I hope my story of chain woes is not in some part responsible for your worries. I think my problem came about because I developed a bad habit of "cross chaining" on my hybrid,which was very forgiving and never ever dropped her chain. Not sure why, I guess I just didn't know any better at the time. I also have a bad habit of waiting until I'm in trouble on a hill and then shifting to the grannie gear in a panic with too much tension on the chain. Since you've always been chainless, it is unlikely you will have developed the same bad habits. If worse comes to worst, I have discovered there is a handy little gadget called a "chain keeper" which is like a little plastic thumb, poised right by the grannie gear which nudges the chain back where it belongs should it start to fall off. Hubby installed mine monday and we tried several times to MAKE the chain fall off and it wouldn't. (I will still try to improve my shifting habits, but it's a nice bit of insurance...)