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Comment by bshimmin | Hacker News Reader

I suspect many people who've ever idly looked at a zip will have noticed the letters "YKK" on them, and at least a few of those people will have made it to YKK's Wikipedia page, which is at least equally as informative as this article.

I was a bit confounded by this sentence: "The precision necessary to craft a working bicycle chain or a smoothly meshing zipper was simply beyond us for all those prior millennia." Surely the author means to write "The precision necessary to craft ... on a massive scale"; of course we've been able to build things requiring comparable or greater precision for centuries, but to build the machines necessary to mass-produce them is a relatively recent innovation. Or perhaps he was just joking.

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Roller bearings are old, but no one ever made a ball bearing until the bicycle era. They grew up together, and the first ball bearing equipped bicycles dominated competition about a century ago. Ball bearings were the carbon fiber of their era.

I don't think ball mfgr technology of a level of roundness and surface quality suitable for ball bearings was compatible with ancient technology. The metalurgy would be highly questionable but that aspect would be possible.

You are partially correct that roller chain could have been built by ancient craftsmen if they had the idea, but the invention credit is about a century ago. The metalurgy would have been questionable, the ancients would have ended up with chain links the size of your fist, which would have screwed up weight and power transmission making a v-belt a lot more likely. I'm surprised bicycles don't try v-belts.

Here you go:

http://en.wikipedia.org/wiki/Belt-driven_bicycle

Well, those look like kilodollar+ custom jobs. I guess I was thinking more stereotypical department store bike from China, where the mechanics aren't generally much of a priority so introducing something isn't very dangerous.

You can either shove innovation in at the top where R+D fits in the budget, or at the bottom where reliability is never assumed anyway.

    I'm surprised bicycles don't try v-belts.

With a standard frame the chain goes through the rear triangle. To install and replace the chain you need to be able to open it at a master link to get it around that piece of the frame. Both the v-belt and frame do best if you don't open them.

I think that this is only part of the story. It isn't only that we didn't possess the technology to mass-produce these things, we also lacked the need to produce these things at all, let alone in mass-quantities.

The need for a chain that is used to transfer energy between two gears, like a bicycle chain, would only be apparent to you if you had a regular source of energy, like say an electric motor or internal combustion engine. After realizing that these things could be used to turn motors at unprecedented speeds, you would naturally look for ways to more efficiently transfer energy between the motor and a receiving point to harness the energy for something useful. Then you would design a system of gears and chains.

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