A bicycle built for… Siamese twins?

This project really puts an end to arguing over who has to ride in the back of the tandem bicycle. We challenge you not to smile while viewing the maiden voyage that [Carlos] and his daughter take on this side-by-side bicycle. The video can be found after the break.

It certainly makes a bit more sense than an over-under tandem, and the fabrication process is really quite manageable. This requires alterations to the seat, handle bars, and pedals, but the majority of the bike (frame, gearing, fork, wheels) is unaltered.

The cranks have been replaced by a custom welded cam mechanism that reminds us of how the pedals on a paddle boat work. Both riders must pedal at the same time and rate. To give each a place to sit the seat post was converted into a T bar to host saddles to the right and left of the frame. Finally, the handle bars are the most complicated of all. Extra framing was welded onto both sides for the front tube to provide a place to mount two pair of handle bars. One of them is fixed in place, the other can be turned, using a lever mechanism to steer the front fork.

It looks a bit awkward to get started, but once both riders are up it seems quite stable.

24 thoughts on “A bicycle built for… Siamese twins?

  1. while this isn’t exactly a new idea (you can find the design as far back as around 1896) it’s still cool to see it done with modern materials. The only real downside I can see is that you can’t easily ride it with just one person like you can with a regular tandem bicycle.

    1. Easy is relative, and there’s a learning curve no doubt, but a video at the instructable shows the bike is practical for one person to ride.

  2. I thought siameese twins have to be identifcal.
    if they want babies watching your brother get it on with a chick while you do is fine. but watching your sister? ew!

  3. Geee,,, the last two comments are so negative and lame… Probably from Siamese jerks!

    Guys, don’t you see that this is about building something?! Go out and build something rather than criticizing! How many of you have already built something and have it published anywhere? I do. And in several magazines and websites, so I have the right to speak.

    I think it is a great built and kudos for the author and for doing it!

    1. I agree, it is a great build. The original concept was for the riders to more easily talk to each other and enjoy each others company. Like I said above the earliest concept for this starts around 1890’s, and as you can imagine going anywhere with ‘your girl’ other than across the street could be a challenge before cars, unless you owned an Oat Guzzler. This provided a nice alternative.

      Oh, and my earlier comment about the ease of use by one rider wasn’t intended as a criticism but a simpler observation.

    2. Wow, you had a good point. I really hope you didn’t mean this last part in the terrible tone it sounded though:

      >”How many of you have already built something and have it published anywhere? I do. And in several magazines and websites, so I have the right to speak.”

      It is fine to criticize negativity, but the fact that you have built something that has been published in no gives you more of a right to speak than anyone else.

      Your criticism was sound; your reasoning was absurd.

  4. Think about it, a bike that is very useless with only one person. I bet she built it with him every step of the way, so they could ride it together! This is seeping with soo much joy & quality bonding, that it could be made out of claydough and toothpicks and it would still have my props. Way to go dad!

    I would seriously like to see you trolls not go to walmart if you were in the same predicament.

    1. There’s no reason that one person can’t pedal this bike. It just has to lean to one side.

      If the pedals on either side were antisymmetric, then it would be possible to pedal from the centre by sliding one seat to the middle.

  5. I can imagine the bottom bracket holding up very long. I would hate to riding when it fatigued and broke. Let one the wheel bearings. Your are over doubling the weight. That also means no more lane splitting in traffic.

  6. Years back, I saw a couple riding one of these tandmoms. Two things that I found interesting.

    1 – The man riding weighed 2x what the woman did, so the seat assembly was shifted towards her side, to balance them out (think seesaw.

    2 – Steering the bike meant one person pulled the steering assembly while the other pulled. I’m sure that took a little getting used to.

  7. fyi, I saw similar side-by-side bicycles in use as summer rentals in a few of the GWN ski areas way back in the mid-80’s. Back then they’d been available as rentals for years, and as already pointed out, the idea’s not new. It may be nicely done, there is one very obvious improvement that the builder hasn’t arrived at yet…

    The bike designers in B.C. were bright enough to attach the seat-mounts via a bracketed lateral tube, which could be slid sideways a few inches to compensate(up to a point)for differing weights in each saddle.

    I’d be far more impressed if someone can devise a way to make cagers pay attention to those of us who are on two wheels.

    Like a bike-portable Death-Ray. :)

  8. This looks like a bicycle from the Dutch TV show called
    on land and sea air in this proramma you in a homemade vehicle down a track as soon as you can to the bell and ring it

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