I just came back from a downhill ride with a friend, who happened to lose his rear derailler pin, which was very unfortunate because there was no chairlift to take us back to the top. After spending about 10 minutes searching for the pin, I found a wooden golf tee and jokingly asked him if that would do, considering the similarity in size. After giving up our search for the actual pin, my friend wanted to try the tee just for the hell of it. So he jammed the thing in there and somehow it actually worked! He told me it performed better than his actual derailler pin. We both didn't think it would last another downhill run, let alone another long cross country circuit that we were planning on doing afterwards, but somehow it stayed in place the entire time, didn't move once, and my friend decided to keep it on his bike. I found it incredible that after riding at such fast speeds, down a very rocky trail with some small natural jumps along the way it stayed in there solid. So, maybe next time you go riding you might want to stick a tee in your camelback.