Unusual Tandem Bicycle

I saw this unusual tandem bicycle in Santa Cruz last week. I’m trying to figure out some of the weird features of this tandem.

Weird tandem

For example,

  • How does that big ring inside the timing chain stay in place?

  • What is that extra set of cranks under the stokers bars for? Russ suggests these might be hand cranks, but I think they might allow a very short rider to pedal recumbent style.
  • What about that handle that appears to stick out obliquely from the stoker’s saddle? Another hint that this might be for a short rider?

Your thoughts?

16 Comments

  • greg
    August 24, 2009 - 5:39 pm | Permalink

    With enough tension, the chain can hold the big ring in place by itself. He's probably using the ring as a DIY chain tensioner. doesn't seem particularly stable, though – either an impact or a jam at either end of the chain would be enough to dislodge it.

  • greg
    August 24, 2009 - 10:39 am | Permalink

    With enough tension, the chain can hold the big ring in place by itself. He's probably using the ring as a DIY chain tensioner. doesn't seem particularly stable, though – either an impact or a jam at either end of the chain would be enough to dislodge it.

  • Wayne
    August 24, 2009 - 6:27 pm | Permalink

    +1 for chain tensioner. Without it, the chain was probably 1/2 a link too long.I also think the second crankset is for the recumbent position and the handle at the rear is for the same.

  • Wayne
    August 24, 2009 - 11:27 am | Permalink

    +1 for chain tensioner. Without it, the chain was probably 1/2 a link too long.

    I also think the second crankset is for the recumbent position and the handle at the rear is for the same.

  • jasper9
    August 24, 2009 - 7:42 pm | Permalink

    is that a motor in the rear hub and possibly batteries in the bag?

  • jasper9
    August 24, 2009 - 12:42 pm | Permalink

    is that a motor in the rear hub and possibly batteries in the bag?

  • Cliff
    August 24, 2009 - 7:50 pm | Permalink

    I think the post from the stokers seat and the cranks under the bars are for a child, the child seat clips to the bar from under the stoker and the Kid gets to peddle, to.

  • Cliff
    August 24, 2009 - 12:50 pm | Permalink

    I think the post from the stokers seat and the cranks under the bars are for a child, the child seat clips to the bar from under the stoker and the Kid gets to peddle, to.

  • Yokota Fritz
    August 24, 2009 - 7:52 pm | Permalink

    Jasper, that looks almost like a hub motor but that's an Arai drum brake.Cliff — Aha! I thought of that bar as a handle for the child but your idea makes better sense.

  • Yokota Fritz
    August 24, 2009 - 12:52 pm | Permalink

    Jasper, that looks almost like a hub motor but that's an Arai drum brake.

    Cliff — Aha! I thought of that bar as a handle for the child but your idea makes better sense.

  • JH
    August 25, 2009 - 1:43 am | Permalink

    Bet that free-floating tensioner pops out all the time when you hit an inconvenient bump. Either that, or he's just messing with us.

  • JH
    August 24, 2009 - 6:43 pm | Permalink

    Bet that free-floating tensioner pops out all the time when you hit an inconvenient bump. Either that, or he's just messing with us.

  • greenobike
    August 25, 2009 - 3:32 am | Permalink

    Apparently it's called a "ghost" or "phantom" chainring.http://www.mtbr.com/ssfaqcrx.aspx#ssCompTensioners

  • greenobike
    August 24, 2009 - 8:32 pm | Permalink

    Apparently it's called a "ghost" or "phantom" chainring.

    http://www.mtbr.com/ssfaqcrx.aspx#ssCompTensioners

  • Grey
    August 25, 2009 - 2:49 pm | Permalink

    That's really interesting and I've nver seen that before!

  • Grey
    August 25, 2009 - 7:49 am | Permalink

    That's really interesting and I've nver seen that before!

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