141–150 of 515 posts
As a side-side note, ever asked someone (friends, family, etc.) to draw a bycicle by heart? This guy did: http://www.gianlucagimini.it/prototypes/velocipedia.html
This is cool. Except it's driving me nuts that I can't figure out what's wrong with the first picture, or at least why it would immediately break.
As a side-side note, ever asked someone (friends, family, etc.) to draw a bycicle by heart? This guy did: http://www.gianlucagimini.it/prototypes/velocipedia.html
This is cool. Except it's driving me nuts that I can't figure out what's wrong with the first picture, or at least why it would immediately break.
It's an exaggeration to say it would immediately break. But if you put weight on it, it will tend to spread out (imagine putting weight on a bent piece of metal shaped like a ^). Still, the front fork isn't braced, and bikes exist with quite a large rake angle on the front fork (think a Harley-Davidson style chopper). So maybe you can make this design strong enough to bear a person's weight.
As a side-side note, ever asked someone (friends, family, etc.) to draw a bycicle by heart? This guy did: http://www.gianlucagimini.it/prototypes/velocipedia.html
This is cool. Except it's driving me nuts that I can't figure out what's wrong with the first picture, or at least why it would immediately break.
Why did we wait so long for the elevator? Circular dependency and incentive. Combining a ratchet with a pulley is incredibly simple and both have been around since the ancient Greeks. But with a few exceptions, it didn't make sense to build buildings big enough to need elevators. I mean, how would you get up and down the buildings? Answer: an elevator... but it didn't exist yet... hence, nobody could imagine how to g…
But of course cranes existed (on building sites, and in factories) since approximately the day after we invented the rope. But an elevator safe and reliable enough to make rich people buy an apartment above the 2nd floor? And cities dense enough that they were tempted to do so? Those took longer.
> (Some commenters have suggested that it was not obvious that a two-wheeled vehicle would balance, but I find this unconvincing given how many other things people have learned to balance on, from dugout canoes to horses themselves.) I'll be one of those commenters I guess.... What!?? Balancing in a canoe is in no way similar to a bicycle. I can jump in a canoe having never been in one, and it will balance itself. I…
If you saw off a disc-shaped slice from a log of wood, and it rolls a few meters, you experience first hand that a single wheel can balance itself. Some say this is how the wheel was invented in the first place [citation needed].
The physics of how a bicycle balances itself when you are moving is very different than that, complicated, and quite unintuitive. Basically when the bike starts to lean to one side, the rotation of the front wheel causes it to steer to move the bike underneath the direction you are leaning. This happens several times a second, and faster than a human can react.
https://www.citylab.com/design/2015/05/the-weird-wonderful-s...
>Yet it was a simple mechanical invention As a mechanical engineer, this statement baffled me. All manufactured technology exists in the context of the manufacturing capabilities available to the designer. The manufacturing tech had to be tremendously complicated before a decent bike could be made. Hollow steel tubes aren't simple. Ball bearings aren't simple. There is a reductionist viewpoint among "theory" people t…
Earlier quoted context omitted.
Yes, but I don’t think that was the factor here. Ancient technology was astoundingly precise (see the famous Antikythera mechanism). I think the problem was roads. If you combine bad (or nonexistent) roads with airless hard tires, the result is much much less useful than any modern bike on any modern road. The first bikes were indeed wooden with wooden wheels. No ball bearings, no hollow steel tubes etc. But streets.…
Would a wooden bicycle, with not-very-freely-spinning wheels, and a bone-jarring ride, be worth the considerable expense of purchasing? Would it even be better than walking and/or using a wheelbarrow? Doesn't the thing produced have to rise above a certain level of utility to merit making some copies of it? For human-scale power, I am not sure a bicycle without bearings or pneumatic tires works other than as a curios…
There was basically no rich middle class which had the time and money to fool around with individual transportation, and the other classes had either no real reason to want this or it was pure luxury.
Earlier quoted context omitted.
> As for ball bearings these are incremental improvements not a necessity (see horse chariots and carriages with wheels used for millenia before we had ball bearings). For another example see medieval wooden windmills - all cogs and bearings made from wood with some animal fat and skin for bushings and lubrication - worked well enough for centuries. ... >> Anyone accustomed to modern practice finds it hard to believe…
It would be less efficient, but still workable. Even just wood on wood is sufficient. Proof: https://www.youtube.com/watch?v=CcvFpbh2fjE [1] I think people vastly underestimate what you can do with very simple "naive" technology. [1] Yeah it uses aluminium spacers on the chain, but you can do a bicycle without a chain.
> https://www.youtube.com/watch?v=CcvFpbh2fjE
Your "proof" is unconvincing.
1. The bike looks super wobbly and seems like it takes a lot of effort to just make it function properly. Yes, it is an example of a wooden bicycle, but it is not an example of a useful wooden bicycle. It seems like it probably has a pretty short working life and low speed. In short, it's worse than just running.
2. The bike is being run on a paved road. All of my earlier criticisms get magnified by the stress of taking the bike off road. Yes, dirt roads are a thing. No, they are not nearly as smooth as asphalt. Also, much like carts, a bicycle like that would start to put ruts in a dirt road.
Earlier quoted context omitted.
Right. And one point that cannot be stressed enough. Good steel, in quantity, only goes back to 1880. Lots of things that "could have been built in antiquity" foundered on that basic fact. Before Bessemer, steel was as exotic as titanium is now. The alternatives are not good. Cast iron? Too heavy and too brittle. Wrought iron? Maybe, but not that great. Lead? Too soft. Brass? Could work, but expensive. A king's kid m…
Good steel would only be strictly needed for axles. Bearings could have been polished and oiled wood. The frame, wood. The hinge of the front wheel, brass or another small bit of steel. Transmission could be a leather belt. Wheels, wood again. Would such a device somehow emulate a modern bicycle? Very likely. Would such a device be practical, reliable, fast, to say nothing of comfort? I greatly doubt it.
I suspect you could make a perfectly acceptable modern bicycle with 18th century technology, albeit not as durable. Metal axles aren't much of a problem. Light and strong wheels are trickier, but you could get away with solid wooden ones, or emulate modern spoke systems with sturdy leather strands. The chain is difficult point - leather won't cut it as you need immense tensile strength and rigidity - but if you didn't want to meticulously hand-craft a modern chain (possible but tedious), a direct-gear solution might be practically possible.
No, what was missing was the very concept that it would be a worthwhile thing to attempt to build. It would have taken an incredible visionary to follow the above steps, especially in a world where the poor quality of roads made such a device of questionable value. And anyone rich enough to afford such a thing was doubtless rich enough to afford a horse carriage - who in that set would aspire to pedal through the mud?
tl;dr expensive, flimsy bicycles are completely useless in a world with poor roads and deep wealth inequality.
Earlier quoted context omitted.
Right. And one point that cannot be stressed enough. Good steel, in quantity, only goes back to 1880. Lots of things that "could have been built in antiquity" foundered on that basic fact. Before Bessemer, steel was as exotic as titanium is now. The alternatives are not good. Cast iron? Too heavy and too brittle. Wrought iron? Maybe, but not that great. Lead? Too soft. Brass? Could work, but expensive. A king's kid m…
I often wonder as I am building/fixing something (often my bicycle as it happens) and I happen to toss an extra screw in the trash how miraculous a simple screw of this type would have been to a middle-ages craftsman. The precision of keeping all those threads perfectly spaced is one thing, but the technology to make them in such volume at these sizes (often quite tiny), and in volumes so as to make them essentially…