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  1. #1
    ppc
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    Amazingly clever shift-once two-speed fixie drivetrain arrangement from the 80s

    I just came across this page that deals with the bizarre idea of running two chains on a bike, when I read the following nugget at the end of the page:

    However it got me thinking about another bike I'd seen with a similar set-up but this one made a lot of sense. In 1982 Canadian rider Jocelyn Lovell rode the kilometre time trial at the World Championships in Leicester, England using a bike with two transmissions. His arrangement gave him two gear ratios, a lower gear to get away from the line and a higher gear that kicked in after about seventy metres. His ride in Leicester wasn't as good as he hoped for but the transmission worked well and it could not be faulted by the UCI commisaires.



    Jocelyn's bike had a freewheel sprocket on the normal right hand side and a fixed sprocket on the left hand side. As he moved away from the line he drove through the RH sprocket and the left hand fixed sprocket began to unscrew from the hub. It being of smaller diameter it turned at a slower rate than the RH sprocket and being on the "wrong side" of the hub it would naturally unscrew. After about seventy metres the LH fixed sprocket came up against the lockring and at that point drive was through the LH side and the RH sprocket freewheeled. The distance traveled before the higher gear engaged could be adjusted by setting the position of the lockring. The bigger the space between lockring and sprocket at the start the longer the distance before the higher gear engaged.
    Jocelyn experimented for some considerable time to come up with a combination of sprockets and chainrings that would not only give two suitable ratios but that would need chain lengths that would be at the correct tension. He settled on a low gear of 42x13 (87.2") and a high gear of 53x15 (95.4")


    Wow, that is incredibly clever and a very elegant working around (or within?) the UCI rules. Lovell was a genius. I'm almost tempted to try it myself to see what it feels like

    (There's just a small misunderstanding of how the system worked in the above explanation: the LH sprocket unscrews because it is smaller and thus spins *faster* than the wheel in the first 70m, not slower)

  2. #2
    Elitist carleton's Avatar
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    That's pretty ingenious.

    I've seen a double freewheel setup using a standard freewheel on the right side of the cranks combined with a LSD (left side drive) BMX freewheels for the left side setup.

    LSD exists because some BMXers want the chainring on the left side to get it out of the way if they like to do grinding tricks on the right side.

  3. #3
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    Quote Originally Posted by carleton View Post
    That's pretty ingenious.

    I've seen a double freewheel setup using a standard freewheel on the right side of the cranks combined with a LSD (left side drive) BMX freewheels for the left side setup.

    LSD exists because some BMXers want the chainring on the left side to get it out of the way if they like to do grinding tricks on the right side.
    Nahhh man, LSD exists to bring us all together.... man.
    1988 Miele Azsora

  4. #4
    Hi, I'm Bryan. jimmytango's Avatar
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    damn jets, you beat me to it lol.
    I am not the company I keep.

  5. #5
    Senior Member seau grateau's Avatar
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    Interesting. Any video of this in action?
    Quote Originally Posted by adriano View Post
    thanckx.
    Quote Originally Posted by Nagrom_ View Post
    "I made love to your mother dozens of times last week, and she doesnt know what a worn chain ring looks like"

  6. #6
    I Like to Bike youngandcurious's Avatar
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    http://www.youtube.com/watch?v=hSoMkOhvaUQ three chains, three chain rings,three cogs!
    Quote Originally Posted by mikeetow View Post
    id ride it. after making it a fixed gear

  7. #7
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    tempted to try this

  8. #8
    * adriano's Avatar
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    if every edge really mattered, why would you want to uselessly spin a freewheel for the bulk of the race?

  9. #9
    Senior Member rustybrown's Avatar
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    More of an edge gained by quicker acceleration.

  10. #10
    * adriano's Avatar
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    did he win?

  11. #11
    Senior Member rustybrown's Avatar
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    Everybody wins in a TT

  12. #12
    extra bitter kyselad's Avatar
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    Quote Originally Posted by youngandcurious View Post
    http://www.youtube.com/watch?v=hSoMkOhvaUQ three chains, three chain rings,three cogs!
    But unrelated to the setup described by the OP as far as I can tell. What would be the point of such an apparently identical and redundant drivetrain, anyway?

  13. #13
    Senior Member polobreaka's Avatar
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    funny, my bro and i were just joking talking about putting on 2 cranks and 2 cogs just for kicks when i was changing out my drivetrain.

  14. #14
    Senior Member ph4nt0mf1ng3rs's Avatar
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    Quote Originally Posted by kyselad View Post
    But unrelated to the setup described by the OP as far as I can tell. What would be the point of such an apparently identical and redundant drivetrain, anyway?
    More surface area contact with the mechanism driving the wheel forward? Kind of like the idea between turning a rolling-pin pulley with a string, vs pulling it with a wide belt.

    Or something like that.

    I dont know Im just making a hypothesisisisness.
    Quote Originally Posted by Vixtor View Post
    Seriously, I wouldn't trust it at all.

    phatomfingers would be interested in this.

  15. #15
    Senior Member chenghiz's Avatar
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    Quote Originally Posted by ph4nt0mf1ng3rs View Post
    More surface area contact with the mechanism driving the wheel forward? Kind of like the idea between turning a rolling-pin pulley with a string, vs pulling it with a wide belt.
    This would only be useful if a single chainring/cog was slipping, which it wouldn't be. I imagine the triple chainring/cog setup is just a vanity thing.

  16. #16
    ppc
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    3 chains on one side are useless, and so are 2 chains on both sides. One chain is plenty strong to withstand the effort of any cyclist. Mechanically, only one cog can be fully screwed onto the hub, and only one of the chains can be fully engaged anyway.

    So yes, it's all vanity.

  17. #17
    I Like to Bike youngandcurious's Avatar
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    Quote Originally Posted by kyselad View Post
    But unrelated to the setup described by the OP as far as I can tell. What would be the point of such an apparently identical and redundant drivetrain, anyway?
    Hmm i posted because it has multiple drive chains i guess and there is no benefit...
    Quote Originally Posted by mikeetow View Post
    id ride it. after making it a fixed gear

  18. #18
    Senior Member vw addict's Avatar
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    Quote Originally Posted by adriano View Post
    did he win?
    but r u going to the alleycat? bring your under armor, and aerospokez

  19. #19
    * adriano's Avatar
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    i need a left side freewheel for a fast start.

  20. #20
    Antarctica awaits WoundedKnee's Avatar
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    When I brought my double freewheel to my lbs, he said back in the 80s or 90s some BMX racers had double freewheels with some kind of "shift once" mechanism to get a quick start. That's what I thought you were talking about.

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