We rely on Marginal Gains listeners to provide intelligent and provocative questions, and as always, our listeners do not disappoint. In this Ask Josh Anything episode, we re-open the question of hour record attempts, this time considering pros and cons of a negative-split effort. We talk about Nitrogen and its merits of using it instead of air for tires with sealant. We talk about the aerodynamic penalty of tucking your glasses into your helmet vents. Plus tire temperature talk, cyclocross marginal gain tips, and why most BMX bikes don't race tubeless.