Many of us put on our helmets every day to go ride, but we never really think about how effective they're going to be at preventing traumatic brain injuries. That appears to be all John Lloyd thinks about; after testing hundreds of helmets, he's arrived at some fairly startling conclusions. He relates his study in this discussion with Mark and Wes Fleming, host of the podcast Chasing the Horizon. (Note: This is a lightly edited version of the discussion, which can be heard in full on Chasing the Horizon Episode 162.)