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  1. #1
    !BAMBOO! Contour's Avatar
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    A single adjustable gear?

    Last night I was thinking of idea's to simplify the gearing of a bike. I came up with a concept of a single adjustable gear. After thinking and doing a little research today I found this which appears to my cover my concept. Now my question has a design like this or the concept actually ever been implemented into any bikes (custom or otherwise). Are there flaws with the concept or that design in particular that I may be over looking? Also what do you think of the concept, assuming there was a design that could implement it well.

  2. #2
    Senior Member johnknappcc's Avatar
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    I don't know about it, but an IGH is a much better solution, and you can get a nice one for a pretty good price.

  3. #3
    !BAMBOO! Contour's Avatar
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    To clarify, this isn't so much about the other options rather this particular concept and how it may be implicated.

  4. #4
    Senior Member mzeffex's Avatar
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    There is Truvativ's hammershmidt.
    Quote Originally Posted by rjones28 View Post
    Are they talking about spectators feeding the cyclists? You know, like don't feed the bears?

  5. #5
    slow as I ever was Ex Pres's Avatar
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    One gear is better.

    FIX your bike.

  6. #6
    headtube. zzyzx_xyzzy's Avatar
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    Expanding chainwheels have been invented a lot of times. The problem is that a bike's chain tension is so great that a mechanism that can change the effective chainwheel size while standing up to the stress winds up being very heavy. The book to read if you're interested about all the crazy things that have been tried for bicycle gearing is "the Dancing Chain" by Frank Berto.

  7. #7
    punk kid.
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    i forget what the name is but there is a company in sandiego that just came out with an infinite gear hub. they make the transmissions for ford hybrids. its really trippy to ride.

  8. #8
    Insane Bicycle Mechanic Jeff Wills's Avatar
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    Quote Originally Posted by rs1101 View Post
    i forget what the name is but there is a company in sandiego that just came out with an infinite gear hub. they make the transmissions for ford hybrids. its really trippy to ride.
    Nuvinci: http://www.fallbrooktech.com/Nuvinci.asp
    Jeff Wills

    All my bikes.

  9. #9
    headtube. zzyzx_xyzzy's Avatar
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    snips out of The Dancing Chain...
    Attached Images Attached Images

  10. #10
    shut up and ride
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    i rode a nuvinci equipped bike at interbike. it's a pretty cool system but somewhere else on the board some said the the nuvinci hub weighs 9 pounds. when i picked up the bike it sure felt like that is true.

  11. #11
    Perineal Pressurized dobber's Avatar
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    Are we trying to reinvent the wheel again?
    This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.

  12. #12
    Gear Hub fan
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    Quote Originally Posted by zzyzx_xyzzy View Post
    snips out of The Dancing Chain...
    As noted it has been invented and tried again and again. Some have even made it to market briefly I believe. None have succeeded. Problems have been weight and complexity as well as having moving parts subject to dirt and wear due to the high loads involved. Remember that at the chainwheel the mechanism has to withstand the full torque of a standing rider while a geared hub has that reduced by the primary drive ratio, normally at least 2 to 1. That reduces torque loads by half or more for the IGH.

    Interesting bike transmission concepts are well covered in "The Dancing Chain" as well as in the second and third editions of "Bicycling Science" published by MIT. I have the recently published third edition of "The Dancing Chain" and can highly recommend it. It is available from Amazon for less than 2/3 the list price. If more bike drivetrain "inventors" read the books then they would save a lot of skull sweat
    Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro

    Visit and join the Yahoo Geared Hub Bikes group for support and links.
    http://groups.yahoo.com/group/Geared_hub_bikes/

  13. #13
    !BAMBOO! Contour's Avatar
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    Thanks for all the replies and suggestions. I'll definitely check out the Dancing Chain book and the Bicycling Science one as well.

  14. #14
    Pleasurable Pain greyghost_6's Avatar
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    Trek actually did some research in this area and came out with theoretically infinite gear stepping It was belt driven so it probably wouldn't be included in "The Dancing Chain" haha. But I found an entire bike with this setup selling for all of $300 3 or so years ago. I guess since there is not much market for something this exotic, only a collector would buy it. The mechanics of it appeared to take up a good half of the center of the wheel and weigh probably 15 pounds. At this point in time, anything you would gain in performance you would loose in servicability and complexity.
    I had to re-learn how to walk once, but never needed to re-learn how to ride a bike. Cyclist for life.

  15. #15
    I suck, but you're worse
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    Eliminate the chainwheel and go drive shaft

  16. #16
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    Quote Originally Posted by zzzwillzzz View Post
    i rode a nuvinci equipped bike at interbike. it's a pretty cool system but somewhere else on the board some said the the nuvinci hub weighs 9 pounds. when i picked up the bike it sure felt like that is true.
    I was wondering how heavy a thing like that would be. 9 pounds for the rear hub alone is about 30-40% of the typical cruiser weight. Add that on top of the bike weight. Oh, well, you'll get your exercise riding this thing!

  17. #17
    Senior Member Torchy McFlux's Avatar
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    Quote Originally Posted by sooprvylyn View Post
    Eliminate the chainwheel and go drive shaft
    Driveshafts are 10-15% less efficent at transmitting energy than chains are.

  18. #18
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    You can always install a rat in a exercise wheel, and vary your speed by adjusting his feed?

  19. #19
    Elitist Troglodyte DMF's Avatar
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    I.e. vary his amphetamine drip rate. And spare rats are cheap and fairly light.
    Stupidity got us into this mess - why can't it get us out?

    - Will Rogers

  20. #20
    Senior Member
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    Quote Originally Posted by sooprvylyn View Post
    Eliminate the chainwheel and go drive shaft
    It's been done, starting in the 1890's.

    Heavy, mechanically inefficient and, for more than one gear, it's only usable with internal geared hubs which add their own level of inefficency.

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