There are four flex grooves in the forefoot with the Rockstop rock plate exposed beneath and a midfoot flex zone. The shoe is still pretty stiff even with these flex grooves, but thankfully that does not take away from its great performance on the trail. Lori has 155+ miles (before the race) in this shoe on many different trails/terrain (wet/dry & rocky/buffed-out) and there is little-to-no sign of wear. Traction and ground feel has been great as well and the Hydrohesion is impressive in keeping feet dutifully stuck to the ground, even when wet.
The midsole is fairly cushioned (albeit a bit stiff but we’ll talk more about the flex in the RIDE section below, so read on!) and holds up well to rocks. The embedded Rockstop rock plate appears to be only in the forefoot and did well on all terrain without killing the ground feel. Finding a shoe that’s not too harsh or with too dead of a ground feel can be tricky – and certainly open to interpretation for each individual – but these seem to ride that line nicely
There was no noticeable break-in period for either of us and the 910v4 was good to go right out of the box.
The remainder of the shoe is a lot of bonded overlays from the midfoot, back which do well to support the foot on off-camber and more technical terrain.
Even with all of the overlays giving the shoe a bit of a “plastic-y” feel, it is very comfortable. There are generous amounts of foam around the collar and on the top of the tongue. This, along with the partial bootie construction gives a nice locked-down feeling to the foot. Over Lori’s 155+ miles, she found no sign of wear apart from being just a bit dirty…and we all know that “dirty” = a good day on the trail.
As we mentioned in the Intro, Lori chose this shoe for her last 50k (Deception Pass in Oak Harbor, WA). She needed a trail shoe that would be comfortable enough to go the distance and nimble enough to handle the slippery muddy, rocky terrain. Although feeling stiff, she found the cushioning of the NB 910v4 combined with the Rockstop plate & flex grooves gave a nice feel underfoot and allowed for a smooth easy feeling ride. Lori finished the race without any foot issues and has once again chosen the 910v4 for her next 50k (Terrapin Mountain in Sedalia, VA).