willydstyle

I'm in the process of bringing a new-to-me '79 Fuji America up to speed, and while I just straight-up replaced the chain due to extreme wear, I want to salvage the freewheel and clean up the chainrings. My problem is that they have built-up sticky, black gunk. I've tried cleaning them with soapy water, WD-40, scrubbing with a brass brush, but this gunk is just really tenacious.

Any tips on how to deal with it?

icepick_trotsky 

It's a good idea to replace your freewheel anytime you replace your chain. For the chainrings, try some degreaser like Simple Green.

bikemig 

Not exactly. There is no need to replace the freewheel if the chain has been replaced before it becomes too worn. If you run the chain for too long, the freewheel becomes worn and a new chain is likely to skip.

I'd replace the chain and clean off the freewheel. The cogs can be spun off using freewheel chain whips. The body of the freewheel will need some lube; I like phil wood tenacious oil. If the new chain doesn't skip on your freewheel, you're good to go. Otherwise replace as needed.

willydstyle

Sweet, my partner has a huge jug of simple green, I'll give it a go. I remember it leaving a residue, should I rinse with soapy water -> water afterwards?

dddd

Always use mechanical methods first when dealing with hardened and thicker layers of detritus.

I use a 6" metal rule for instance, applied to the rotating cogs, to strip out all of the crud.

A screwdriver tip similarly easily strips crud off of the rotating pullies.

The edge of a shop rag, pulled tight like a string, can be slid back-and-forth between cogs, forcing the freewheel to ratchet backwards in full circles for thorough cleaning.

A light spritz of WD40 on the rag edge area will provide needed dissolving power for a more scrubbed look if that's important.

I only use a solvent-diluted lube on my chain, so after a thorough post-application wipe-down, there is almost nothing visible to attract dirt and transfer oil to the rim, spokes, etc.
Best to apply the lube and do the thorough wipe-down after riding, so the solvent has time to dry, then the minimal remaining lube won't creep out and fly off.
A second wiping down of the chain is good after the first ride, if much lube has been squeezed out of the chain links from riding.

So I always spare the use of cleaners. I use a dampened terrycloth shop rag to do the remaining cleanup of the rest of the bike, starting at the bars and doing the dirtier drivetrain-are cleaning last, so as not to spread greasy dirt in the wrong direction.

You can't wipe too much lube off of a chain, and no lube should ever be applied to the sprockets.

noglider 

If it is very tenacious grime, you may want to use Krud Kutter or something similar. I've heard brake cleaner (for cars) does a good job, too. For the not-as-bad stuff, I use furniture polish.

likebike23

I've had good luck getting tenacious old grease off with PB blaster. To get between cogs I've used a piece of cardboard box followed by a folded over rag soaked in PB.

randyjawa 

I use a narrow scraper to scrape off most of the bulk gunk, between the cogs, right down to the hub of the freewheel. I then use a stainless steel wire brush and a gloved hand to hold the freewheel pressed to a wood surface (any non hard surface will do).

Vigorously steel brush the FW until it looks pretty good. Spray lightly with WD40, brush again, and repeat until it is clean as can you can get it. Results are pretty darn good, if you take the time to do a good job. That said...

Sometimes the cosmetics and tooth fit are shot. Then you replace what ever, as required.

mechanicmatt

superlube cleans crude pretty well

CycleryNorth81

Use carburetor cleaner to dissolve the gunk on your freewheel.

Replace current freewheel with a Sunrace freewheel if current freewheel is worn.

poprad

I might mention the use of heat, like a hairdryer or similar, prior to application of solvents and scrubbing. Heat does a great job softening up the gunk before you scrape it. I like a thick ziptie cut square instead of metal tools for scraping, if it's a nice freewheel or if you're not sure if it might just be aluminum (not unheard of but rare).

pastorbobnlnh 

If your freewheel is worth saving, oil on the inside is only a temporary solution. It really should be taken apart, completely cleaned, and then use grease.

This Regina CX looked like this on the outside.





The inside did not look much better. But after cleaning and proper grease, it looked like this.





Unfortunately I couldn't do anything more to restore the finish on the cogs. Corrosion had eaten that off long before it came into my hands.

dddd

With corrosion like that, how fortunate that the insides weren't rust-pitted.

Looks like a good vinegar soak took place...

Oil applied from the outside is indeed temporary, but I've never had to apply it more than once every two years or so.
Conditions here are normally dry however.

auchencrow

I use a Park Tool toothbrush and WD40 to clean FW's - though only if it's a primo item that really looks salvageable.
Even then, most are deep-sixed, because with a new chain, they end up skipping under load anyway.
(YMMV if you're not a masher).

mstateglfr 

I use simple green HD, which is actually purple, as the initial grease and crud remover. soaking all the components in that stuff for a couple hours and then scrubbing with a nylon bristle brush gets most everything off. And what isn't removed can then soak for another hour or two before coming off easily.
rinse it with water and scrub towel everything dry.

That typically gets rid of everything visible, but I have also then soaked rusted parts in Evaporust for 2-5 hours and rinsed with water.

to get between the cogs of a freewheel, after it has been cleaned with the above process I then spray some wd40 and spin the wheel while holding the edge of a towel between the cogs. the edge fits right in between and the spinning plus wd40 gets the towel edges dirty pretty fast with any remaining dirt/grime/grease.

Freewheels come out looking pretty new after this. Mostly because I am convinced I get most of my bikes from people who rode them thru dirt and mud 20-30 years ago for a few hundred miles and then left em to rot. The years have made cleaning a chore, but the components are often flawless once clean.

lostarchitect 

This works, but it destroys paint and rubber--so be very careful.

old's'cool

I can usually get things pretty clean with straight kerosene (the basis of WD40) and a toothbrush. I can buy kerosene in bulk at my local gas station, so it is quite cheap for me.
Carb cleaner, or Berryman's solvent, that you can get in auto parts stores, takes cleaning to the next level, but be sure to use as directed.
Cleaning a freewheel is much more efficient and effective if you dismantle it first, as illustrated by Bob. And scraping the heavy crud first will save time, effort, and cleaning media in the long run, as mentioned by dddd.

dddd

Not to mention the toluene fumes are horrendous.

Carb cleaner is designed specifically to dissolve gasoline varnish, but as a bike parts cleaner for really tough grime I find that Finish-Line Citrus Degreaser works even better.
This is a petro product that contains no water, and works best using a tiny amount that's allowed to sit for a couple of minutes. It's fairly smelly but nothing near as bad as carb cleaner, and very effective on sprocket grime. I wouldn't soak plastic or rubber in it for long.
A drop or two of this stuff on a toothbrush will usually do one flange of a grungy hub in a built wheel, which I follow up with a spritz of rubbing alcohol on the same brush. It's an easy way to clean at the spoke attachment crevices, gets the job done yet uses nearly no cleaning product at all.

Antieverything

I never let them build up grime. I spray it, scrub it, rinse it, every time I ride in the rain or every few rides if it's been dry. Simple green and the garden hose outside, dry in front of a fan inside, air blow water out of hidden areas, then rubbing alcohol the stubborn stuff, a pledge wipe down to shine it up, then lube the chain and all necessary items. Even the beater gets the same treatment.

willydstyle

what's the easiest way to apply cleaner to the chainring without getting it on the chain without breaking the chain?

Antieverything

What cleaners are you referring to? basically if it ain't strong enough to damage the paint it won't be strong enough to hurt the chain. Anytime you ride in the wet or get the chain wet when cleaning you should let it dry then relube. Most people clean the chain with wd40 and at the same time use a rag/toothbrush to scrub the cassette and chainrings at the same time.

Velognome 

Gunk engine cleaner ( safe for paint and plastic),\; spray it on, let is soak, wash it off. Then lube the chain and you're ready to go. If it's really grimey, an old tooth brush works wonders.

radeln

There is an air freshener called Pure Citrus that is made of orange oil. It cuts through old oil and grease very well, not too toxic, and smells nice. X-marts and places like Home Depot should have it. I haven't tested it for paint safety.

Dave Cutter

+1

Reynolds 

Just leave it alone and call it patina.