i think its due to the cog or chainring. when i ran the stainless phil cog i never had an issue, currently running a cheap steel cog and get rust spots on chain when leaving it wet. mmmm
for the third time, it's the salt they put on the roads, look at the manhole/drain covers in the dry, they have rust on them
for the third time, it's the salt they put on the roads, look at the manhole/drain covers in the dry, they have rust on them