Wondering if anyone has any info on dual stacked rear sprockets?

Discussion in 'Motorized Bicycle General Discussion' started by BenchDweller, Jan 9, 2020.

  1. BenchDweller

    BenchDweller New Member

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    I am new and on my second build. I am installing a CDHpower hub clamp sprocket mount with a 40 tooth. However I notice the 40 too the sprocket also contains the bolt patter for the rag spoke moubts. My idea is to use the metal.spoke clamps from the rag mounts as spacers and bolt tho e 44 and 40 together to make a dual.range stack. The 40 tooth mounting both to the hub clamp mount. Like the old enduros. Swap over as conditions change
    I figure I can't be the first to attempt this so figure maybe I would ask why I don't find many videos trying it.
     
  2. LR Jerry

    LR Jerry Well-Known Member

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    This concept has been used on single speed and fixie bikes for some time now. Where the rider has to manually move the chain to change ratios. The only time something like that would be practical is if you rode in two large but different terrain areas. Such as one large area is basically flat and the other large area you ride in has hills. If your terrain changes regularly then it's better to be able to shift on the fly. Most riders who want to shift would rather mechanically do it with a shift kit on the fly than stop and manually shift ratios.
     
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  3. BenchDweller

    BenchDweller New Member

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    That's exactly it. One side of my city is pretty flat and open . The other is hilly and or heavy traffic. A little extra on the torque would be nice in that part of town, but the speed nice on the flat canal trails and paths .

    I had a few minibikes as a kid with this type of setup and it was pretty practical.
     
  4. BenchDweller

    BenchDweller New Member

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    Anyway, my idea is I can get through stop and go traffic and the few hills easier. Then let her cool down a bit while switching to the 40 tooth when I get to easier flat open areas.

    Just seeking opinions about it on chain alignment but I don't see a few milimeters being critical.
     
  5. LR Jerry

    LR Jerry Well-Known Member

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    You'll definitely have to use a spring loaded tensioner or at least an adjustable fixed tensioner.
     
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  6. bairdco

    bairdco a guy who makes cool bikes

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    Chain alignment is pretty crucial on these bikes. Adding the rubber half moons and another sprocket would be about 1/2" or so of deflection.

    If your chain stayed on, it would most likely eat up your sprockets, both engine and hub, and probably grind away at the engine sprocket cover.

    But im not telling you not to try it.
     
  7. Larry Trotter

    Larry Trotter Member

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    My experience is that much offset will cause you great grief. Also the amount of chain you will have to deal with between the two sprockets will be significant.
     
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  8. indian22

    indian22 Well-Known Member

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    I agree that perfectly straight chain lines are a basic requirement. No chain misalignment should be tolerated on motor powered bikes. Like Larry said, much grief will follow, though you might get away with it for awhile, ride it much and it will happen quicker. Many of the guys that gripe about lousy chain quality, breakage, wear, Chinese junk etc. won't admit that they've never dealt with alignment issues. Just said that ought to be good enough and started riding, but bairdco got it right:try it, you may break a law or two of physics and get away with it, and really like the way your bike performs.

    A caveat to this is the reality of multi speed pedal bikes getting away with some cross chaining while using a spring loaded tensioner, because of the very modest power input of even pro racers, compared to motor powered bikes and the very high sophistication of the derail system. This said the real world experience of motor bike shifter kits which take advantage of this multispeed bicycle tech to couple a motor to a multi-speed, typically 7 speed, cassette through a jack shaft and it works well through a Shimano or Avid designed drive that allows for the chain offset, but I've talked with owners who've ridden these for years and they report using the center three or four cogs exclusively, to avoid the problem of cross chaining trying to use the extreme low and high cogs of the system. They still break an occasional chain or simply throw the chain at odd times, just like on a pedal mountain bike. It's the same solution that multi speed pedal bikers came to decades ago...don't cross chain between the extreme ranges.

    So that's the con and the pro of making an offset work, they will if you're up to the challenge of matching what Shimano makes or just buy a shifter kit and a frame that it will work on. They'll still throw chains, break & wear; just not as often.

    Rick C.
     
  9. LR Jerry

    LR Jerry Well-Known Member

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    My bike uses a 1x7 drive system and shifts automatically. However with the Staton Inc shift kit it's a double freewheel system. It's also capable of installing 3 chainrings. I've built a manual shifter for a friend using the SI shift kit with 3 chainrings. I told them to use this shift pattern 1(1-3), 2(3-5), 3(5-7). The chainring are 28,36,44, I build a custom 7 speed freewheel of 34,28,24,21,18,15,13. Hill climbing 1(1-3); level ground cruising 2(3-5); level ground high speeds and down hill 3(5-7).

    For pedal only 3x7 drive systems with a 10t cross over triple crank the shift pattern works like this 1(1-4), 2(2-5), 3(4-7) for 12 non redundant ratios. If a gear is too easy or too hard to comfortably maintain a cadence of 70-90 it means you're in the wrong gear. This is where a bicycle computer with a cadence meter comes in handy.
     
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  10. indian22

    indian22 Well-Known Member

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    LR you, Tony and a few others have had some good write ups on these and you've shared the journey in a few threads. These are definitely advanced designs that along with shifter kits have worked with chain offset successfully and your Stanton gets around the legal issue of manual shifting as well. Pretty slick....and also advanced, but doable for those with a mechanical bent.

    Rick C.
     
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  11. LR Jerry

    LR Jerry Well-Known Member

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    I'm in total agreement about left side alignment. The easiest way I can think of doing this would be using a jack shaft with sprockets that line up with each wheel sprockets
     
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  12. BenchDweller

    BenchDweller New Member

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    Thank you all for the input. It is all very much appreciated.

    I'll update as soon as we have a warm week to test this out. From the responses this is going to end badly, but let's see how soon and exactly how. :D...


    For Science and stupidity
     
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