1. An awkward name may be the J S3's only weakness. It has a perfect blend of agility and support: An airy top half made from a durable, ultralight mesh nylon keeps weight downand debris outwhile an innovative wraparound tongue provides an exceptionally secure fit.
2. Flexibility is key to the J S3's performance, thanks to cut-away channels in the EVA midsole. The result is an accordionlike pliability that allowed our feet to achieve a full range of motion. Testers felt noticeable spring as they bounded off even the gnarliest sections of Colorado's Dakota Ridge Trail.
3. The detached heel technology (called ForMotion, for those taking notes) effectively absorbs rear-foot impact, compensating for the foot's natural tendency to twist and roll when it hits rocks and uneven ground. "For such an agile shoe, it has a superstable platform," said one tester.
4. It's nimble enough to blitz hardpacked trails, but there's no compromise on underfoot protection for true mountain runningtesters suffered no stone-bruising, thanks to a protection plate. Even better: A tri-density rubber outsole with multidirectional lugs ensures that agility isn't sacrificed on technical terrain.
5. You'd have to put ice in your shoes to get better cooling. Breathability comes from above and below the foot, thanks to the meshy uppers and perforated, antimicrobial moisture-wicking footbeds. Caution: The air conditioning works so well you won't want these shoes in chilly, damp weather.
11.3 oz; adidas.com