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Re: speculation on the future of belt drive

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  • Rich
    Joseph; It has been done for several downhill MTB transmissions made both in Europe and by SR Suntour in Taiwan. The design standard for frames to accomodate
    Message 1 of 29 , Feb 28, 2010
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      Joseph;

      It has been done for several downhill MTB transmissions made both in Europe and by SR Suntour in Taiwan. The design standard for frames to accomodate them has been public domained I believe and the transmissions made fit the same frames. The one European bike I saw listed that used it was about 6000+ Euros in Europe and weighed 35+ pounds.

      Disadvantages are weight and size as the transmission has to withstand full crank torque while a IGH has the input torque stepped down by the input ratio used. The SR Suntour version weighs about the same as the NuVinci hub or a bit more. It uses more of a motorcycle style multi shaft gearbox technology design than a IGH planetary gear technology.

      Here is a link to the SR Suntour version description.

      http://www.srsuntour-cycling.com/SID=sie0bcffa87ac6699555b6bef02f71a1/index.php?screen=sh.detail&tnid=2427

      Bottom bracket gearbox designs have always suffered from having to withstand full rider torque input. This has required much larger parts than needed for rear hub gearing arrangements.

      Rich Wood


      --- In Geared_hub_bikes@yahoogroups.com, Joseph Shaul <spasticteapot@...> wrote:
      >
      > I'm of the opinion that a gearbox on the bottom bracket would make a lot
      > more sense. I'm no expert on transmissions, but I'm fairly sure that a
      > single larger cog rotating slowly would be more efficient than several
      > smaller cogs rotating quickly - it certainly works well for mopeds. If
      > nothing else, the lack of size restrictions would help quite a bit.
      >
      > You can see what I'm getting on about here:
      > http://images.google.com/imgres?imgurl=http://www.scooterrestorations.com/media/img/illustrations/4/L.gif&imgrefurl=http://www.scooterrestorations.com/lambretta/sec-4-gearbox-kickstart/&usg=__qYCWy95PKcknwc8Fdzu1ugP_uO0=&h=480&w=776&sz=66&hl=en&start=2&um=1&itbs=1&tbnid=madZJyvh1rs82M:&tbnh=88&tbnw=142&prev=/images%3Fq%3Dmoped%2Bgearbox%26um%3D1%26hl%3Den%26sa%3DN%26tbs%3Disch:1
      >
      > On Sun, Feb 28, 2010 at 2:05 PM, Rich <astronut1001@...> wrote:
      >
      > >
      > >
      > > Bernard;
      > >
      > > I find it difficult to picture a variable diameter pulley that will work
      > > with a cogged timing belt as used on some bicycles and motorcycles
      > > currently. They work fine for V belt power transmission as used on
      > > snowmobiles and in industry. V belts and timing belts are different critters
      > > however.
      > >
      > > Same problems as doing a variable diameter chain sprocket. They have been
      > > done in the past but they are complex, heavy and expensive to both make well
      > > and provide good reliability.
      > >
      > > Separately controlled variable diameter pulleys would require a quite
      > > strong belt tensioner of some sort. Typical V belt variable transnissions
      > > have one pulley controlled by a speed or RPM sensor and the other spring
      > > loaded to open and close as required to maintain correct belt tension.
      > >
      > > The derailleur system has survived due to being inexpensive to make, light
      > > weight and surprisingly efficient. It is also easy to understand and adjust
      > > or repair.
      > >
      > > Rich Wood
      > >
      > >
      > > --- In Geared_hub_bikes@yahoogroups.com<Geared_hub_bikes%40yahoogroups.com>,
      > > "bernard.morey" <bernard@> wrote:
      > > >
      > > >
      > > > --- In Geared_hub_bikes@yahoogroups.com<Geared_hub_bikes%40yahoogroups.com>,
      > > David Dannenberg <ddannenberg@> wrote:
      > > > >
      > > > > My experience is that chains are always filthy no matter what they are
      > > lubed with. That and rusty. If chains were superior, they would not have
      > > been replaced by belts in so many industrial applications. Obviously there
      > > are advantages and disadvantages to each. If a particular belt width and cog
      > > spacing becomes universal--as has chain size more or less--then I think we
      > > will see more and more of them, with many sizes available much like fan
      > > belts. True, the volume generated by the bicycle market is much smaller than
      > > the automotive market, but I still suspect that the belt could become
      > > ubiquitous. Match a belt with a Rohloff and a bb gearset like a Schlumpf and
      > > it seems to me you would have a clean durable very low maintenance set-up
      > > with as many gears as anyone could possibly want.
      > > > >
      > > > > David Dannenberg
      > > >
      > > > Quite so. A speculation: the next step will surely be a belt-based
      > > continuously variable transmission for bikes with variable pulleys at the
      > > front and rear controlled by individual twist controls.
      > > >
      > >
      > >
      > >
      >
    • Joseph Shaul
      I m surprised that the gearboxes are so heavy - I would think they would be lighter.
      Message 2 of 29 , Mar 1, 2010
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        I'm surprised that the gearboxes are so heavy - I would think they would be lighter.

        On Mon, Mar 1, 2010 at 1:51 AM, Rich <astronut1001@...> wrote:
         

        Joseph;

        It has been done for several downhill MTB transmissions made both in Europe and by SR Suntour in Taiwan. The design standard for frames to accomodate them has been public domained I believe and the transmissions made fit the same frames. The one European bike I saw listed that used it was about 6000+ Euros in Europe and weighed 35+ pounds.

        Disadvantages are weight and size as the transmission has to withstand full crank torque while a IGH has the input torque stepped down by the input ratio used. The SR Suntour version weighs about the same as the NuVinci hub or a bit more. It uses more of a motorcycle style multi shaft gearbox technology design than a IGH planetary gear technology.

        Here is a link to the SR Suntour version description.

        http://www.srsuntour-cycling.com/SID=sie0bcffa87ac6699555b6bef02f71a1/index.php?screen=sh.detail&tnid=2427

        Bottom bracket gearbox designs have always suffered from having to withstand full rider torque input. This has required much larger parts than needed for rear hub gearing arrangements.

        Rich Wood



        --- In Geared_hub_bikes@yahoogroups.com, Joseph Shaul <spasticteapot@...> wrote:
        >
        > I'm of the opinion that a gearbox on the bottom bracket would make a lot
        > more sense. I'm no expert on transmissions, but I'm fairly sure that a
        > single larger cog rotating slowly would be more efficient than several
        > smaller cogs rotating quickly - it certainly works well for mopeds. If
        > nothing else, the lack of size restrictions would help quite a bit.
        >
        > You can see what I'm getting on about here:
        > http://images.google.com/imgres?imgurl=http://www.scooterrestorations.com/media/img/illustrations/4/L.gif&imgrefurl=http://www.scooterrestorations.com/lambretta/sec-4-gearbox-kickstart/&usg=__qYCWy95PKcknwc8Fdzu1ugP_uO0=&h=480&w=776&sz=66&hl=en&start=2&um=1&itbs=1&tbnid=madZJyvh1rs82M:&tbnh=88&tbnw=142&prev=/images%3Fq%3Dmoped%2Bgearbox%26um%3D1%26hl%3Den%26sa%3DN%26tbs%3Disch:1
        >
        > On Sun, Feb 28, 2010 at 2:05 PM, Rich <astronut1001@...> wrote:
        >
        > >
        > >
        > > Bernard;
        > >
        > > I find it difficult to picture a variable diameter pulley that will work
        > > with a cogged timing belt as used on some bicycles and motorcycles
        > > currently. They work fine for V belt power transmission as used on
        > > snowmobiles and in industry. V belts and timing belts are different critters
        > > however.
        > >
        > > Same problems as doing a variable diameter chain sprocket. They have been
        > > done in the past but they are complex, heavy and expensive to both make well
        > > and provide good reliability.
        > >
        > > Separately controlled variable diameter pulleys would require a quite
        > > strong belt tensioner of some sort. Typical V belt variable transnissions
        > > have one pulley controlled by a speed or RPM sensor and the other spring
        > > loaded to open and close as required to maintain correct belt tension.
        > >
        > > The derailleur system has survived due to being inexpensive to make, light
        > > weight and surprisingly efficient. It is also easy to understand and adjust
        > > or repair.
        > >
        > > Rich Wood
        > >
        > >
        > > --- In Geared_hub_bikes@yahoogroups.com<Geared_hub_bikes%40yahoogroups.com>,
        > > "bernard.morey" <bernard@> wrote:
        > > >
        > > >
        > > > --- In Geared_hub_bikes@yahoogroups.com<Geared_hub_bikes%40yahoogroups.com>,

        > > David Dannenberg <ddannenberg@> wrote:
        > > > >
        > > > > My experience is that chains are always filthy no matter what they are
        > > lubed with. That and rusty. If chains were superior, they would not have
        > > been replaced by belts in so many industrial applications. Obviously there
        > > are advantages and disadvantages to each. If a particular belt width and cog
        > > spacing becomes universal--as has chain size more or less--then I think we
        > > will see more and more of them, with many sizes available much like fan
        > > belts. True, the volume generated by the bicycle market is much smaller than
        > > the automotive market, but I still suspect that the belt could become
        > > ubiquitous. Match a belt with a Rohloff and a bb gearset like a Schlumpf and
        > > it seems to me you would have a clean durable very low maintenance set-up
        > > with as many gears as anyone could possibly want.
        > > > >
        > > > > David Dannenberg
        > > >
        > > > Quite so. A speculation: the next step will surely be a belt-based
        > > continuously variable transmission for bikes with variable pulleys at the
        > > front and rear controlled by individual twist controls.
        > > >
        > >
        > >
        > >
        >


      • anthonyeberger
        Oh Sure John, go ahead and jinx March for us midwesterners already. Now watch, because of you, we will have another month of cold winter riding ;) Thanks from
        Message 3 of 29 , Mar 1, 2010
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          Oh Sure John, go ahead and jinx March for us midwesterners already. Now watch, because of you, we will have another month of cold winter riding ;)

          Thanks from the riding guys up Nort'

          Tony B.
          Xtracycletony
          Milwaukee WI (which was about 22 degrees this morning)

          --- In Geared_hub_bikes@yahoogroups.com, John Werner <wernercj@...> wrote:
          >
          > There seems to be a lot of debate on here about the belt drive and most of it appears to be speculation since from what I can deduct very few if any have a belt drive.
          >
          > Since I have a belt drive I guess I can be the beta tester. I usually ride around 3,700 miles or 5,955 K a year. I put about 1,000 mi. on each single bike and about 700 on the tandem. I figure this season I will get about 1,000 mi. on the Soho. I will keep the group updated on how the belt drive is going once the heavy riding season starts and hopefully that time is almost here. March has got to be better than this month.
          >
          > John Werner
          > Maryville, IL
          > Easy Racers GRR, RANS Zenetik, Sun EZ-Tandem, Trek Soho
          >
          >
          >
          >
          > ________________________________
          > From: bernard.morey <bernard@...>
          > To: Geared_hub_bikes@yahoogroups.com
          > Sent: Sun, February 28, 2010 1:42:50 AM
          > Subject: [Geared_hub_bikes] Re: speculation on the future of belt drive
          >
          >
          >
          > --- In Geared_hub_bikes@ yahoogroups. com, David Dannenberg <ddannenberg@ ...> wrote:
          > >
          > > My experience is that chains are always filthy no matter what they are lubed with. That and rusty. If chains were superior, they would not have been replaced by belts in so many industrial applications. Obviously there are advantages and disadvantages to each. If a particular belt width and cog spacing becomes universal--as has chain size more or less--then I think we will see more and more of them, with many sizes available much like fan belts. True, the volume generated by the bicycle market is much smaller than the automotive market, but I still suspect that the belt could become ubiquitous. Match a belt with a Rohloff and a bb gearset like a Schlumpf and it seems to me you would have a clean durable very low maintenance set-up with as many gears as anyone could possibly want.
          > >
          > > David Dannenberg
          >
          > Quite so. A speculation: the next step will surely be a belt-based continuously variable transmission for bikes with variable pulleys at the front and rear controlled by individual twist controls.
          >
        • John Werner
          We will be headed up your way in June. Going to do a week long ride in Door County. I doubt that I take the Soho. Will probably use the RANS crank forward or
          Message 4 of 29 , Mar 1, 2010
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            We will be headed up your way in June. Going to do a week long ride in Door County. I doubt that I take the Soho. Will probably use the RANS crank forward or maybe the recumbent tandem. It has to be warmer by June, but I hear it can stay quite cool in DC.
             

            John Werner

            Maryville, IL

            Easy Racers GRR, RANS Zenetik,  Sun EZ-Tandem, Trek Soho




            From: anthonyeberger <anthonyeberger@...>
            To: Geared_hub_bikes@yahoogroups.com
            Sent: Mon, March 1, 2010 12:35:18 PM
            Subject: [Geared_hub_bikes] Re: speculation on the future of belt drive

             

            Oh Sure John, go ahead and jinx March for us midwesterners already. Now watch, because of you, we will have another month of cold winter riding ;)

            Thanks from the riding guys up Nort'

            Tony B.
            Xtracycletony
            Milwaukee WI (which was about 22 degrees this morning

          • Rich
            Joseph; An example would be the NuVinci hub. It is specified as able to accept up to 130NM of torque or about 96 pound feet. Lets examine this 96LbFt limit.
            Message 5 of 29 , Mar 1, 2010
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              Joseph;

              An example would be the NuVinci hub. It is specified as able to accept up to 130NM of torque or about 96 pound feet.

              Lets examine this 96LbFt limit. With 170 mm cranks (6.69") this is 172 pounds of force at the crank arms and then multiply it by 2 due to the NuVinci specified minimum input ratio which halves the torque actually seen by the hub so the actual force applied at the pedals would need to be 344 pounds, with the pedals horizontal, to match the Nuvinci specified input torque limit! That sounds pretty strong to me.

              A strong rider when out of the saddle and pulling down on the bars can generate effective weight on the crank arms considerably above his own body weight. That is a torque level in excess of that generated at the crankshaft by a 2 liter car engine at its torque peak. A bottom bracket gearset has to be able to withstand it repeatedly for years. A rear wheel gearbox such as an IGH is subjected to lower torque in direct relation to the input ratio used.

              A humans power output is more like a steam engine than a car engine. The car engine puts out maximum torque at higher RPM while the human, or steam engine, puts out maximum torque at very low RPM or cadence in comparison.

              Rich Wood


              --- In Geared_hub_bikes@yahoogroups.com, Joseph Shaul <spasticteapot@...> wrote:
              >
              > I'm surprised that the gearboxes are so heavy - I would think they would be
              > lighter.
              >
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