Chain keeps falling off my Kilo. I'm using a Shimano 600 crankset to a... BB with a short spindle? Bike shop first said it was because I was mating the wrong chain width to the chainring, and then it was because I wasn't giving enough tension to the chain. Got the appropriate chain, and got rid of the slack. It still comes off when the tension goes. I never had a chain fall off because it was "too" slack in my previous builds. They said the BB looks fine. Thoughts?