The Montrail FluidFlex ST is a comfortable lightweight shoe with just a touch of stability. It is similar to the original FluidFlex, with an interesting alteration in the midsole. The shoe touts itself as being a lightweight stability shoe, two things that generally do not go together. The shoe is very light at 8.8 oz. The FluidFlex ST uses Montrail’s FluidFrame technology, which is a mixture of different density foams that add the stability to the shoe.
The outsole is not a typical full-length tread that you see on a lot of trail running shoes. The rock plate is also very small under the ball of the foot and does not cover the heel area, which was definitely noticeable on rougher terrain. The tread is Gryptonite and can be found on other Montrail trail shoes. The diamond pattern of Gryptonite is located on the forefoot and the heel, but not in the midfoot of the outsole. Like its name implies, the Gryptonite gives decent traction on most surfaces, however, on very technical mountain trails it wasn’t as aggressive as I would have liked. It does seems to wear very well – with over 100 miles on the shoes, users did not notice much wear on the small Gryptonite lugs. The midfoot area of the outsole is the dual density Fluid Frame material. As expected, this did wear more quickly then the Gryponite, but helps lower the weight of the shoe.
The upper is constructed of a lightweight mesh that helps to keep the shoe light and fast. We put this shoe through some pretty technical terrain and did not notice any tears or holes after 100 tough mountain miles. Users were very impressed with the way the shoe held up to the abuse. The orange FluidFlex ST was a very attractive upper with seamless construction. It also dried very quickly after tromping through the snow and slush. The heel felt very snug and overall the fit was nice.
Overall, we were very impressed with this shoe. It was very comfortable and has performed very well on most of the terrain the testers ran. Most of our testers did not get any blisters or hot spots, however, two of our testers did find the heel collar to be a little to high, which aggravated an Achilles injury and caused another tester blisters.
The only other limitations were that the testers occasionally felt rough terrain through the heel and that the lack of Gryptonite in the midfoot area effected technical terrain performance. We were really impressed with the feel of the shoe and the improvements Montrail has made. This shoe is designed to be a comfortable, light, fast shoe with some stability, and in those areas it really performs.
TAUR Tester Feedback: Montrail FluidFlex ST
From our testers: Montrail FluidFlex ST