What on earth?
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What on earth?
Postby cludence » Mon Feb 11, 2008 10:18 pm
Well today I was cleaning up and stripping some bikes and got to this mountain bike which had some wierd bits on the rear wheel. I thought it must have been some generator setup until I looked closer and realized it is the gear thing he mentioned! There is a single chainring on the front of the bike, no shifters or deraileurs anywhere. I am guessing there are some pieces missing but here is a pic of the wheel. It appears to move down over the individual rings on the cluster.
So yet another thing for me to play around with on a rainy day.
Karen.
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Postby ukalipt » Mon Feb 11, 2008 11:18 pm
without any prior knowledge it is going to be so hard to work out what is missing.
auto geared bikes are available from land rider bicycles
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Re: What on earth?
Postby twowheels » Mon Feb 11, 2008 11:25 pm
Do you have a photo of the rear wheel attached to the bike showing There is a single chainring on the front of the bike, no shifters or deraileurs anywhere. ?cludence wrote:I was talking to a gentleman on Saturday who mentioned he had heard about a bike in the 80's that automatically changed gears for you. He said it must have been a novelty thing as he had never seen one.
Well today I was cleaning up and stripping some bikes and got to this mountain bike which had some wierd bits on the rear wheel. I thought it must have been some generator setup until I looked closer and realized it is the gear thing he mentioned! There is a single chainring on the front of the bike, no shifters or deraileurs anywhere. I am guessing there are some pieces missing but here is a pic of the wheel. It appears to move down over the individual rings on the cluster.
So yet another thing for me to play around with on a rainy day.
Karen.
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Postby cludence » Mon Feb 11, 2008 11:36 pm
Stupid me didnt notice until I had stripped the frame. Rear dropout was bent so it was headed to be used to make a wheelchair. It wont be now. I will straighten the dropout as best I can and put it back together and hopefully work it out. Will make a great display bike. I wouldnt trust riding it too far unless I get the rear dropout completely replaced.
Karen.
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Postby Mulger bill » Tue Feb 12, 2008 12:57 am
I love this sorta stuff, wish I could hang around your shed when you strip it down. More pics, pretty please
I'm guessing the rear mech is only a chain tensioner and has a fairly weak paralellogram spring (sp), does it have cable fittings? Are those grey lumps on the spokes fixed or mobile? It looks like the arms extending from the LH hub flange might have been attached to the lumps One last question before I shut up... the grey ring around the cassette, Is that chainscarring on it?
Cheers
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Postby cludence » Tue Feb 12, 2008 1:09 am
Karen.
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Postby Kid_Carbine » Tue Feb 12, 2008 9:03 am
The 'derailleur' uses a light spring to load it towards the wheel
The three objects in the spokes are weights that slide outwards or inwards along the spokes. They are linked via a bell crank to three horizontal shafts that push the ring with the chain marks outwards towards the smallest sprocket.
A light spring, or springs, brings the ring back towards the spokes. When the wheel is turning slowly, the weights on the spokes are pulled in towards the hub by the light springs, the laterally moving ring retracts to the default position as per the photo's & the 'derailleur' moves the chain to the default position on the largest sprocket by virtue of its spring loading.
As the rider moves off, the weights, through centrifugal force, overcome the spring loading of the dérailleur & any retaining springs that they might have & move towards the rim, along the spokes.
The 'ring' is then pushed outward & derails the chain to the next smallest sprocket. [Hard to see how a ring like this could do it] In this next higest gear speed increases, the weights, now with an effective increase in operating diameter & with increased speed, pull outward even harder, pushing the chain, via the mechanism, onto the next fastest sprocket, & so the cycle continues, reversing this process as the speed diminishes, with the spring loaded dérailleur sending the chain back up onto the next largest sprocket.
It may, or may not be significant that the 'ring' has a wave shape to it.
The alternative is that the ring is actually bent in the picture, but normally engages in a slot fitting in the 'dérailleur' & pushes or pulls it laterally effecting the change of gear in both directions.
I have no idea how it would 'index' on each sprocket position.
More pictures or a look-see will give me a better idea of the exact function, but it's easy to see why it's such a popular item.
Now that's AUSTRALIAN to the core.
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Postby Mulger bill » Tue Feb 12, 2008 12:10 pm
Kid, I think you've nailed it, thanks once again.
Shaun
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Postby stevendavid75 » Tue Feb 12, 2008 11:32 pm
Clearly the idea never worked well enough to get into any real mainstream production, as such we can try as hard as we like to figure out how it worked, My idea is that it probabaly didnt!!
Could it not have been a possible training tool like we see in the the wheels of the stationary trainong bike that has fan like things attached to the spokes? could this have been a road going initiative?
lastly, I have ridden a few bikes over the years that have changed gears without actually touching the lever, bloody frustrating actually
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Back Wheel !!!
Postby Recycler » Wed Feb 13, 2008 12:17 pm
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Postby mikeg » Wed Feb 13, 2008 1:17 pm
The disk looks to be out of shape and should be flat and true. The derailer looks like it would be the original one. The grey wheel without teeth is the key, and it looks like a low-normal derailer, that is springs to rest at the lowest gear. The grey wheel rests against the disk, or against the low limit screw. When stopped the weights are closest to the hub, and the disk fully retracted to the spokes. As the speed increases the weights move closer to the rim, and progressively push the derailler outwards, thus changing to a higher gear. On slowing down, the weights move back towards the hub, and the derailer spring aids this and changes to lower gears.
What goes against this mechanism is that it needs an indexing system to make it resist changing until enough force (potential) is available to overcome a detent of sorts, and it moves to the next index position.
Tuning the existing setup would require an adjustment to give the right change points for good cadence ranges.
From initail looks it may fit to any frame.
It would be interesting to see if it could be made to work again. You could sit the bike in a tune up stand or trainer, and see the operation.
Without some indexing system, a rider would have to pedal at a constant cadence to stay in one gear, increase rapidly until gear change occurs and ease off to allow the chain to settle, and then resume pedalling.
It may be possible to fit to another wheel.
I would be interested having a look at it closer Karen
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Postby mikesbytes » Wed Feb 13, 2008 1:18 pm
Is the spring direction in the rear derailer reversed?sogood wrote:It can push the chain down the cogs but how can the chain come back up?
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Postby Kid_Carbine » Thu Feb 14, 2008 2:32 am
The third wheel engages with this disk & the dérailleur is spring loaded toward the wheel so that as the bike slows, the lowest gear [largest sprocket] is engaged.
There must surely be some sort of indexing system otherwise the clatter of a misaligned chain would be a source of constant irritation.
I suspect that this must have been an idea whose time came, ........ & went, over a time span about the same as a camera flash.
There was a crankset made available in the early 80's that used a segmented chainwheel that enlarged or shrunk in diameter 'automatically' as you rode to provide the right gear ratio for every eventuality. It looked mechanically complex & it was expensive from memory. Push on magazine had a feature on it. Anybody ever seen one?
No? Neither have I. Must have been another technological breakthrough that failed to capture the imagination of the cycling masses. Imagine the two of these items on the same bike. No, perhaps it's an image I don't really want to contemplate.
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Postby mikesbytes » Thu Feb 14, 2008 10:46 am
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Postby cray- » Thu Feb 14, 2008 4:32 pm
If it wasn't Beyond 2000 then it was a little doco I taped off of Channel 9's Wide World of Sports about the history of Mountain Biking. They showed some grainy footage of people bashing down hills in the states on "Clunkers". Curvey Schwinn frames with knobby tyres. It then went on to show Gary Fisher on an early swing arm rear suspension system[ red frame, yellow arm] riding down some stairs. This was all around the early 90's I think. Rock Shox and Manitou forks where only just coming on to the market.
The more that I think about it, the more I'm convinced it was Beyond 2000 though. hell maybe the doco was actually a beyond 2000 segment and no WWoS at all. Meh.....either way.
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Postby Kid_Carbine » Thu Feb 14, 2008 10:37 pm
Agreed, but in some ways I suspect that it's a self defeating exercise in that the sort of person that would buy such a thing usually buys on price. The cheaper the better, which means that there is really no market for a well developed, properly made system since anything good usually costs money.mikesbytes wrote:There would be a market for some form of automatic gears, not for the likes of us though.
If you're going to spend any real money, you may as well get a real bike & do it properly.
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Postby timbo » Fri Feb 15, 2008 5:37 am
This might predate the rear deraillier by quite a bit, but with a name like the Canada Cycle Company and Autocycle on the frame, it makes me wonder if he later branched out into bicycles with small motors attached (a basic moped) and the strange bits and pieces had something to do with a drive mechanism for the motor and rear wheel.
Its all just a guess mind you, does the frame look like it may have had a motor attachment at some time?
Yes or no, its still interesting.
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Postby kukamunga » Fri Feb 15, 2008 9:57 am
*Had. Shimano introduced their 'AUTO D System' to work with their 'Inter-4 Hub' around 1999/ 2000 (have misplaced my '99/'00 Shimano catalogues ). Giant (and maybe Avanti?) released their 'Comfort Auto D' bikes in 2000, only to have them totally disappear from their 2001 range. No sign of 'Auto D' in the 2002 Shimano catalogue (or since). Hmmm.....cludence wrote:If my memory is correct, shimano has* some sort of automatic hub gear system
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