In the local hardware store I found this ultra cheap lithium soap grease. Can I use this for lubrication of my bicycle chain?
No, lithium grease or similar grease compounds are in general not suitable for bike chains.
Bike chains need lubrication of inner surfaces between rollers. Chain lubes contain solvents to reduce viscosity enough to creep into these gaps. The solvent dissipates and leaves a high viscosity oil.
The surface does not need extra lubrication. It is best to remove all chain lube from it to prevent dust and grit adhering to the chain. Eventually it would get into the chain rollers and increase wear.
Lithium complex grease is good for mounting parts. For example seat posts or screw threads. It can serve as an allround grease in place of anti seize compounds and bearing grease. There are a few components, like suspension forks, that must not be lubricated with lithium grease though.
When lubricating a chain, we need to get the slippery stuff "into" the chain.
Specifically it needs to get between the rollers and the pins, marked in RED below.
This is the area that takes all of the pressure from the chainring tooth, while rolling as the chain bends and straightens, as it does while entering and exiting the toothed rings (chainring and rear cogs and any pulleys)
To get the lubricant inside that area, it has to be carried in by a carrier fluid, which then has to evaporate or dry off, leaving the lube behind in the right place. The only way in is around the sides of the rollers.
There is also an advantage to having some lubricant in the areas marked in green, where there is a sliding friction but there is no pressure friction.
Notice the outside has absolutely no need of lubrication. Your chain should be clean and dry to the touch. The rear mech does not guide the chain by the outside so no lube needed there. The front mech does push the outside of the chain, but we change the front far less so its not a big deal there to have some dry friction for a short time.
Your grease is just that, a complex hydrocarbon concoction intended to stay inside a bearing where it is put. Grease is not intended to "move" to a new location before settling down. So a grease will not get into the rollers where its needed. However grease will actively stop the right lubes from getting in, so de-grease before re-lubing.
The three "good" lubes for a bike chain are Wet lube, Dry lube, and Hot wax. In summary:
- Wet lubes are an oil with a capillary action. They "wick" themselves along a narrow crack and will soak into the right place. Should be done on the bike. These are somewhat resistant to rain.
- Dry lubes are wet lubes that have a solvent content as a carrier. The solvent wicks into the right place, and then dries off after a few minutes. This leaves behind a dry waxxy layer of lubricant. Should be done on the bike. These are less resistant to rain
- Hot wax literally cooks the chain in liquid paraffin wax. This allows molten wax to wick into all the crevices, and then sets. The chain is then removed from the cooling wax and allowed to set. Excess wax is removed from the outside for later reuse. Must be done off the bike, in a heating appliance.