Friday, January 27, 2006

Chain lube

This was a response to an e-mail, and I've posted it here as a basic explanation of chain lubricants and how to use them. Now, I know some of you have esoteric lubricants consisting of things like rancid yak fat rendered over a slow-burning fire of horse dung, or something 'borrowed' from a space shuttle launch. But this is intended for general background information.....Ed

I think James wrote something about chain lubrication earlier this week, and said he was using WD40 as a chain lube. I meant to reply at the time, but things intervened as things do, and I forgot about it.

WD40 is not a good choice for a chain lubricant. It's not designed to stand up to the pressure generated in a chain. However, it's an excellent choice as a chain cleaner, maybe not as environmentally friendly as one of the 'green' cleaners, but still better than kerosene or carburetor cleaner.

Simply rotate the pedals backward, and from the front of the bike, direct the spray into the chain as it goes around the chainring. Wipe off the excess and let it sit for a few minutes so the propellants can evaporate.

It's a good idea to wear safety glasses while spraying these chemicals.

There are two major types of chain lubricants: wet and dry. Wet lubricants like plain motor oil or Triflow tend to attract dirt and they'll permanently stain your clothing. Besides, chainring tattoos are the mark of a tyro. I used Triflow for years because it really does work well. Dry lubricants, on the other hand, are mostly wax. They have to be replenished more often than wet lubes, but they don't attract dirt, and for the most part, they don't leave stains. (More on that in a moment.) The boutique lubes are mostly clear waxes, but I've started using Amzoil's Metal Protectant Heavy Duty (MPHD), a brownish wax that costs far less than boutique lubes. It has the disadvantage of building up on chainrings and cogs, leaving a ridge of hard to remove brown wax. It's a very good idea to wipe down as much of the chainring as you can after applying this stuff. And because it's a brown color, it will stain clothing, but not to the extent of wet lubricants. MPHD is also suitable as an undercoating, and I've used it inside my steel frames to prevent corrosion.

One other thing about Triflow - it was originally developed as a lubricant for military arms, and will stand up to immersion and even salt water far better than any oil. I've used it to lift difficult-to-remove black powder fouling. It will withstand heat and pressure, so it's an excellent choice for a firearm.

Why is chain lubrication important?

The chain is the cheapest part of the drive train. As it wears, it causes wear on the chainrings and cogs also. Dirt is a fine abrasive that accelerates the process. So if you want to avoid replacing the expensive bits, keep the chain clean and lubed, and replace it before it reaches it wear limit.

The wear limit (or chain stretch as it's sometimes called) is 1/8 inch over 12 links.. You can measure that easily with an ordinary ruler. A brand-new chain will measure precisely 12 inches over 12 links. One that's ready to be tossed will measure 12 1/8 inches. Just measure between pin centers.

It's not always necessary to replace a cog along with the chain, but if you experience crunching noises and pops after replacing the chain, it may be time for a new cog too.

A clean, well-lubricated chain runs quieter and shifts better than a dirty one. Sometimes you can even feel the difference when pedaling. A clean chain runs smoother, where a dirty one causes noticeable vibration in the pedals.


Blogger yumanbing said...

Good, informative post. I use the wax lube myself and I find it much friendlier than oil on all accounts.

By the way, I'm well aware of how dirt clings to an oily chain, but I'd love someone to explain the physics of how oil somehow "attracts" dirt.

7:21 PM  

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