4 min read Welcome to Trail Tested , a new monthly column from entrepreneur and athlete Jack Espy as he trains for the grueling Leadville 100 ultramarathon this August. Trail Tested will follow Jack along his journey to do his first 100-miler to see what his body is capable of and what his mind can endure. Throughout his training he’ll be giving us a rundown of gear he’s been putting to the limit. HYDRATION IS A crucial factor for anything longer than a 5k, and that’s intensely magnified for a 100-mile race. And there’s really no way to know what you’ll want on your person except by putting in some seriously long miles. I’ve been doing just that with my training, and trying lots of different setups and methods for long training runs and races. What I’ve found is a capable, adaptable, and versatile hydration vest in the Salomon S/Lab Ultra 12 Vest . And it might just be the foundation of my race day kit.…