Can Finish Line 1-Step clean and lube your chain at the same time? Yes, but with a caveat. To get the best from it, you should begin using it on a thoroughly clean chain.
If you start with one that’s been drip lubed and ridden until it’s a solid black rope of links then you’ll use loads of 1-Step and not achieve a great deal.
A chain like that needs a scrub with a degreaser and brush before you use 1-Step. Because the 180ml aerosol doesn’t have much spray power, there’s a limit to what it can remove without you helping with a rag.
On a clean chain, it’s a different story. The spray does indeed lubricate, quieten things down and protect. When it gets washed off by rain or the chain gets dirty or muddy, give the links a quick blast and the 1-Step will clear away the dirt and any old remaining lube and recoat everything with a fresh layer.
Use 1-Step at the expense of other lubes and it begins to do what it proclaims it will on the tin. Do be careful about overspray hitting brake rotors, though. We missed the chain and nearly ruined our rear brakes.