Wobbly cassette

[Ajax Bay]

Lithium grease is the correct material for bearings. Most "standard grease" is lithium grease . Grease is a mixture, I'm not sure whether it's chemically an emulsion or a suspension, of a soap and a lubricating oil. The lithium bit is the salt used to form the soap component. The soap stops the oil draining away, if it's a water soluble soap, like the sodium soap in your bathroom, the grease is water miscible. If it's not water soluble, like lithium soap in lithium grease, it's waterproof.

Sparked by the 'waterproof' word, I hope you don't mind if I recycle a couple of old posts on grease from the dormant @Yellow Saddle - because I had recalled this ground had been covered before (unsurprisingly).
"Bicycle lubrication is simple and primitive. There is no component that requires anything special other than ordinary grease or oil. So, whatever grease you have in the garage, that's the right one for your bike. It could be Lithium, Calcium or any such automotive grease. Note that there is no such thing as waterproof grease, even if the tin says so. Grease is NOT a waterproofing agent since it readily emulsifies with a bit of water and massaging, as you would find in a turning bearing or a wiggling seat post. Marine greases use Calcium soap (the technical term for the salt used as the grease's base) which doesn't break down as easily in salt water. This simply means it doesn't change chemically when in contact with salt water. It does not mean that it still protects from corrosion when it emulsifies. It merely retains its lubrication properties better.
"Just remember that no matter what Halfords wrote on the can, Copper Compound is not grease." (And nor is carbon paste.)
@Dogtrousers shared his discovery:
Grease is a semi solid lubricant. Grease generally consists of a soap emulsified with mineral or vegetable oil. The characteristic feature of greases is that they possess a high initial viscosity, which upon the application of shear, drops to give the effect of an oil-lubricated bearing of approximately the same viscosity as the base oil used in the grease. This change in viscosity is called shear thinning. Grease is sometimes used to describe lubricating materials that are simply soft solids or high viscosity liquids, but these materials do not exhibit the shear-thinning properties characteristic of the classical grease. For example, petroleum jellies such as Vaseline are not generally classified as greases.
Also:
https://www.cyclechat.net/threads/how-do-you-remove-these-rear-bearings.245842/#post-5540866
@figbat is the forum tribologist.

 

[MontyVeda]

A couple of weeks ago I noticed my cassette was wobbly. On closer inspection, the cassette wasn't just wobbly, it'd completely fallen apart!

Somehow, the lock ring had removed itself and was hanging on the axle, allowing the cassette to shift sideways and thus, sheered the pins. I can't work out how the lock ring unscrewed itself... surely the physics of pedalling would cause it to tighten rather than loosen?

 

[Ajax Bay]

No: pedalling has no tightening effect on a cassette lockring. Tighten it to 40Nm (tight - 6 clicks, I find).

 

[figbat]

@figbat is the forum tribologist.

Sadly not quite true. I am a lubricant technologist (formally an “expert technologist” if my job title is to be believed!) and do dabble in tribology (as well as rheology, chemistry, engineering and a whole melange of sciences) but I am not a qualified tribologist; I do work with people who are though. I’d call myself a well-read generalist.

Greases are not an area I have spent much time with and the post above says pretty much as much as I could.

 

[Gillstay]

Marine greases use Calcium soap (the technical term for the salt used as the grease's base) which doesn't break down as easily in salt water. This simply means it doesn't change chemically when in contact with salt water. It does not mean that it still protects from corrosion when it emulsifies. It merely retains its lubrication properties better.

https://www.cyclechat.net/threads/how-do-you-remove-these-rear-bearings.245842/#post-5540866
@figbat is the forum tribologist.

Brilliant, I bought some marine grease in the 80's in Spain and always used it on the motorbikes that went through winter and it was better in the salty condition, but I never knew why. Every day is a school day , Yeah.