Ok, I posted a while back about possible BB noise, but I'm fairly certain it's not the BB. It's tight, and the noise is really intermittent. It seems to only happen in the evening, not the morning. It almost sounds like the click of the freewheel happens while pedaling forward. Is this possible? If my cassette is dirty would it make this noise?
It's a late 90s Schwinn Mesa GS - all original, not too many miles.