Many of the best bike chain lube options claim to clean and lube at the same time. It's an excellent feature, and it works to a certain extent, but it's not the same as what the best bike chain degreasers do. Those claims are all about cleaning dirt off the chain as the lubrication is being added. From time to time, you'll want to completely clean the drivetrain. Getting all the old grease off along with the dirt and grime that's caked into it. For that, you want a true degreaser, not just a combination cleaner.