Originally Posted by cyccommute

I’m not sure you have the evidence to make the statement that a dirty chain increases drivetrain wear. The video shows that a dirty chain decreases power output by 1 W. The decrease is due to an increase in friction. Friction is a measure of the wear of the components. If a dirty chain significantly increases drivetrain wear, it would show in the decrease in the power output like that seen when they dropped sand onto the chain. The power output dropped in that case by 12W which is significant, although I would say that putting that much sand on a chain would be next to impossible even in the wettest ride.

I’m not advocating for riding around with dirty chains. There are other reasons not to do that but obsessing over chain and drivetrain cleanliness is a fool’s errand.