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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