After a few years in rotation, the Nike ACG Mountain Fly has finally received an update and it's a big one. The ACG design team took all of the lessons they learned with the Mountain Fly, refined the approach and applied new thinking to create the Mountain Fly 2. Seen here in Low configuration, at a glance it's almost hard to see the similarities with the original Mountain Fly, with a full reworking of the concept. The novel lacing system of the original has been replaced with a more traditional spec with a toggle for quick adjustment. The rugged outsole remains, the updated tread draws inspiration from mountain bike tyres – providing traction across all manner of surfaces. The heel is rounded to help prevent irritation around the achilles, whilst the sock-like construction has been ditched for a more conventional tongue.