The Golden Wrench

A blog about bicycle repair and maintenance by the mechanics at Freewheel Bike.

Wednesday, March 9, 2011

How Grease Works! (as far as we know)

The guy who cuts Clark Kent's hair probably doesn't have a clue, even if he happens to look down the collar and see the red and blue skinsuit. "Long johns," says the barber, dismissively, then goes back to snippin' and stylin'.

I would never have known that one of our Supercustomers makes tiny little gyroscopes that guide aerospace equipment. You know, like space ships and time machines and fancy electro-transistor huckaloogies that cost lots and lots of money and are not terribly useful for gardening. Meet Andrew Paule, the Physicist.

Not surprisingly (if you know aerospace guys), he's riding around on a set of Campagnolo hubs from 1968, and they're flawlessly smooth. He also has "Dr. Feelgood" as the ringtone on his phone, so we're absolutely sure he's a real human being.

Andrew was impressed with our commitment to the Midtown Greenway and wanted to return a favor, so he agreed to do an entire presentation on lubrication and how it works. So we met after hours on a Saturday evening and talked about grease and bearings and oils and failure and success and why old Campagnolo hubs are so awesome, and why MOPAR-based vehicles should be avoided.

Excuse me, Andrew? How does pizza grease do in the ASTM D2266 test?

It's all theory, of course, and we all know how to be responsible with theories!

Admittedly, for starters, I'm kind of a nerd. Admittedly (and admittedly, it's easier to admit the foibles of others), Freewheel has a few nerds as mechanics, as well as a few guys who don't think they're nerds but may want to check on that. Either way, some of us really enjoyed this presentation. Let's just say that Andrew was pulling the microscopic curtain away and revealing what happens at the nano-level in the highest-stress areas on your bicycle.

It's spooky.

The races on this spindle look perfect, but under a microscope...
Once we were able to wrap our minds around what he was saying, what Andrew shared confirmed many of our sneaking suspicions: many of the products we use on our bikes amount to marketing flummery and snake oil. Here was a chance to take the mythology out of lubrication and let science clarify the matter!


It turns out that science is a capricious servant: the truth of the matter was stranger than the mythology.

Grease is essentially just an oil with a thickener and some other additives to help it stay in place and smell awful, and Andrew explained that this puts it into the category of non-Newtonian fluids (think corn starch and water, then think about this before you cough up the money for this). Thus, grease exhibits different characteristics under different stresses. Under the extreme, localized pressure of a ball bearing against a race, awful things happen at a microscopic level, and that's why you get hub cones that look like this:

For the love of Grandma!

Yes, even a greased hub can do this, kittens! It turns out that grease, under the tiny contact point of a ball bearing against a race, can be harder than the metal in the tiny little universe inside your hub! So actually, the thing that is usually deforming is the bearing itself: the grease is just there to make sure that while the bearing deforms it can't weld itself to the race. Apparently it gets really hot when all the microscopic peaks and valleys in your mirror-smooth bearings and races articulate against one another.

It all seems so wrong!

That's why we put dust shields on our hubs: so that the little universe where everything is wrong can't come out and confuse us all. But Andrew the Physicist tells us there's hope.

Some greases, it turns out, resist the above effect better than others. The best ones cost hundreds of dollars an ounce and are used to make satellites go "beep beep beep" across the night sky and drop your cell phone call. Stupid robots.

This stuff costs well over $1000 per liter.
It is impossible to take a non-blurry picture of it.
It is safe to drink.
You first!
Most of the greases used in the bike industry are pretty mediocre according to Andrew the Physicist, but due to the relatively low speeds, this isn't nearly as big a deal as it would be, say, on a dragster. The greases we use all do a great job of inhibiting corrosion and slowing down the galling process, but most are not the greatest on the ASTM D2266 test. Does that mean they suck? No, they're totally adequate for bicycle applications, and may even excel in some specific uses. They just don't meet the absolute highest standards reserved for stuff like dentist drills, watches, interocitors, flux capacitors, and Twiki.

I was delighted to hear that we had some real standouts on our shelves however, and I will definitely prioritize those greases from now on when I do overhauls and bearing repacks.

Trivia Question: what is the official title for a scientist who studies friction?

First to respond correctly as a comment to this post will win a tube of each of our two highest-scoring greases according to Andrew the Physicist!

The top-scoring greases on our shelves: the venerable Finish Line Teflon, and the relatively new and mysterious Morningstar Freehub Soup!

They can be yours, if you're smart, resourceful, or lucky, or some combination thereof!

*Be sure and leave your e-mail address so we can get your prize to you!*

Edit: Thank you for all of the responses. Because your e-mails are included I will not publish them. The winner is Montesano! You can stop by our Westbank location anytime to pick up your prize.