Subject:
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Re: building a bicycle -- can it be done?
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Newsgroups:
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lugnet.loc.au
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Date:
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Fri, 1 Sep 2000 14:18:28 GMT
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Viewed:
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442 times
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In lugnet.loc.au, Geoffrey Hyde writes:
> The biggest problem you will find is that each LEGO Technic gear is one
> brick wide, except for the smallest one which is slightly more than a brick
> wide.
You mean the thinnest tech gear which is about 1/2 a brick wide? :) (the thin
bevel gear, that is-- too bad they don't make 1/2 brick wide chain!)
> Set up four or five of these side by side and your bicycle is going
> to look more like an overweight elephant should be using it!! ;-)
Perhaps you could build a FUNCTIONAL one that wasn't "accurate" with a
transmission and separate chains? 'Course that'd be cheating :)
> The other problem, even if this first one could be overcome is how to
> compensate for the sideways forces acting upon the chain links, they weren't
> exactly designed to swing from side to side much. Maybe enough for a small
> amount of swing, given that you incorporate enough links into the chain, but
> for one as large as five studs I would expect more than a few snapped or
> broken links to result, unless using an unrealistically long chain.
Perhaps a 2-geared bicycle would be possible by setting the 'pedal' gear 1/2 a
stud off from the 2 rear wheel gears, thus reducing the amount of side to side
motion that would have to be handled by the chain...
Alternatively, making the pedal gear an equal number of gears to the rear
wheel gears, and making the derailleur work on both sets might also work.
Hence, the chain never actually bends from side to side-- although this
probably makes it more difficult to create the derailliur, since operating
both pedal and wheel derailleurs at once makes for a stretched chain...
> I can quite imagine the gear part for the derailleur mechanism at the back,
> though, that would be simple enough to do with a few Technic LEGO pieces.
Agreed-- the mechanism to actually move the chain would be fairly
straightforward...mostly just difficult to work from the handlebars, but that
could be worked out without phenomenal difficulty.
> > How would I get the bike to coast, or would the pedals have to turn with
> > the wheels?
I thought about this one a bit, and I think it might be possible using a
somewhat non-conventional locking mechanism. Of course I'm not a regular
technic builder, so there might be easier ways to do it, but I've used the
locking mechanism as borrowed from 6949 (Spyrius Robo-Guardian). Rather hard
to describe-- I also used it in my portcullis design for my castle so it would
lock in place (and not fall down) when being hoisted, while still going up
smoothly-- I took a photo at:
http://www.suave.net/~dave/images/newgate/newgatelocker.jpg
But in order for that to work, you would have to attach the locking piece to
the rear gear wheels, and let the actual axle to the wheel be free from the
gear wheels. Additionally, since you might have to work against gravity, you'd
have to put rubber bands on the locking piece to make sure it would lock when
needed...
At any rate, this would allow the mechanism to work similarly to a real
bicycle: When the pedals were turned, the rear wheel would go forward, but
when the rear wheel turned and the pedals remained still (or were going slower
than the rate of the rear wheels), the pedals wouldn't be forced to turn.
Additionally, when backing up, the pedals would be forced to turn backwards...
Of course this is all just speculation at this point, but it's certainly an
inspiring project :)
DaveE
p.s is there a reason this was posted to lugnet.loc.au? It would probably get
a much better response from lugnet.technic, lugnet.general, or lugnet.build...
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Message has 1 Reply:
 | | Re: building a bicycle -- can it be done?
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| David Eaton <deaton@intdata.com> wrote in message news:G07p2s.MF8@lugnet.com... (...) brick (...) thin (...) No, I said smallest. Bevel gears aren't the smallest. :) (...) Possibly. but it would be fun trying methinks. (...) weren't (...) small (...) (24 years ago, 1-Sep-00, to lugnet.loc.au, lugnet.technic)
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Message is in Reply To:
| | Re: building a bicycle -- can it be done?
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| The biggest problem you will find is that each LEGO Technic gear is one brick wide, except for the smallest one which is slightly more than a brick wide. Set up four or five of these side by side and your bicycle is going to look more like an (...) (24 years ago, 1-Sep-00, to lugnet.loc.au)
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