Grease is the word

[Johan Bornman]

I often get PMs asking about lubrication and more often than not, get involved in some sort of oil fight. I've given my view on oil more than once. I've decided to pre-empt most questions about bearing grease with this piece. As soon as I figure out how my website works, I'll post it there as well. We really do need a FAQ section on The Hub. Admin, are you listening?

 

Grease.

 

Grease is an emotional subject with bicycle mechanics and DIYers, second only to chain oil. Endless claims are made about the merits of this or that grease. It appears that the more expensive the grease, the higher its praises are sung. Let?s look at the basics of grease. <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Grease is just soap and oil. The soap provides a solid matrix for keeping the oil in place. Most general purposes greases are lithium-based. Lithium, if you can still remember your high-school chemistry, is number three on the periodic table, yet is a metal. It is so light that it floats on water. This amazing metal has a low melting point and when placed on water, immediately reacts with the water, melts and cruises around on top until it has completely disappeared into the water, leaving the water soapy to the touch. The white lithium  oxide is the soap in lithium greases ? soap being nothing other than an hydroxide of an alkali metal such as sodium, calcium or our lithium and an organic substance.

Although the alkali metals are highly reactive and so are their hydroxides, by combining them with organic substances they become very stable, with the reactive alkali metal strongly bonded to the rest of the molecule. The lithium in lithium grease is actually LIOH.

The active ingredient in grease is oil, thick or thin, chosen for the specific application. The soap is merely a carrier and dispenser of the lubricant and it is selected for its melting point and viscosity. Obviously, a lower melting point is not suitable for hot applications. The viscosity is an indication of how quickly the grease flows away from its original location. Lithium greases have a relatively high melting point but since cycling doesn?t produce any particularly hot bearings, this is largely irrelevant to us. Grease fails by going a.w.o.l. from where it is needed ? a sign of too low viscosity. 

Grease lubricates a friction interface by slowly seeping small amounts of oil onto the interface. We can say the soap ?dispenses? the oil but has no lubricating function of its own. The soap is completely inert but the oil not. Very old grease can separate and here you often see blobs of soap and oil in the container. Just about any type of oil can be used in grease, including the stuff nature gave us, synthetic oil or any of the other lubricants made of silicone or molybdenum.

The fact that the soap is inert is misunderstood by companies like Rock Shox. They post dire warnings about the use of lithium grease in their forms, claiming that the lithium will somehow degrade the seals. This is nonsense, petroleum products degrade some polymers but not lithium. For some reason they don?t warn about petroleum products though. Any lithium grease is perfectly safe to use in MTB forks and won?t harm the seals. I suspect it has to do with sales of overpriced <?: prefix = st2 ns = "urn:schemas-microsoft-com:office:smarttags" /><?: prefix = st1 ns = "urn:schemas:contacts" />Judy ButteronName>.

Grease can have other alkali metals as its base and you may occasionally come across calcium or Sodium grease. Lithium grease is the common type and imminently suitable to cycling.

O-Ring and wiper seal companies understand the compatibility between their seals and many different many fluids and publish this data openly. There is nothing in a fork that is not compatible with standard seals, O-rings and rubber bumpers found in forks. 

Boutique grease companies will tell you that the difference in their grease lies in the secret herbs and spices ? a.k.a. additives. Most grease manufacturers add one or other anti-oxidant to their grease in inhibit oxidation (rust) of the wear parts. Grease designed for marine use has more than that for motor cars. This doesn?t mean the grease is waterproof.

Grease readily emulsifies and traps water by encapsulating the smaller water molecule inside large grease molecules, keeping it at the ready to attack unprotected metal parts. Grease shouldn?t come in contact with water, especially grease that is agitated, such as that in a moving bearing. It simply absorbs the water. The same goes for greasing dynamic joints such as quill stems, pedals and saddles. The movement pumps water into the interface and mixes it with grease. Once emulsified, it won?t evaporate and remain inside the grease, doing much harm.

Copper grease, used to prevent seize-up of mating metal parts and fusion of dissimilar metals, is not grease. It has no lubricant and was not designed for reducing friction, but for preventing fusion. It emulsifies less readily, but should still be watched and regularly changed when used in quill stems. These are best left ungreased.

Lithium grease is cheap and best purchased by the 500g can. One tin will last the average DIYer a lifetime. It works on your car, lawnmower and door hinges as well. I dispense it from a cheap plastic syringe. Cyclists apparently have plenty of used syringes lying around, so should have no excuse for a mess.

Not only is lithium grease cheap, it is also white, which helps you identify contaminants. A bit of water ingression will quickly oxidize the steel inside and turn the grease brown. Replace immediately if you see this. It indicates a mixture of emulsion and rust ? both are bearing destroyers.

The only place where lithium grease is not suitable for use on a bicycle, is in obsolete Shimano Octalink BBs with needle rollers. Grease doesn?t replenish itself very well in needle rollers. In a ball bearing, it churns and returns to the interface from where it was pressed out. In needle bearings it follows a one-way street ? out. The same doesn?t hold true for Stronglight needle roller headsets, since the needles don?t rotate but only rock. This has problems of its own, but nothing to do with the type of lubricant used.

Whenever a bicycle was submerged in water, the grease needs to be replaced and bearings repacked. High-pressure washers are the enemy of bicycle bearings as is a rainstorm when the bike is on a roof rack on a fast-traveling car.

Grease is the word, is the word, is the word.

 

 

 

 

 

 

 

 

 

[Windbreaker]

 

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Grease is the word' date=' is the word, is the word[/quote']

Sorry to say Johan but you will have lost the vast majority of hubbers on that one... They'll be complaining about your lack of humour again.

 

 

 

 

[mbaymike]

huh

[Windbreaker]

 

huh

See!!!!!!!!!!

[Johan Bornman]

...

 

 

 

 

Grease is the word' date=' is the word, is the word[/quote']

Sorry to say Johan but you will have lost the vast majority of hubbers on that one... They'll be complaining about your lack of humour again.

 

They just dont have groove, don't have motion....

[mbaymike]

johan some hubbers must have been hounding you like mad for you to have written this

[dirtrider]

haha you people are a bunch of drips ! Thanks for that bit of information Johan . Grease is in my opinion just another dirt collector and the use thereof should be kept to an absolute minimum . There are no real moving part on a bike to justify the use of vast amounts of grease .

[Skye]

 

Ok Ok Johan can you sign us the song..... I can just remember a couple of words....to the song Grease Lighting!!!!!

 

I was in std 5 when the movie hit the DRIVE-INN, went and watch the flick about 5 or 6 times Those were the day

 

Skye2008-06-09 12:09:47

[mbaymike]

i agree with you....won't use grease if i can help it.  

[cling]

Excellent bedtime reading. Thanks JB!