"Crank forward" bikes get mainstream press

Luke writes:

But when his arms brace the bars, he can apply a force greater than
that exerted by his weight alone to the pedal. The arms are applying
force and their effort is consuming calories, .i.e., expend

snip

Jobst is applying the physics definition of "work" which is different
from the biological experience of "work" which is based on the
perception of muscle tension and fatigue. The comparison is not
apples and apples.

In article
. com,
"Johnny Sunset aka Tom Sherman"
wrote:

aka Jobst Brandt wrote:

The previous comments above are not germane. Mr. Leurre got force,
work and power confused....

Mr. Brandt should remember that Mr. Leurre is a lawyer and not an
engineer and cut him some slack.

Or go over to fr.soc.politique and start talking bosh.

--
Michael Press

In article , Tim McNamara
wrote:

Luke writes:

But when his arms brace the bars, he can apply a force greater than
that exerted by his weight alone to the pedal. The arms are applying
force and their effort is consuming calories, .i.e., expend

snip

Jobst is applying the physics definition of "work" which is different
from the biological experience of "work" which is based on the
perception of muscle tension and fatigue. The comparison is not
apples and apples.

Yes, I see now. Rereading the thread, particularly David Damerell's
response to PeteCresswell, clarified matters. I was confusing the arm
force applied in a synchronous but extraneous effort with that of the
legs which is actually responsible for the work; the first is a
corollary of the work, the second performs it.

Luke

Dans le message de ,
a
réfléchi, et puis a déclaré :
Pete Cresswell writes:

The arms in contrast have the leverage of the hand-to-pedal
distance which is many times greater besides which the force is
relatively static, so no "work" is being performed.

Somebody clear up my mind on this:
---------------------------------------------------------------------
- A person is standing.

- They have a 15-pound dictionary in their right hand.

- They are holding the dictionary out at arm's length - stationary.
---------------------------------------------------------------------

Is any work being done?

No.

Force is a load applied at some locatioon. moving that force through
a distance, in line with the force, (pedal rotating) is work, the rate
at which work is accomplished is power. Effort is not a technical
term in this sense.

In simple units we have:

force : pounds
work: foot-pounds
power: foot-pounds/second

The man standing at the bar on one foot, the other up on the brass
rail is doing no work, he should not be out of breath and isn't
working up a sweat. Climbing stairs with the same load on one foot at
a time is essentially that force times the rise of the flight of
stairs. Power is a measure of how fast the work is accomplished.

Hence, the bicyclist climbing a grade while standing is doing no
significant work with his arms although he is exerting static force
during each downstroke of the pedal. At the end of each pedal stroke
the bicycle is leaned to the other side under practically no load and
repeated for the other foot.

Jobst Brandt

and then later, where attributions were not exactly right :

You must be unfamiliar with no-hands riding -- you steer by
shifting your hips to tilt the bike, something that's not possible
from a standing position.

I think you're right, of course. But stabilizing, according the
the Prophet (of RBT) does not involve force. Go figure ...

It does not involve force that's significant in terms of forward
propulsion of the bike.

The previous comments above are not germane. Mr. Leurre got force,
work and power confused. Nowhere did I say that there is no force
exerted on the handlebar. Besides, the definitions were addressed in
other responses to this thread.

Jobst Brandt

Force through distance - OK - got it.
Pedal moves through a half circle of diameter35cm - work done, if I
understand you correctly.
BUT, in a hard effort climb en danseuse or in a sprint, bar at hand moves
left to right (for me, and I just made a measurement that seems
approximately suitable) 45cm. And that is not work ?

No one will question that there is less muscle mass and less force applied,
but so long as the flexible, complex organism is free of attachment or
anchor over the length from hand to foot, it seems hard to imagine that
there is no "work" done by hands, arms, back in the course of such riding.

--
Bonne route !

Sandy
Verneuil-sur-Seine FR

PS : there is no "Mr Leurre". It was pointed out just a couple of days ago,
that e-mail and names are not identical. Not that it's a valid e-mail, of
course. That would be too easy.

Luke writes:

In article , Tim McNamara
wrote:

Luke writes:

But when his arms brace the bars, he can apply a force greater
than that exerted by his weight alone to the pedal. The arms are
applying force and their effort is consuming calories, .i.e.,
expend

snip

Jobst is applying the physics definition of "work" which is
different from the biological experience of "work" which is based
on the perception of muscle tension and fatigue. The comparison is
not apples and apples.

Yes, I see now. Rereading the thread, particularly David Damerell's
response to PeteCresswell, clarified matters. I was confusing the
arm force applied in a synchronous but extraneous effort with that
of the legs which is actually responsible for the work; the first is
a corollary of the work, the second performs it.

I remember back in physics class when we discussed "work," I remember
it not making much sense initially because many things that don't
qualify as "work" in the physics sense were still hard work!

Johnny Sunset aka Tom Sherman wrote:
And your experience applies to the other 6 billion people on this
planet?

That's my goal. World domination.

Tom Sherman writes:

The previous comments above are not germane. Mr. Leurre got force,
work and power confused...

Mr. Brandt should remember that Mr. Leurre is a lawyer and not an
engineer and cut him some slack.

Slack, my eye. With the smart ass tone of his posts, no slack is due.
Expounding with snide innuendo on things he doesn't understand is not
a reasonable contribution to the discussion of bicycle propulsion.

Jobst Brandt

In article , Tim McNamara
wrote:

I remember back in physics class when we discussed "work," I remember
it not making much sense initially because many things that don't
qualify as "work" in the physics sense were still hard work!

;-) Yeah, I know. An expansion of that theme sums up most of my
scholastic endeavours: Much effort but little work to show for it!

Luke

Dans le message de ,
a
réfléchi, et puis a déclaré :
Tom Sherman writes:

The previous comments above are not germane. Mr. Leurre got force,
work and power confused...

Mr. Brandt should remember that Mr. Leurre is a lawyer and not an
engineer and cut him some slack.

Slack, my eye. With the smart ass tone of his posts, no slack is due.
Expounding with snide innuendo on things he doesn't understand is not
a reasonable contribution to the discussion of bicycle propulsion.

Jobst Brandt

I wonder if you and everyone else has noticed, that I don't shy away from
confronting your inaccuracies, misrepresentations, and gusts of
insubstantial proclamations, and yet you are not able to refute the very
simply put statements I challenge you with. As here, you hide behind a
screen, attempting to discredit with an empty proposition. You imagined I
would not drag it on.

One thing the practice of law does is encourage persistence. Persistence in
grasping the underlying reality, and in discarding bluff and appreciating
transparency. I have litigated numerous cycling related matters, and the
real experts - those who can help non-engineers to understand the matter at
hand - are up to date, can communicate complex ideas, and don't scoff at
ideas that don't line up with their theories. They are able to create a
harmony of thought. They don't attack innocent questions or questioners as
though there was no right to ask. They are patient with those who need
concrete examples. And, whether they were my experts or for the opposition,
they were exceptionally credible for all these traits.

You were probably pretty good, once. Time to update your CV. Perhaps to
retire it.
--
Bonne route ! (Is this your favorite ?)

Sandy
Verneuil-sur-Seine FR

In article , Sandy
wrote:

Dans le message de ,
a
réfléchi, et puis a déclaré :
Tom Sherman writes:

The previous comments above are not germane. Mr. Leurre got force,
work and power confused...

Mr. Brandt should remember that Mr. Leurre is a lawyer and not an
engineer and cut him some slack.

Slack, my eye. With the smart ass tone of his posts, no slack is due.
Expounding with snide innuendo on things he doesn't understand is not
a reasonable contribution to the discussion of bicycle propulsion.

Jobst Brandt

I wonder if you and everyone else has noticed, that I don't shy away from
confronting your inaccuracies, misrepresentations, and gusts of
insubstantial proclamations, and yet you are not able to refute the very
simply put statements I challenge you with. As here, you hide behind a
screen, attempting to discredit with an empty proposition. You imagined I
would not drag it on.

One thing the practice of law does is encourage persistence.

snip

It seems also to encourage a tendency toward long-winded, self-serving
digressions. Case adjourned.

Luke