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Summer science quiz #4

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  • Summer science quiz #4

    Dear all,

    I was out cycling around the vineyards of Virginia this Memorial Day
    weekend, and since we were in the vicinity of Old Rag Mountain, we had
    to dismount several times to cope with the hills. My question for you
    this week, therefore, is:

    What combination of grade of slope and gear ratio (and perhaps other,
    specified, physiological/biomechanical factors) will prompt a cyclist to

    Of course, I know that cyclists come in a range of fitnesses (especially
    if taking part in a winery tour!). However, it seems to me that we ought
    to be able to come up with a rough prediction of the criteria which
    would typically make a person change from cycling to walking. As a
    start, I wondered, for example, what gear ratio (in gear-inches or
    whatever) on a bike is equivalent to walking? Would it be possible to
    make a bicycle that would be as comfortable to ride up a steep incline
    as it would be to walk up it? If so, what gear ratio would this cycle
    need to have for, say, a 30 degree slope?

    I look forward to your replies...

    Dr. Chris Kirtley MD PhD
    Associate Professor
    HomeCare Technologies for the 21st Century (Whitaker Foundation)
    NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation
    Dept. of Biomedical Engineering, Pangborn 105B
    Catholic University of America
    620 Michigan Ave NE
    Washington, DC 20064
    Tel. 202-319-6247, fax 202-319-4287

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