I put mine in my camelbak. It reaches perfectly to the top "phone" pocket. I could also use an extension cable from my other light systems and run it anywhere else I need to, but then I wouldn't have the ability to screw them together (the fittings work, but the ability to screw is not present in older cable - it still snaps together nicely though). but in the camelbak works nicely.Question for you all: with the light on my helmet, uh, where is the battery supposed to live? Do I get a cable extension and put it on the bike? Strap it to my arm? The back of my helmet? It seems like it'd reach down my back but not much farther.