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RE: [Geared_hub_bikes] chain tensioner or not

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  • Alex Wetmore
    There are 4 basic options for tensioning a non-derailleur drivetrain: * horizontal dropouts * vertical dropouts with chain tensioner * vertical sliding or
    Message 1 of 9 , Apr 10, 2013
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      There are 4 basic options for tensioning a non-derailleur drivetrain:
      * horizontal dropouts
      * vertical dropouts with chain tensioner
      * vertical sliding or pivoting dropouts
      * eccentric bottom bracket

      They each have good and bad points.

      Horizontal dropouts:
      Pros: Simple, low cost.
      Cons: They work poorly with rigid fenders and you have the re-tension the chain every time you remove the rear wheel. They can slide (jamming the wheel into the chainstays) under very high pedal pressure. Don't work well with disk brakes.

      Vertical dropouts with chain tensioner:
      Pros: Simple, pretty low cost. Fender alignment is easy. Easy to adapt to production bikes. Works well with disk brakes.
      Cons: Chain tensioner makes rear wheel removal and installation more annoying. Chain tensioner adds noise and weight. Only option that doesn't work with a chaincase.

      Eccentric BB and Sliding/Pivoting rear dropouts:
      Pros: Easy adjustment that stays fixed even as you remove the rear wheel. Works well with disk brakes. Works nicely with fenders (EBB is better than sliders here).
      Cons: Expensive, hard to retrofit to existing bikes, heavier than horizontals.

      I have IGH bikes with all 4 setups in my basement:
      * Touring Bike (Rohloff) : EBB
      * MTB1 (Rohloff) : EBB
      * MTB2 (Rohloff) : Chain tensioner
      * Mixte (wife's bike, Nexus 8) : Horizontals
      * Folding Bike 1 (Nexus 8) : Pivoting dropouts
      * Folding Bike 2 (3sp hub) : Tensioner
      * Commuter bike (Alfine) : Pivoting dropouts

      I've also owned 2 bikes with sliding dropouts, but don't have any at the moment.

      alex

      ________________________________________
      From: Geared_hub_bikes@yahoogroups.com [Geared_hub_bikes@yahoogroups.com] on behalf of bikealfa [mtwils@...]
      Sent: Wednesday, April 10, 2013 6:46 AM
      To: Geared_hub_bikes@yahoogroups.com
      Subject: [Geared_hub_bikes] chain tensioner or not

      None of my IGH bikes have chain tensioners. On all but one* the rear wheel moves in the dropout to adjust the chain tension.

      I know this has the disadvantage that the rear wheel needs to be moved periodically to keep the chain from falling off, but it has the advantage that the chain will not skip even with worn sprockets, and the additional advantage of simplicity.

      My not-so-humble opinion is that if I am going to use a chain tensioner, it might as well move sideways and also be a shift mechanism.

      I would be happy to read the pros of chain tensioners and IGH.

      Michael Wilson

      *The last is my only attempt to do the "magic ratio" thing; it does not work the way I want and will probably come apart again.



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    • Colin Bryant
      In my case, I ride a recumbent, so the chain tensioner allows me to make X-seam (leg length, by adjusting the fore/aft BB position) adjustments, without
      Message 2 of 9 , Apr 10, 2013
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        In my case, I ride a recumbent, so the chain tensioner allows me to make X-seam (leg length, by adjusting the fore/aft BB position) adjustments, without necessitating chain length changes on a bike that has vertical dropouts.
         
        --

        Colin

         


        From: bikealfa <mtwils@...>
        To: Geared_hub_bikes@yahoogroups.com
        Sent: Wednesday, April 10, 2013 6:46:58 AM
        Subject: [Geared_hub_bikes] chain tensioner or not

         
        None of my IGH bikes have chain tensioners. On all but one* the rear wheel moves in the dropout to adjust the chain tension.

        I know this has the disadvantage that the rear wheel needs to be moved periodically to keep the chain from falling off, but it has the advantage that the chain will not skip even with worn sprockets, and the additional advantage of simplicity.

        My not-so-humble opinion is that if I am going to use a chain tensioner, it might as well move sideways and also be a shift mechanism.

        I would be happy to read the pros of chain tensioners and IGH.

        Michael Wilson

        *The last is my only attempt to do the "magic ratio" thing; it does not work the way I want and will probably come apart again.



      • pj
        ... Add to this rear facing track ends. ... Living with a couple of IGH bikes with rear facing track ends, I
        Message 3 of 9 , Apr 11, 2013
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          Alex wrote:
          >
          > There are 4 basic options for tensioning a non-derailleur drivetrain:
          > * horizontal dropouts
          > * vertical dropouts with chain tensioner
          > * vertical sliding or pivoting dropouts
          > * eccentric bottom bracket

          Add to this rear facing track ends.

          <http://sheldonbrown.com/gloss_dr-z.html#dropout>

          > Vertical dropouts with chain tensioner:

          > Cons: Chain tensioner makes rear wheel removal and installation more annoying.

          Living with a couple of IGH bikes with rear facing track ends, I think I'd rather take the rear wheel off an IGH bike with vertical dropouts and a chain tensioner (depending on the details of tensioner geometry).

          Gunnar argued that verticals + chain tensioner wasn't such a bad set-up:

          <http://gunnarbikes.com/site/2011/10/internal-vertical/>

          pj
        • Alex Wetmore
          Yes. Rear facing track ends are such a terrible idea for a IGH/commuter type bike that I had forgotten about them. Verticals + tensioner isn t so bad, it just
          Message 4 of 9 , Apr 11, 2013
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            Yes. Rear facing track ends are such a terrible idea for a IGH/commuter type bike that I had forgotten about them.

            Verticals + tensioner isn't so bad, it just isn't as good as EBB or sliding/pivoting dropouts. I see it as about equal to horizontals, better in some ways and worse in others.

            alex
            ________________________________________
            From: Geared_hub_bikes@yahoogroups.com [Geared_hub_bikes@yahoogroups.com] on behalf of pj [prester_john_in_cathay@...]
            Sent: Thursday, April 11, 2013 6:00 AM
            To: Geared_hub_bikes@yahoogroups.com
            Subject: [Geared_hub_bikes] Re: chain tensioner or not

            Alex wrote:
            >
            > There are 4 basic options for tensioning a non-derailleur drivetrain:
            > * horizontal dropouts
            > * vertical dropouts with chain tensioner
            > * vertical sliding or pivoting dropouts
            > * eccentric bottom bracket

            Add to this rear facing track ends.

            <http://sheldonbrown.com/gloss_dr-z.html#dropout>

            > Vertical dropouts with chain tensioner:

            > Cons: Chain tensioner makes rear wheel removal and installation more annoying.

            Living with a couple of IGH bikes with rear facing track ends, I think I'd rather take the rear wheel off an IGH bike with vertical dropouts and a chain tensioner (depending on the details of tensioner geometry).

            Gunnar argued that verticals + chain tensioner wasn't such a bad set-up:

            <http://gunnarbikes.com/site/2011/10/internal-vertical/>

            pj



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          • David Dannenberg
            Nice summary. There are several EBBs on the market that are made to fit standard bottom brackets.
            Message 5 of 9 , Apr 11, 2013
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              Nice summary. There are several EBBs on the market that are made to fit standard bottom brackets.
            • Doug Litchfield
              While I would agree that the most elegant and durable solution for a single chainwheel/hub configuration is horizontal dropouts. My new favorite (read most
              Message 6 of 9 , Apr 11, 2013
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                While I would agree that the most elegant and durable solution for a single chainwheel/hub configuration is horizontal dropouts.
                My new favorite (read most recent) set up is hybrid gearing: 48/44 in front with a front der; 18t Sturmey AW and Alfine tensioner in back.
                A nice even spread.
                It'll be something else next year!

                D.


                On Wed, Apr 10, 2013 at 7:46 AM, bikealfa <mtwils@...> wrote:
                 

                None of my IGH bikes have chain tensioners. On all but one* the rear wheel moves in the dropout to adjust the chain tension.

                I know this has the disadvantage that the rear wheel needs to be moved periodically to keep the chain from falling off, but it has the advantage that the chain will not skip even with worn sprockets, and the additional advantage of simplicity.

                My not-so-humble opinion is that if I am going to use a chain tensioner, it might as well move sideways and also be a shift mechanism.

                I would be happy to read the pros of chain tensioners and IGH.

                Michael Wilson

                *The last is my only attempt to do the "magic ratio" thing; it does not work the way I want and will probably come apart again.


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