Old is new

My family bike, Xtravois, looks a little peculiar, but I’ve discovered recently that the frame design has some precedent in historical bikes, along with with the passenger-capable assisted longbike concept embodied in Xtracycles and my Stokemonkey product together.

At speeds above about 12 MPH, the biggest retarding force on a typical bicycle is wind resistance. Drafting other cyclists or more powerful vehicles is a good way to go faster, or to use less energy. Early in bicycling history, cyclists vying for speed records would draft tandem teams. Of course, this required a strong tandem team, and the better job they did at creating a wind break, the harder it was for them to keep ahead of the contestant. When suitable motors became available, some very interesting pace bikes came into being.

1894 human-petroleum hybrid pacing longbike. The fellow in back has become a passenger, upright to catch the wind, with the motor taking over the stoker role.

By 1910 the pedals had fallen away on some designs at least.

Xtravois-like frame structure
Notice the frame structures’ resemblance to my Xtravois design: an elongated mixte. Eventually the pacebikes became predominantly regular-wheelbase mopeds called Derny pacers.

So, one way to view an Xtracycle equipped with a Stokemonkey human-electric hybrid drive is as a revival of a historical pacebike design, bent to practical purpose: replacing car trips. The motors sure have gotten smaller!

stokemonkey prototype


7 thoughts on “Old is new”

  • Mauricio Babilonia
    Mauricio Babilonia July 10, 2005 at 2:34 pm

    Hi Todd,

    I was a little shocked to see my girls at the bottom of this post, what not having been asked for permission and all, but then I remembered that I’d posted it on a public forum, for one thing, and one with no means of contacting the poster at that.

    So not that it matters, but yes, you may use it… 8-)

    BTW, is that Instigator one of yours?

  • Todd

    Hi Mauricio -

    I did make a point of linking the image to the place I found it, and referencing the image directly rather than making a copy. I try to do this whenever I “pinch” an image. Yours is one of the few good pictures of an Xtracycle with a passenger!

    The Instigator is not mine, but that of a Stokemonkey prototype tester.

  • Mauricio Babilonia
    Mauricio Babilonia July 11, 2005 at 2:57 am

    Hey, thanks for the reply. I hadn’t noticed that it was linked–for some reason my cursor doesn’t change when I mouse over that image in my browser.

    Also, I’m a great admirer of the xtravois. Imitation being the highest form of flattery, you should notice that my passenger’s handlebar borrows from your design (though it may not be too apparent in this photo).

    I’m also curious how the xtravois’ lateral rigidity compares to that of an ordinary Free Radical-mountain bike combination? I find that mine is quite flexy. (This is also why I’d asked asked about the Instigator…)

  • Todd

    Lateral rigidity is great with Xtravois – that was, indeed, a major design goal. I can get out of the saddle and honk up a hill with an adult passenger without the rear end going all noodly. One nice thing about Stokemonkey is you almost never need to get out of the saddle; you can apply lots of power more smoothly, so you don’t induce the wobbles.

    Stiffness actually a bit overkill with Xtravois, as it’s pretty heavy and rides like an empty schoolbus when not heavily loaded.

    I haven’t ridden an Instigator/Xtracycle myself, but 2 people I’ve talked to who own them are very happy with the overall solid feel.

    Try resizing your browser window and notice the image dimensions change. I think this coding technique confuses some browsers.

  • Mauricio Babilonia
    Mauricio Babilonia July 11, 2005 at 2:06 pm

    I think improved lateral stiffness would be a good argument in favor of Xtracycle producing their own frameset. It seems as though they already have a prototype:

    (though I’m not sure exactly how the relationship between the two companies is structured.)

    Their response on their forums has been that they don’t want to make a wide variety of sizes, but I bet they would do very well with about 3–small, medium and large. It’s not as if a cargo bike needs to fit like a custom touring or racing bike.

    I’m guessing they’ve seen your design…any reaction?

  • Mauricio Babilonia
    Mauricio Babilonia July 11, 2005 at 2:09 pm

    Huh…not sure where that URL went. It referred to the Worldbike press release on the xaccess.org Web site.

  • Todd

    You have to include the http:// part of URLs; not all start with “www”.

    I disagree about a workbike not needing to fit as well as any other! I thought Xtracycle should make a integrated bike, too, and I floated my design as a candidate. Individual feedback was positive, but I guess the time wasn’t right. Takes a lot of capital to do a whole bike, and the cargo bike market in familiar parts of the world is, well, practically non-existent. Meanwhile, regular Xtracycles work awful good.

Leave a Reply