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Dwell, the Trailcart, and a challenge

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I like to mention bike content in general design magazines when I see it, so I want to point you to a Dwell blog post about handmade bicycles. The post dates back to February, but it was new to me when I discovered it today, so I assume some of you missed it as well. The rear dropout shown here from a Vanilla road bike is just one of the detail shots you will see in the post.

The Trailcart has been spreading around the web since it appeared on Treehugger and Gizmodo. This pedal powered vehicle with independent four-wheel drive was designed by hobbyist Frank Fraune of Germany. The machine, which uses a Shimano Nexus 8 speed transmission, has up to 400mm of axle displacement. After looking at the pictures on the Treehugger post and in the Trailcart Gallery, all I can say is that I would love to try this thing out. If I did get a chance to ride it though, I would probably leave my team kit in the closet.

Ari of the Bits and Bikes blog has a question/challenge for all you designers and engineers who might be reading: Can you build a fixed-effort bicycle? The idea, which he is calling “NuFixie”, is to build up a bike that uses the NuVinci CVP hub, while controlling the gear ratio automatically based on sensor input measuring chain tension. He is looking for feedback, so leave a comment here or at his post if you have anything to say about his idea or about any other constant effort bicycle transmission concept. His post makes me want to go back and review the discussion of nonpositive drives and variable automatic transmissions in “Bicycling Science”. That book is always a great source on such subjects, but it worth keeping in mind that quite a bit has happened since the 80s. Some ideas that were not really practical at the time may become more feasible as new technologies emerge. In other words, don’t rule an idea out just because of obstacles in past attempts to make it work.

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  1. Sean June 3, 2008 at 2:51 pm -  Reply

    Speaking of ideas not practical at the time and Bicycling Science, there’s a great ABS braking system in that book from the 70s where fork strength was the limiting factor. I think it wouldn’t take much to make it work these days.

  2. Lazy Bike Commuter June 3, 2008 at 3:26 pm -  Reply

    I think the Trailcart would be awesome for commuting in snow.

  3. jimmythefly June 3, 2008 at 5:16 pm -  Reply

    Seems that for a fixed effort bike, hemight consider linking the transmission to a heart-rate monitor, too.

  4. Ron June 4, 2008 at 12:16 am -  Reply

    James : Thanks for the link to challenge. Here is my idea.

    Sean : If you’re talking about the book bicycling science, I have not read anything about ABS. Care to point out?

  5. bikesgonewild June 4, 2008 at 5:37 am -  Reply

    …the trailcart looks pretty cool although the cg seems incredibly high…my old friend john davis used to run his wheelchair cart in races including the mammoth mountain DH & as i recall, john’s cart not only had independent suspension but a much lower cg…the chain drive train precludes that on the ‘trailcart’ but i wonder how that might be circumvented…

    …re: practical ideas/ emerging technologies…
    …i remember mert lawell, he of harley davidson “grand national championship” fame telling me that when he was researching patent rights on his various mtb suspension ideas, which he licensed to various companies, that he discovered volumes of ideas from the late 1800’s that were never considered practical in their day due to weight & susceptibility of then ‘state of the art’ materials…

    …quick historical note about mert lawell…mert designed his own rear suspension for his flat tracker harley when he raced grand national events…guys laughed, told him he was crazy…mert won the #1 plate that year & championship flat trackers have run rear suspension since…

    …sometimes it is the timing & availability of materials that makes the difference…

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