This shoe was provided by the manufacturer.


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  1. dogrunner
    August 27, 2012

    Any hope of wide size versions of the MM2 and MMAB?
    The standard trail glove is too narrow – the forefoot width on the wide TG is great (sloppy heel fit though).
    If the MM2 and MMAB are not available in wider sizing, they won’t fit me, however appealing they are otherwise.
    Hoping, but not expecting…

  2. Stefan
    August 24, 2012

    Actually, I wanted to try these shoes but was hesistant initially. Your review made me definitely not to get these shoes. I think instead of throwing another 4mm slightly too narrow trail running shoe onto the market (there are already that many options now), Merrell could have really differentiated itself by developing some Bare Access – Mix Master mix.

    • Jason
      August 24, 2012

      The Bare Access/Mix Master combo (Bare Access for trails) is in the works. Unfortunately they couldn’t rush the development enough to get it out this season. It’s a sweet-ass shoe, though!

      • Stefan
        August 24, 2012

        This is great news. Next season? Is this 2013 or 2014 in shoe industry time scale?

        So I guess it will be Inov-8 Trailroc this season.

  3. Aaron
    August 23, 2012

    I don’t know about the Mix Masters. My feet slide forward too easily on a decline, no matter what I do with the lacing, which results in some uncomfortable toe jamming. The fit in the trail glove and road glove both did a good job of holding my foot in place, so I was a bit disappointed.

    • Jason
      August 24, 2012

      The last of the Trail Gloves works much better for me, too, but the MM2/MMAB offers the needed protection for mountains… especially at night. Needless to say, I’m eagerly awaiting the next generation of Merrell’s trail shoes (see comment above). 😉

      • Aaron
        August 24, 2012

        For now this is it. But if the Altra Superior comes out before November I may use that instead. I’ve attempted the Ozark Trail 100 once with a thin sole, and that’s not happening again.