The Dancing Chain, by Frank Berto

Jeff Starr wrote:

And I disagree with you, so? it might be helpful if you explained
what/why you disagree with the above.

Some people like to figure things out for themselves and all they need is
a pointer in the right direction. I suspect that Sheldon falls into that
category.

It makes sense to me.

Do some research on this topic area and see if it still makes sense.

--
Still a proud member of the reality-based community.

Jeff Starr wrote:

On Tue, 7 Dec 2004 10:36:30 +0100, "Robert Chung"
wrote:
Hmmm. Within that same page, I disagree with much of the stuff you've
written in this topic:
http://sheldonbrown.com/gear-theory.html#cadence, but particularly with
this:

"For the cyclist who wants to maximize efficiency, there is a particular
combination of cadence and resistance that will produce the most power
with the least stress on the body. [...] The idea of gears is to select
the gear in which this combination of cadence and resistance is met.
Depending on the wind, grade and surface conditions, your speed may be
faster or slower, but theoretically your legs should always be pushing
against the same resistance, and spinning the cranks at the same cadence."


And I disagree with you, so? it might be helpful if you explained
what/why you disagree with the above.
It makes sense to me.

Robert won't bother to give you the answer, but you can read the results
of his research at http://mywebpage.netscape.com/rechung/wattage/. In a
nutshell, his research shows that the rider optimizes torque more than
cadence.

--
Dave
dvt at psu dot edu

Sheldon Brown wrote:

Quoth Frank Krygowski:

The key is that on a log plot, equal percent changes show up as equal
distances between points.

If you felt that each gear change should have the same effect (say,
reducing your gear ratio by 5%) then you could plot different cog
combinations until you achieved equal spacing on a log plot. If you
felt you wanted greater spacing in the low gears and finer spacing in
the high gears, you could verify that as well.

If you plotted things on a linear scale, or just looked at the number
of gear inches, you might think shifting from a 100 inch gear to a 95
inch gear would feel the same as shifting from a 30 inch to a 25
inch. But in practice, the former is a fine adjustment, the latter is
a pretty big jump.


That would be true if we cycled in a vacuum, opposed by linear
frictional resistances only.

However, the non-linearity of air resistance cancels this out to a
considerable extent.

See: http://sheldonbrown.com/gear-theory.html#progression

I don't see your logic, Sheldon. As I'm sure you've mentioned in the
past, changing gears is a matter of impedance matching. The load
linearity doesn't have any bearing on impedance matching. If you go 10%
faster and you want to shift up a gear to compensate, it doesn't matter
if the load is dominated by gravity (up a hill) or wind resistance (on
the flats).

I do see your point about minimizing the number of shifts on uphills to
minimize the loss of momentum, but with the advent of hyperglide tooth
shaping, barely any momentum is lost.

I think gears should be spaced roughly the same top - bottom. And I
mean that they should be changed exponentially (% change kept constant),
not linearly (i.e. 5 inch jumps).

--
Dave
dvt at psu dot edu

--
Dave
dvt at psu dot edu

dvt writes:

Robert won't bother to give you the answer, but you can read the
results of his research at
http://mywebpage.netscape.com/rechung/wattage/. In a nutshell, his
research shows that the rider optimizes torque more than cadence.

That webpage is exactly the sort of thing the word "pseudoscience"
describes perfectly. Some of the conclusions presented may in fact be
correct, but to present them in that format, as if they had been
proven, is laughable.

dvt wrote:
Robert won't bother to give you the answer, but you can read the results
of his research at http://mywebpage.netscape.com/rechung/wattage/. In a
nutshell, his research shows that the rider optimizes torque more than
cadence.

Not exactly. My intention wasn't to say that riders optimize torque and
not cadence; it was to show that cadence and torque usually (but not
always) are jointly chosen. It's true that I believe that efficiency isn't
usually something we naturally seek to optimize, but that particular
webpage doesn't address that issue since I was focusing only on power
meter data and power meters don't measure efficiency.

Jim Smith wrote:

That webpage is exactly the sort of thing the word "pseudoscience"
describes perfectly. Some of the conclusions presented may in fact be
correct, but to present them in that format, as if they had been
proven, is laughable.

I include URLs for all the data files. When you've finished your analysis
and write-up, I'll link to it.

--
Still a proud member of the reality-based community.

Robert Chung wrote:

dvt wrote:
Robert won't bother to give you the answer, but you can read the results
of his research at http://mywebpage.netscape.com/rechung/wattage/. In a
nutshell, his research shows that the rider optimizes torque more than
cadence.

Not exactly. My intention wasn't to say that riders optimize torque and
not cadence; it was to show that cadence and torque usually (but not
always) are jointly chosen. It's true that I believe that efficiency isn't
usually something we naturally seek to optimize, but that particular
webpage doesn't address that issue since I was focusing only on power
meter data and power meters don't measure efficiency.

What definition of efficiency are you using?

gwhite wrote:
Robert Chung wrote:

It's true that I believe that efficiency
isn't usually something we naturally seek to optimize, but that
particular webpage doesn't address that issue since I was focusing
only on power meter data and power meters don't measure efficiency.

What definition of efficiency are you using?

Power meters measure power output, not any input, so whichever definition
of efficiency you use (gross, net, delta, or work efficiency) a power
meter won't tell you what you need to know in order to calculate it.

(From http://www.bsn.com/Cycling/articles/cadence.html:
"1 ) gross efficiency, the ratio of the work accomplished to energy
expended, that is, the effectiveness of converting chemical energy into
mechanical work; 2) net efficiency, the ratio of the work accomplished to
the energy expended above that during rest, that is, the cost of resting
metabolism is subtracted from the denominator in the computation; 3) work
efficiency, the ratio of the work accomplished to the energy expended
above that during cycling with no load, calculated by subtracting from the
denominator the cost of moving the legs plus the resting metabolism, and
4) delta efficiency - the ratio of the change in the power output to the
change in the energy expended at each power output."


--
Still a proud member of the reality-based community.

On Tue, 7 Dec 2004 10:36:30 +0100, "Robert Chung" wrote:

Sheldon Brown wrote:

See: http://sheldonbrown.com/gear-theory.html#progression

Hmmm. Within that same page, I disagree with much of the stuff you've
written in this topic:
http://sheldonbrown.com/gear-theory.html#cadence, but particularly with
this:

"For the cyclist who wants to maximize efficiency, there is a particular
combination of cadence and resistance that will produce the most power
with the least stress on the body. [...] The idea of gears is to select
the gear in which this combination of cadence and resistance is met.
Depending on the wind, grade and surface conditions, your speed may be
faster or slower, but theoretically your legs should always be pushing
against the same resistance, and spinning the cranks at the same cadence."

I was going to ask what in there you disagreed with. Then I read your replies to
others who had the same question and discovered that I really don't give a ****
what you think.

Thanks.

Ron.

RonSonic wrote:
I was going to ask what in there you disagreed with. Then I read your
replies to others who had the same question and discovered that I
really don't give a **** what you think.

You had to read my replies before you came to that conclusion? You must be
new around here. Most of the regulars figured that out long ago. Ask
g-spot.