General Treatise on Chain Lube Theory
A while back, a friend passed a usenet post on chain lubes to me. Wish I still
had a copy, but to paraphrase and expand on it (and if you wrote it,
drop me a line, please):
What does any good lube do for a moving, sliding, rolling mechanical part? It:
- forms a film to allow the bearing surfaces to float past without touching.
- carries along some plastic junk to fill in any cracks that may have formed.
- in a last-ditch effort when pressed beyond all reasonable limits,
polymerizes to form yet more plastic junk to coat the bearing surfaces.
Additionally, lubes are frequently used for their incidental anti-corosion, cooling,
debris-flushing, and (maybe) dirt-shedding properties. Cooling's usually not
important on a chain, so I'll ignore it here. Likewise, cleaning properties are
only important when you're doing maintainence, so I'll overlook them too.
On the subject of maintainence, one more property desirable in a chain lube is
durability, or measure of how long it can work between re-applications.
This is not so much a measure of how long a given drop lasts in a given spot
but rather a measure of self-replinishment via wicking from other areas of the
chain.
Bike lubes come in 3 general forms: dry, semi-dry, and wet. Listing all this is
about to get cumbersome, so let's tabulate what does what (+ = good at, ~ =
has some of this property but isn't a champ, and - = neglegable or none at all):
|
| film
| fillers
| poly-ability
| anti-cor
| shedding
| durability
|
| dry
| -
| +
| -
| -
| +
| -
|
| semi-dry
| ~
| ~
| -
| ~
| ~
| -
|
| wet
| +
| *
| +
| +
| -
| + (usually)
|
* - easily added
Cut to the chase: with one exception, wet lubes rule. That exception?
Deep sand. It will stick to a wet lube, get sucked into the bearing surfaces
on your chain, and (possibly worst of all) turn this stuff's wicking properties
against it and suck your drivetrain dry. Use the dryest lube you can find if
you've got to ride in bad sand.
Enough! I didn't expect a steenkin' lecture!