When it's warm enough to not have any covering on his legs he always notices his knees, looking for that slight irregularity in the pedal stroke. Where that leads, tendonitis? Worn out too soon meniscus? All of it runs on a loop in the head, the wind and the cars, the trees and the trail isn't enough to distract the formation of doubt. The creation of problems that don't yet exist. Though they grow, steamroll, snowball into the invisible 400 pound gorilla.