Who knows why a chain gets lube on the outside?

[Allrounder]

I am taking a guess here, but with my 4 years of science at university, I would guess there is a slight magnetic force over the whole chain and sprockets, which then "spreads" the lube over the chain equally.

 

As a bottle of oil is not magnetic, but very small amounts of liquid do have some kind of polarization.  

[Allrounder]

And before you say a chain is not magnetic or blah blah, it is possible to build up a magnetic pole due to the constant friction. 

[Fat Boab]

I am taking a guess here, but with my 4 years of science at university, I would guess there is a slight magnetic force over the whole chain and sprockets, which then "spreads" the lube over the chain equally.

 

As a bottle of oil is not magnetic, but very small amounts of liquid do have some kind of polarization.  

 

 

And before you say a chain is not magnetic or blah blah, it is possible to build up a magnetic pole due to the constant friction. 

 

It's an electro-magnetic drive! Someone call the UCI!!

[Fat Boab]

There some interesting stuff on chains and lube on Sheldon Brown.....https://sheldonbrown.com/chains.html

[carbon29er]

The only issue I have with Fat Boab theory is wax, like squirt, does not have high viscosity once applied and dry.

 

Karlito is possibly correct, friction is what keeps a chain lube free.

 

We are getting closer to a reason that is plausible.

[Fat Boab]

The only issue I have with Fat Boab theory is wax, like squirt, does not have high viscosity once applied and dry.

 

Karlito is possibly correct, friction is what keeps a chain lube free.

 

We are getting closer to a reason that is plausible.

 

Don't know enough about this wax stuff. Does it deform? Does it melt? Is it visco-elastic ie a non-Newtonian fluid?

[Eugene Brown]

So a theory.... if we believe that lube is applied inside and works it way outside, and eliminated the sprocket, chainwheel RD/FD route, then it has to flow through a narrow path consisting of roller, pin, and holes in the inner/outer plates. (See diag). And as the lube would have a high viscosity, then capillary action would be significant, so it would be drawn through the path. Add to that the clearance in that route changes as the chain rotates through sprockets etc, it would flush the path, and capillary action would stop the lube being drawn back inwardly so it would migrate outwards.

 

chain.jpg

Good thinking!

[SwissVan]

Something I've been pondering recently on long, slow rides:

 

Why does lube paste itself on the outside plates of a chain when it is applied between the links?

The lube jumps to the outside of the plates because it does not want get mashed and mushed between the rollers and teeth on the cassette and chain ring.

 

Think about it, if you were applied into a chain, what would you do if you saw those teeth coming around every few seconds?

 

Sometimes if the oil is lucky it escapes onto the frame or humans body parts

[LongDonkey]

A mix of all your theories. The lube is a non Newtonian fluid, not sure if it can be defined also defined as a Bingham plastic fluid in certain types of lube, but highly probable. The viscosity will vary depending on the type of lubricant used. The rotation of the chain link and bushing (thanks for the photo Boab)and its various components will force some of the fluid out of the contact surface. Dust etc will always be present and will deposit on the location with the least interface with other mechanical parts of the system, i.e. chain links, rollers, chain rings, cogs, fingers etc. Capillary action on a dust particle scale will then permit the migration of the fluid to the area or least disturbance on a continuous basis. Even if there is limited dust, the "greasy" lubricant will still be displaced by mechanical pressures on the various contact components and still migrate to a location with no moving parts. 

 

Anyone wanna borrow a text book on this? Its very cool stuff even if my wife thinks its boring.

[SwissVan]

Well there is pressure and friction between the rollers and the teeth of your ring & cogs which will eventually "clean" the inside of the chain and push the lube out.

 

The outside has little contact with other surfaces so it stays dirty.

This is what I meant, I just tried to keep it simple and easy to understand.

 

Another theory I have is that it's a plot by the oil companies to ensure continued demand for their products

[porqui]

The lube referred to in this fred is obviously OIL and not dry lube as this would not happen to DRY lube.

 

Who still uses oil lube ??   (rhetorical)

[stefmeister]

So a theory.... if we believe that lube is applied inside and works it way outside, and eliminated the sprocket, chainwheel RD/FD route, then it has to flow through a narrow path consisting of roller, pin, and holes in the inner/outer plates. (See diag). And as the lube would have a high viscosity, then capillary action would be significant, so it would be drawn through the path. Add to that the clearance in that route changes as the chain rotates through sprockets etc, it would flush the path, and capillary action would stop the lube being drawn back inwardly so it would migrate outwards.

 

chain.jpg

Hypothesis.

[porqui]

Hypothesis.

 

Tomorrow !!

[LongDonkey]

The lube referred to in this fred is obviously OIL and not dry lube as this would not happen to DRY lube.

 

Who still uses oil lube ??   (rhetorical)

Well if the chain is "dried" as previous noted, then the amount of lube will be reduced that needs to be displaced between the chain roller and bush. But basically there will always be a certain amount of lube retained in the inner portions of the chain that can not be wiped off. until the bike is used. Using "dry" lube would theoretically have the same behavior, but to a much lesser degree. Probably something that would not be visible. The dry waxy material would tend to flake off instead of build up. Unless its is super hot like in CT these days..... But yes, what you said.

 

PS, this is the only thing i know a little about when it comes to bikes.

[Fat Boab]

Hypothesis.

 

Correct! For you....a gold star! 

[stefmeister]

The only way to get an answer is to perform a set of experiments to determine the pattern [and cause - but that can easily be ascribed to forces (radial acceleration) acting on an object/material etc] of migration of lubricants on a chain.

Start with a clean drive train. Apply lube to rollers/bushings. Remove excess lube. Record (i.e. photograph) the chain at predetermined intervals. Observe results. Repeat the whole process. Test against a control sample (i.e. clean drive train with no lube). Compare and test results. Formulate a conclusion. Sleep tight.

 

What you might learn is that the lube will eventually migrate from the bushings/rollers to the rest of the chain. At 90 rpm cadence and a 32T chainrings, your 114 link chain make ~25 revolutions per min or 1.5k time per hr. Suppose that's enough movement to get a bit of wax displaced.