Originally Posted by patentcad
What's happening here is a cyclist chock full of steroids wouldn't pass this test every OTHER day and fail it only after Stage 17.
AFAIK, the recipe for cheating with steroids in cycling is to apply a patch to your scrotum after stages to help speed recovery. Letting you use small amounts when you need it, so that you don't step over the red line. You most definitely can pass 100 tests and fail one, if you either screw up, or somehow a reaction with something else happens (alcohool, cortizone, natural rush from winning?)
To answer another question on this page, the expectation for most riders is to have low testosterone levels after a difficult hill climbing day (bonk should be even worse, I'm guessing). That's why they need to top off levels.