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February 26, 2017 3 Comments
One of the most memorable characters in our cycling scene of the early 1970’s was Phil Wood who, with his wife Vada and manager Bern Smith, pioneered the modern use of cartridge bearings in bike components. Here Bern recalls some of the special challenges:
Here's an introduction to the complexities of specifying, testing, purchasing, re-testing, lubricating and assembling bearings. Some of this will be pretty pedestrian to folks with working knowledge of bearings, but there's plenty other facets to it.
In the earliest days of Phil Wood & Co. circa 1972, once Spence Wolfe had convinced Phil to manufacture some maintenance-free hubs, and they agreed that 50 pairs would be the most they could ever sell, Phil started testing bearing and lubricant samples. He settled fairly quickly on a single domestic manufacturer of bearings, but the grease samples were...disappointing...
He found 'waterproof' grease that dissolved in water, grease that absorbed water, swelled up and forced itself out of the bearings past the seals, and other oddities. Eventually he found a product from a local (Bay Area) supplier that was something of an oddity itself - the manufacturer produced only very small batches of this particular grease, and only occasionally. It was somewhat inconsistent in texture and color. But after Phil consulted with them a little, they changed the mix, and after that it worked really well in full immersion salt bath tests.
And it was green...
So we were off and rolling...
We specified that grease to the bearing manufacturer for lubing at their factory. Then the fun began.
A tangent (and a quiz) are required here.
• What is the highest rpm a bicycle bearing is ever likely to spin?
• How many rpm's is a regular radial-contact industrial ball bearing typically tested to maintain without burning out?
• How hot do you think bearings get at max rpm?
• What causes that heat?
• What exacerbates it?
...and what is the maximum percentage fill of grease in the bearing assembly cavities (those gaps between the bearings, their retainers, and the seals) that most any manufacturer will agree to?
Back to the early bearings. We found soon enough that our idea of how much grease a bearing should have in it was vastly different from what the bearing suppliers were willing to provide. Typical over-the-counter industrial bearings are filled ~25% full with grease. That's because those bearings, in a normal installation (an electric motor, say) might run as high as 10,000 rpm - 10 times higher than a bicycle bearing will ever spin. A bearing running at 10,000 rpm gets hot - really hot - from friction, and hotter still if it has too much grease in it (retaining heat in the assembly). Too much grease meaning anything over about 25%.
We specified 95% fill because our tests showed that provided satisfactory water resistance in the extreme tests we put bearings through. But the suppliers refused, citing product liability, and other not-pertinent reasons. So we had to lift seals and add grease to each bearing. That probly doubled our bearing cost.
At least we were getting good bearings...until...batches started arriving from the factory with large grit, wood chips, crystals and other unknown stuff. We rejected lots of bearings. It got so bad that, in the final batch we rejected from the original supplier, most of the bearings would not rotate. Now, there's a handful of things a bearing needs to do, but above all...
Eventually we found a (foreign) company that produced consistently good bearings for considerably lower cost than the others. Were they eventually prosecuted for dumping bearings in the U.S. to put domestic factories under? Another story for another time...
Then the grease started to get weird...
As you might have guessed, as we grew more comfortable with the grease we chose, we had an idea that maybe we could use that grease for other purposes, and maybe other folks might like it as well. In particular, we felt that the lovely deep green color itself could help sell the stuff, and we settled on a slogan - 'It's Green!'. Anyway, we asked the manufacturer about making larger batches, that we could repackage from 55 gallon drums into 3oz tubes. They asked how much we might ever sell...
Each time we got ready to order grease for repackaging, I went to the lab at the lubricant plant and inspected samples. They had a few minor problems and we rejected some batches - turns out that the grease mixing vat was used for several different products and occasionally did not get cleaned out completely between product switchovers. Eventually the plant assigned a mixer for this grease alone, and things smoothed out.
At one point, after about 3 years without a single problem, I asked Phil if maybe we didn't need to go to the plant to check the samples first. We looked at each other for a moment and said simultaneously "Check the grease"...So I drove to the plant and met the project manager in the lab, where he pulled out the latest sample. It was a beautiful, deep black. Lesson learned the easy way for once.
Years later, after the project manager had retired, I related that story to his successor, who laughed, and said "Oh, yeah - he was colorblind!"
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