bike wrench

If you want a non-hazardous (to humans) degreaser, d-limonene can be purchased food grade. It's just orange oil, has similar properties to kerosene, but is "generally recognized as safe" by the FDA and EFSA. Commonly found in liquid hand soap.

Basically, it's paint thinner you can drink.

It can also be used as an additive in petroleum based cleaners, in which case, definitely not a good idea to drink!

More to your question, I usually start with hot soapy water as a first pass, but it probably won't get your chain looking like new--need the degreasers for that.

I use an ultrasonic cleaner with some eco carb cleaner - similar to Simple Green. There are plenty of non-toxic and biodegradable degreasers on the market.

Bike degreaser + brush + possibly a flathead screwdriver to scrape off solid muck.

Expect to run it several times if the chain is in a bad state. It may be more practical to just get a new one, because cleaning those things can be quite a challenge, and being very dirty, they may just be worn to the point of needing a replacement anyway.

Should you choose to get a new chain, make sure to clean your other components before putting on the new one (chainrings/cassette/jockey wheels)

I like to take a small container with a lid, throw the chain there with degreaser and shake the container for a minute, then let it soak overnight

Then just flush it under running water and wipe dry -> add new lubricant

Most of the tips here make sense. I'll add on that hot waxing your chain if you have the option works well for where I live, and makes everyday cleanup much easier. A waxed chain picks up a lot less shit on it each ride since there's nothing to stick to, and you just lightly spray off then dry it with a towel to keep it clean. Not for everyone and every locality though, works for me in New England.

I had one of those gizmos that you can attach and run the chain through and the cleaner was sorta like orange clean. Never really looked at it closely but swear it seemed like it was orange oil.

WD 40 is quite good as a degreeser you can try to dilute it, other quite good chemical to try is ethanol or methanol (whatever is easiest to buy). Didn't tried anything bike specific but some kind of kitchen degreaser worked well too but it is usually some nasty mix with NaOH mixed in it (gloves needed).

Might want to consider wearing gloves in case there are any metal shavings embedded in the grease. I've neglected this before and found little steel shards in my hands for a week or so afterward.

Picked up "Gear Hugger ECO Heavy Duty Degreaser" at Target. It did a decent job, but the chain wasn't that dirty, and it took a couple of applications. They're carried in a lot of places like Walmart and Home Depot. They claim it's all plant-based. You want to make sure you lay down a lot of newspaper or a tarp. Makes quite a mess.

If the chain is really dirty, you'll want to take it off and soak it in a cleaning agent for a while to get into all the nooks and crannies. Also, the gear cassette and derailleur may be dirty too, but taking those off will not be as easy.

FWIW, the same brand also sells Dry Bike Lubricant.

No relation to them. Just found them after looking for something non-petroleum based.

@Wahots@pawb.social

I cleaned my bike chain a couple of weeks ago and it was caked in grease+dirt. First I used a flathead screwdriver to dislodge as much crust as possible, then an awl/pick to get into smaller spaces then I used hot soapy water + eco/biodegradable dish soap + stiff brush. I scrubbed the chain while it was on the bike then I removed the chain (and rear mech and cassette) and scrubbed them all again.

After I dried them all using a towel then sprayed with WD40. Allowed this to evaporate, sprayed them with EPA, then greased them all with lithium grease spray.

I disassembled the mech, cleaned all the individual parts the same way, then used lithium grease on the pivots and bearings. reassembled, refitted, and it's all running like new.

I probably could have used some bike degreaser however I didn't have any and couldn't be arsed going to buy some.

I usually do this with a specific degreaser, but once or twice I used soap and woter and it worked very well. Just make sure to use a dry cloth on your chain to avoid rust and after a few hours grease it again.