I have a MTB whose old chain actually broke under stree a couple summers ago while I was showing off in front of my kids. Not a major FAIL but I had to walk it back to motel. It was the end of the ride on the last day of our trip. I tried to whip out my chain tool and do a field repair redeeming myself in my kids eyes, but alas I failed again by not having it with me that day. (naturally, right?)

I have a hybrid with the same # of speeds whose chain I replaced prematurely with new and have been saving the still good old chain. I intend on trying that chain on the MTB and I expect it will work just fine.