Over the past months my rear sprockets have accumulated a fair amount of gunk == chain oil + dirt + sand + hair + grass + wood chips. They look bad, and furthermore I fear the chain might be picking some of that up. I know there are specialized brushes and solutions for that, but I haven't tried them yet.
Are they effective? Are there any alternatives?
Note: the necessity of such an intervention is another topic. I've ridden for decades without performing it and have been perfectly fine.
This is most certainly a duplicate of something, but I just can't find it. Moderators: merge away!