So hardened socket head cap screws survive fifteen years of hard service on my Tour Easy’s seat stay:
I replaced both screws with stainless steel 1-½ 10-32 socket head screws, with a reshaped head on the drive side, and we’ll see how long these last.
A few days later the continuing creak led to finding a broken gear clamp on the left side of the seat back:
Apart from the atypical lack of grime, you couldn’t tell that’s the replacement clamp, because the broken one looked exactly the same way. The clamp strap broke where it bent around the bottom edge of the seat pan bracket, probably due to the flexing caused by the broken seat stay screw.
Riding season is in full effect!
The Smell of Molten Projects in the Morning 