On the oldroads.com / vintage lightweights forum, I posted a tip for salvaging a crank with a worn spindle eye: grind a couple of mm off the back surface, around the spindle eye, to restore clearance with the BB cup. That was last week's problem with my PKN-10. This morning, when I got to my destination and started to lock up the bike, I noticed some torn cords in the rear tyre sidewall, and the first hints of a telltale bulge. The tyre is a 700Cx28 Specialized Armadillo Turbo, probably close to 4 years old. Not wanting to take any chances, this afternoon I bought a new Continental Ultra 2000 for the front, and moved the front tyre, also a Specialized Armadillo, to the rear. I also found the source of my annoying and disturbing drivetrain click and pop sound: one of the rollers on my chain had either worn or broken off, so that the inward protrusions of the inside link plates were contacting the chainring and cog teeth. This is the first time I have ever encountered this problem, and I am trying to figure out the failure mechanism. My best guess is that this particular roller seized (or perhaps never did turn freely) and gradually wore down, until it broke, but this sounds a bit unlikely. I have been using White Lightning or RaceDay; is the lubrication inadequate?