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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!

3
  • You need a toothbrush. May 21 at 21:35
  • They are called sprockets.
    – mkrieger1
    May 22 at 19:42
  • @DanielRHicks Put 'em in the dishwasher. Just don't tell your wife. ;-) May 23 at 11:56

5 Answers 5

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This answer concerns solely the situation when the cluster is removed from the rim e.g. changing a spoke or a hub.

It splits into a couple of individual spockets plus a riveted buch of them.

Clean the individual ones with a rag. Its simple, quick and easy.

The riveted ones :

  • Clean with the rag.
  • Then go to a place where you don't care about ugly oil stains or toxic oil ingress into soil.
  • Wear a glove on the hand holding the cluster.
  • Clean the major inter-spocket gunk with a piece of wire e.g. an old spoke.
  • Spray the cluster with pressurized brake cleaner or any other degreaser.
  • Spray with pressurized water.
  • Let it dry(don't fear rust).
  • Do NOT apply any lubricant to the clean cogs.
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  • It is possible to drill out the rivets and simply work with a stack of separate cogs and spacers, but in my experience the rivetted sprockets tend to be the 2~5 biggest cogs, so there's plenty of space for dirt to fall through between, unlike the 11~16 tooth cogs that have a closed bottom to their valleys when assembled.
    – Criggie
    May 22 at 13:08
  • @Criggie drilling the rivets and reassembling sounds like an insane amount of work for a task which we are not sure is worth at all. And to digress and use the comment for another topic. I noticed I have bent a tooth. And the 3rd one. And the 5th one. And 7th one and so on. 2021 GRX cassettes have something going on!
    – Vorac
    May 22 at 13:44
  • @Vorac the odd/uneven tooth shape is to make shifting work better. May 22 at 22:41
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  • clean it outside, or somewhere that falling oily dirt isn't a problem. Spread newspaper as a drop cloth if you have to.
  • get the wheel out of the bike. Makes it easier.
  • use a pick or smallish screwdriver or a knife to scratch large clumps of oily dirt out of between cogs. Perhaps do this over a rubbish bin.
  • spray on some solvent or cleaner.
  • use some soft rope or cord as glorified dental floss and pull it between each pair of cogs. There's literally a product called gear floss for this but any scrap twine will do. Dispose when it gets too dirty.
  • Wipe the cog teeth with a cloth. You can generally only do the right-hand side.

Then put the wheel aside, and duplicate most of that on your jockey wheels. They hold an excessive amount of dirt for their size.

The chainrings are generally pretty okay - perhaps being further forward helps.


I've personally had so much road dirt between the two smaller cogs that the chain would not sit well and skipped forward under high power. It wasn't also obvious from a standing position because of the black cassette, that's my excuse !

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  • 3
    Woah! I've always used the edge of the rag as a "dental floss" and always been frustrated at how difficult it is. Never thought of using something rope-like. From now on my days will be brighter! ... But one should do the spoke poking before that.
    – Vorac
    May 22 at 13:54
  • 1
    The rope is a really cool tip! So far, i have used plastic cable binders to scrape off the bigger chunks.
    – Burki
    May 23 at 8:12
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Voracs answer is great but if you’re reluctant to remove the cluster for whatever reason or just want to do a sub 5 minute job you can use a brush to remove the majority of the goo. This won’t be perfect but is good enough.

  • Remove back wheel.
  • Clean between sprockets with spoke/wire/knife/etc. That gunk is good at staining carpets, so make sure you sweep up well after.
  • Use a citrus cleaner (citrus won’t effect disk rotors) and pour a small amount onto brush or dip into a small dish of cleaner. If your cleaner came in a spray bottle, spraying is fine too.
  • Scrub the cluster with both radial and circular motions. Repeat a couple of times. Get the bristles between the sprockets for best results.
  • Hose down with low pressure water.
  • Return wheel to bike.
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  • 1
    mechanica removal of the caked grease is the most important step. I also found a stick the most useful. A brush quickly takes up all the dirt and just smears it every where. With a stick you can get under it and flick it out.
    – gschenk
    May 23 at 13:02
  • 1
    There are some bike brushes - example with both a selection of stiff bristles on various angles and one or two plastic hooks/teeth that do a good job of getting muck out of cassettes and jockey wheels. They're design to fit between the cogs.
    – Chris H
    May 23 at 13:14
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Use a suitable cleaning fluid. Solvents like petrol/gasoline/diesel/kerosene work but can be hazardous.

Plain water does not get the job done, while soapy water is good for dirt it does little for oils. Use a fluid intended for chain cleaning .

For example, I swear by Morgan Blue chain cleaner. I have used a number of citrus-based products, the Park Tool product, and Simple Green. All of these work to clean a chain but Morgan Blue tops them in my opinion for effectiveness. I have seen it available on eBay and a few internet shops.

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  • gasoline is my favorite. the greese just comes off
    – Riza Khan
    May 24 at 23:40
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For really stubborn grease-based muck, I keep a bottle of white spirit (mineral spirits) on the go. A good soak plus shaking/brushing and that will loosen the worse caked on grease (use a suitable tub to hold your parts). I then filter the solvent back into a clearly labelled bottle, using paper towel in a funnel, so you don't even consume much. Of course this also requires removal of the cassette.

Short of an ultrasonic bath it's the only way I've found to deal with oily mud inside a freehub. An ultrasonic bath would have to be pretty big to to take a container that will hold a cassette (in general you use clean water in the bath itself, solvents etc. in an inner vessel)

Finish with whatever bike-cleaning detergent you have anyway.

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  • I have an ultrasonic bath cleaner - 800 mL is far far too small for a cassette. Also it clogs up the liquid fast if your item is dirty, so I end up cleaning the worst off by hand before putting it in the cleaner... which is akin to washing your dishes by hand before filling a dishwasher. A 2L would be the minimum, and 4-5L would be much better. 0.8L is only good for screws and similar.
    – Criggie
    May 23 at 11:01
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    @Criggie if I get one, it will take a cassette in an inner container. I have used a small (1l I think) one in work for a freehub, and the bath is only mean tot be filled with water; any solvents go in a lab beaker or jam jar inside
    – Chris H
    May 23 at 11:52
  • 1
    Is a plastic bag good enough as inner container? Does the fluid in a (thick walled) jam jar couple well enough to the fluid in the basin of the ultrasonic bath?
    – gschenk
    May 23 at 12:59
  • 2
    @gschenk A sturdy bag might be. Coupling through a lab beaker is efficient, and a jam jar should be stiffer (therefore better). Certainly my experience was that it worked well
    – Chris H
    May 23 at 13:05

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