Drivverksrenser

Sprayed it straight onto my cassette and chain rings, let it sit a minute, and the gunk basically rinsed away. The spray nozzle gets right into the rear derailleur too, which is where I usually give up scrubbing.

Poured it into my chain cleaning device instead of spraying, and the gunk that came out after one pass honestly surprised me. Spraying the rear cassette directly afterward got the stubborn stuff off without much scrubbing at all.

The spray nozzle reaches the rear cassette without me having to take the wheel off, and the gunk basically melts off the chainrings. I also poured some into my chain cleaning device and it worked just as well that way.