Bike aerodynamics / weight

[[email protected]]

Tim McNamara writes:

>> Although the man standing at the bar on one leg is not doing work,
>> he is using a bit of energy to hold the pose. I think some birds
>> can properly lock out their knees, but people need to burn a bit of
>> fuel continuously just to stand still.

> Work in the mechanical sense and work in the biological sense have
> different connotations. Humans can work very hard to not move, from
> the biological sense of the term.

Oh ****, here we go again. WORK = FORCE x DISTANCE

The subject is mechanical work in propelling bicycles. The man
standing on one leg at the bar with the other foot on the brass rail
is NOT doing work.

You are mixing muscle contraction with work. Holding your arm out
horizontally can become painful but it is not WORK.

Jobst Brandt

 

[Ben C]

On 2007-01-16, [email protected] <[email protected]> wrote:
> Ben C? writes:
[snip]
>> Google quickly found this short movie clip of the Tour finish in
> Paris:
>
> http://video.cyclingnews.com/road/2006/tour06/video/tour0620.wmv
>
>> If you go right to the end of the clip, there's a good head-on shot
>> of the sprint finish. If you can slow down your movie player (I ran
>> it at 1/10th speed using mplayer with the option -speed 0.1) you can
>> clearly see that most if not all of the riders at the front are
>> pulling the bike up to vertical while pushing down with the opposing
>> leg.
>
> As I said, ride bike and try it yourself.

I have, and it does feel as I pull the bike from side to side that I'm
pulling against something-- more than just the force required to tip the
bike.

> You are not performing any significant work with the arms.

I doubt it's significant in my case, yes.

> Were that the case, professional bicyclists would develop great biceps
> and other muscles in the arms, which they do not.

Well, it's not so black-and-white as that, they also have to keep their
weight down, and if the arms are only slightly useful, you'd expect the
biceps etc. to be only slightly larger than normal, and only then for
the sprinters.

> This subject comes up often in this forum. You might search old
> editions.

I remember discussing this before, yes. All I was saying was that I
think sprinters are doing _some_ work with their arms, and I think that
point has been clarified. I wasn't making claims about whether it was
significant or necessary (although I keep an open mind).

 

[John Forrest Tomlinson]

On 16 Jan 2007 23:10:08 GMT, [email protected] wrote:

>Ben C? writes:
The ? is so tiresome. If he wrote Ben Clifford would it make his
comments less valid?
--
JT
****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

 

[[email protected]]

Ben C? writes:

> [snip]

>>> Google quickly found this short movie clip of the Tour finish in
>>Paris:

>> http://video.cyclingnews.com/road/2006/tour06/video/tour0620.wmv

>>> If you go right to the end of the clip, there's a good head-on
>>> shot of the sprint finish. If you can slow down your movie player
>>> (I ran it at 1/10th speed using mplayer with the option -speed
>>> 0.1) you can clearly see that most if not all of the riders at the
>>> front are pulling the bike up to vertical while pushing down with
>>> the opposing leg.

>> As I said, ride bike and try it yourself.

> I have, and it does feel as I pull the bike from side to side that
> I'm pulling against something-- more than just the force required to
> tip the bike.

>> You are not performing any significant work with the arms.

> I doubt it's significant in my case, yes.

Not that, I mean as part of propelling your bicycle. There is no
force times distance. Consider the angle and length change of
shoulder to hand and the force required to accomplish that. There
isn't much motion and it is an insignificant force compared to the leg
force and its stroke.

>> Were that the case, professional bicyclists would develop great
>> biceps and other muscles in the arms, which they do not.

> Well, it's not so black-and-white as that, they also have to keep
> their weight down, and if the arms are only slightly useful, you'd
> expect the biceps etc. to be only slightly larger than normal, and
> only then for the sprinters.

It isn't a matter of whether they want to develop muscular bulk or
not. If those muscles are working in the manner in which it is
perceived, the muscles would grow just as bicyclists leg muscles do.
If there is no work taking place there the muscles remain as they are.

>> This subject comes up often in this forum. You might search old
>> editions.

> I remember discussing this before, yes. All I was saying was that I
> think sprinters are doing _some_ work with their arms, and I think
> that point has been clarified. I wasn't making claims about whether
> it was significant or necessary (although I keep an open mind).

If you are climbing a long grade, I think you'll find that changing
from sitting to standing is a matter of relaxing one set of (back)
muscles and using others, it does not increase or decrease speed. The
speed is governed by aerobic capacity. This is assuming you have the
facility to ride naturally in either position. There are plenty of
riders who cannot ride standing on a grade.

Jobst Brandt

 

[Tim McNamara]

In article <[email protected]>,
[email protected] wrote:

> Tim McNamara writes:
>
> >> Although the man standing at the bar on one leg is not doing work,
> >> he is using a bit of energy to hold the pose. I think some birds
> >> can properly lock out their knees, but people need to burn a bit of
> >> fuel continuously just to stand still.
>
> > Work in the mechanical sense and work in the biological sense have
> > different connotations. Humans can work very hard to not move, from
> > the biological sense of the term.
>
> Oh ****, here we go again. WORK = FORCE x DISTANCE

I know the definition of work in the mechanical sense. We covered it in
junior high school science class and it comes up here regularly just to
reinforce it.

I also know the definition of work in the human sense. Normal people
who don't read wreck.bikes will tell you it's damned hard work to hold a
couple of cement blocks in their arms for a half an hour. People will
refer to algebra as hard work, too, even though it involves no moving
parts. It boils down to:

Work = subjective effort

in the normal sense of the word "work." People live in the world of
muscular contraction, not in the world of equations. Equations describe
how the world acts, they do not govern how the world acts and they do
not define human perception. Map != territory. It's too bad that the
formulation of W = F * D uses the word "work" in a way which is oblique
to normal human experience. It muddles the conversation.

You can holler all you want about it, but if you don't accommodate
yourself to normal usage of language in these discussions you will be
hunting unicorns and accomplishing little. It's best to pick your
battles.

> The subject is mechanical work in propelling bicycles. The man
> standing on one leg at the bar with the other foot on the brass rail
> is NOT doing work.
>
> You are mixing muscle contraction with work. Holding your arm out
> horizontally can become painful but it is not WORK.

That was my point. Not only can muscular contraction become painful but
can increase heart and respiration rate, consume glucose for energy and
release waste heat and carbon dioxide- even while standing motionless.
Normal people, using normal definitions, will refer to that as work.
*You* might not, because you're thinking about it as an engineer, but
99%+ of the world population will not be using the mechanical definition
of work. They'll be thinking "riding up that hill was hard work."
Riding a bike is involves muscular contraction. When you're talking
about riding a bike, work as subjective effort is going to get dragged
into the discussion. You're not talking with engineers.

You might as well relax about it. It's come up before, it will come up
again. The guy who wrote W = F * D would have done us a better service
by choosing a different term on the left side of the equation. One that
didn't already have a vernacular working definition that can be at odds.

 

[[email protected]]

Tim McNamara writes:

>>> Work in the mechanical sense and work in the biological sense have
>>> different connotations. Humans can work very hard to not move,
>>> from the biological sense of the term.

>> Oh ****, here we go again. WORK = FORCE x DISTANCE

> I know the definition of work in the mechanical sense. We covered
> it in junior high school science class and it comes up here
> regularly just to reinforce it.

> I also know the definition of work in the human sense. Normal
> people who don't read wreck.bikes will tell you it's damned hard
> work to hold a couple of cement blocks in their arms for a half an
> hour. People will refer to algebra as hard work, too, even though
> it involves no moving parts. It boils down to:

> Work = subjective effort

> in the normal sense of the word "work." People live in the world of
> muscular contraction, not in the world of equations. Equations
> describe how the world acts, they do not govern how the world acts
> and they do not define human perception. Map != territory. It's
> too bad that the formulation of W = F * D uses the word "work" in a
> way which is oblique to normal human experience. It muddles the
> conversation.

Lats time I noticed this was "rec.bicycles.tech" in which we discuss
technical subjects, it is not "rec.bicycles.psychology". Therefore,
this is a classic red herring that we see here on almost any clearly
defined technical subject.

http://www.m-w.com/dictionary/red herring

> You can holler all you want about it, but if you don't accommodate
> yourself to normal usage of language in these discussions you will
> be hunting unicorns and accomplishing little. It's best to pick
> your battles.

Thanks for picking your own battle. I think you are the intruder, the
subject being clearly defined at the outset.

>> The subject is mechanical work in propelling bicycles. The man
>> standing on one leg at the bar with the other foot on the brass
>> rail is NOT doing work.

>> You are mixing muscle contraction with work. Holding your arm out
>> horizontally can become painful but it is not WORK.

> That was my point.

Jobst Brandt

 

[Bill Sornson]

[email protected] wrote:

> Lats time I noticed this was "rec.bicycles.tech" in which we discuss
> technical subjects...

This from a guy who posts (cuts and pastes) political stuff on here fairly
regularly, and who once demeaned a person for putting a RIDE REPORT in
rec.bicycles.miscellaneous because it "belonged" in rb-rides.

Same guy gives people grief about typos, yet his prolific spellchecker
missed "Lats".

Same guy criticizes posters' user names, yet refuses to fix his. (An e-mail
address is not the same as a user name.)

Bill "fertile grounds" S.

 

[Ben C]

On 2007-01-17, [email protected] <[email protected]> wrote:
> Ben C? writes:
[snip]
>> Well, it's not so black-and-white as that, they also have to keep
>> their weight down, and if the arms are only slightly useful, you'd
>> expect the biceps etc. to be only slightly larger than normal, and
>> only then for the sprinters.
>
> It isn't a matter of whether they want to develop muscular bulk or
> not. If those muscles are working in the manner in which it is
> perceived, the muscles would grow just as bicyclists leg muscles do.
> If there is no work taking place there the muscles remain as they are.

But if they're using their legs all day, and their arms only
occasionally...

Actually the pro sprinters do tend to have more developed upper bodies
than the other riders in the peloton, but I'm not sure this proves
anything either way. Short-distance runners tend to look more bulky
compared to long-distance ones. I suspect it's something to do with
body-types, different kinds of muscle fibres-- complicated stuff not
obvious to the armchair physicist like myself.

>>> This subject comes up often in this forum. You might search old
>>> editions.
>
>> I remember discussing this before, yes. All I was saying was that I
>> think sprinters are doing _some_ work with their arms, and I think
>> that point has been clarified. I wasn't making claims about whether
>> it was significant or necessary (although I keep an open mind).
>
> If you are climbing a long grade, I think you'll find that changing
> from sitting to standing is a matter of relaxing one set of (back)
> muscles and using others, it does not increase or decrease speed. The
> speed is governed by aerobic capacity.

This sounds very likely to be true. But the sprint to the line is
different-- anaerobic and the requirement is for peak power, not for
sustainability.

 

[Ron Ruff]

[email protected] wrote:
> My guess is that it felt close, but was much more than the "few inches"
> you mentioned. And it really does sound like you need to ride further
> left! This is a basic skill in road riding. Most people posting here
> are well aware of it.

It is really hard for me to judge. I can get passed by hundreds of cars
and literally pay no attention to them, and then out of the blue...
WTF!! It's close... damn close. I don't think I'd notice at all if
somebody missed me by 2 ft... seems like that is pretty common. Like I
said, it's somebody being stupid and careless, or they are *trying* to
scare me. In my opinion, missing a rider by less than a foot should be
assault...

> If dangerously close passes happen a lot to you, it may be that you're
> permitting it too often. Ride far enough left to be safe.

99.9% of motorists seem to realize that they are driving a lethal
weapon, and *do* wait until it is safe to pass. The farther I am to the
right, the easier it is for them to do this when the opportunity
arises. When I'm going fast enough to keep up with traffic, I ride in
the middle of the road, but otherwise I stay as far to the right as I
reasonably can.

It is difficult for me to see how riding in the middle of the road
would favorably impress the other 0.1%. Maybe the careless drivers
would be woken up out of their revere and actually give me some room,
but the drivers with attitude will only acquire more. I've been hounded
(verbally) enough even when I've been taking up as little space as
possible.

I give it a try though... see if there is some way I can make that
work...

BTW... nice website.

 

[Ben C]

On 2007-01-17, Ron Ruff <[email protected]> wrote:
[snip]
> 99.9% of motorists seem to realize that they are driving a lethal
> weapon, and *do* wait until it is safe to pass. The farther I am to the
> right, the easier it is for them to do this when the opportunity
> arises. When I'm going fast enough to keep up with traffic, I ride in
> the middle of the road, but otherwise I stay as far to the right as I
> reasonably can.
>
> It is difficult for me to see how riding in the middle of the road
> would favorably impress the other 0.1%. Maybe the careless drivers
> would be woken up out of their revere and actually give me some room,
> but the drivers with attitude will only acquire more. I've been hounded
> (verbally) enough even when I've been taking up as little space as
> possible.

My technique with buses (which in this country are affiliated with Al
Quaeda) is to move towards the centre of the road a bit when you hear
one rumbling up. Then when it brushes past you with one inch to spare
you have a bit of space to move into to make the gap something more
reasonable.

 

[Tim McNamara]

In article <[email protected]>,
[email protected] wrote:

> Tim McNamara writes:
>
> >>> Work in the mechanical sense and work in the biological sense
> >>> have different connotations. Humans can work very hard to not
> >>> move, from the biological sense of the term.
>
> >> Oh ****, here we go again. WORK = FORCE x DISTANCE
>
> > I know the definition of work in the mechanical sense. We covered
> > it in junior high school science class and it comes up here
> > regularly just to reinforce it.
>
> > I also know the definition of work in the human sense. Normal
> > people who don't read wreck.bikes will tell you it's damned hard
> > work to hold a couple of cement blocks in their arms for a half an
> > hour. People will refer to algebra as hard work, too, even though
> > it involves no moving parts. It boils down to:
>
> > Work = subjective effort
>
> > in the normal sense of the word "work." People live in the world
> > of muscular contraction, not in the world of equations. Equations
> > describe how the world acts, they do not govern how the world acts
> > and they do not define human perception. Map != territory. It's
> > too bad that the formulation of W = F * D uses the word "work" in a
> > way which is oblique to normal human experience. It muddles the
> > conversation.
>
> Lats time I noticed this was "rec.bicycles.tech" in which we discuss
> technical subjects, it is not "rec.bicycles.psychology". Therefore,
> this is a classic red herring that we see here on almost any clearly
> defined technical subject.

rec.bikes.tech indeed, but let's not make it r.b.pedants.

http://www.m-w.com/dictionary/pedant

 

[Bill Sornson]

Tim McNamara wrote:
> In article <[email protected]>,
> [email protected] wrote:

>> Lats time I noticed this was "rec.bicycles.tech" in which we discuss
>> technical subjects, it is not "rec.bicycles.psychology". Therefore,
>> this is a classic red herring that we see here on almost any clearly
>> defined technical subject.

> rec.bikes.tech indeed, but let's not make it r.b.pedants.
>
> http://www.m-w.com/dictionary/pedant

Too late.

 

[[email protected]]

Ron Ruff wrote:
> [email protected] wrote:
> >
> > If dangerously close passes happen a lot to you, it may be that you're
> > permitting it too often. Ride far enough left to be safe.
>
> 99.9% of motorists seem to realize that they are driving a lethal
> weapon, and *do* wait until it is safe to pass. The farther I am to the
> right, the easier it is for them to do this when the opportunity
> arises. When I'm going fast enough to keep up with traffic, I ride in
> the middle of the road, but otherwise I stay as far to the right as I
> reasonably can.
>
> It is difficult for me to see how riding in the middle of the road
> would favorably impress the other 0.1%. Maybe the careless drivers
> would be woken up out of their revere and actually give me some room,
> but the drivers with attitude will only acquire more. I've been hounded
> (verbally) enough even when I've been taking up as little space as
> possible.

As an illustration:

A good friend of mine once took a Road 1 cycling class from me. One of
the basic things covered in that class is, ride far enough _left_ to be
safe. (When safe, you also ride far enough right to be courteous - but
that's only when you can safely do it.)

Not long after, he and his wife were vacationing on their tandem in
another state. On a long narrow two-lane state highway, they were
being repeatedly passed too close for comfort. Drivers were squeezing
past them at speed when there was oncoming traffic preventing use of
the opposite lane. They were both getting a bit scared.

Then my friend told his wife "Frank said the way to stop this is to
ride further left, and block them from passing. Do you want to try
it?" HIs wife, the stoker, nervously agreed to let him block the lane.

He said it absolutely transformed the ride. Passing cars either swung
clear into the opposite lane to pass, or waited behind until it was
safe to do so. He became very enthusiastic about using his right to
the road.

>
> I give it a try though... see if there is some way I can make that
> work...
>
> BTW... nice website.

Thanks. http://www.bicyclinglife.com

- Frank Krygowski

 

[[email protected]]

[email protected] wrote:
> Ben C? writes:
>
> > [snip]
>
> > I have, and it does feel as I pull the bike from side to side that
> > I'm pulling against something-- more than just the force required to
> > tip the bike.
>
> >> You are not performing any significant work with the arms.
>
> > I doubt it's significant in my case, yes.
>
> Not that, I mean as part of propelling your bicycle. There is no
> force times distance. Consider the angle and length change of
> shoulder to hand and the force required to accomplish that. There
> isn't much motion and it is an insignificant force compared to the leg
> force and its stroke.

I think arm (and other) muscles do contribute to propulsion of the
bike, and during times calling for higher power, they do it in a
significant way. Perhaps not 30%, but I wouldn't be at all surprised
if it were on the order of 10 percent.

I think two ways this can happen are these: First, in a sprint
situation, the "reaction" pull of the arms allows greater force to be
applied to the pedals by the legs. Without such reaction, pedal forces
are limited by gravity.

Second, when climbing a steep grade, I think the upper body muscles may
help lift the rider's center of gravity repeatedly for each pedal
stroke. That energy is recovered as the rider's c.g. descends during
the pedal stroke. It's a bit like a person using their arms to help
them ascend a ladder, although not as strong an effect.

A person could probably demonstrate this by comparing their sprints and
their climbing done "normally" (that is, using their upper body) vs. by
trying to avoid upper body use - say, by steering only with fingertips
so little force could be transmitted. I think you'd find yourself
significantly slower in the latter case.

That was certainly the case when I was a young kid. For a while, we
used to "drag race" on our bikes. I was the fastest until the other
kids realized the benefits of pulling up on the bars for that sprint.

I think it's extremely unlikely that sport cyclists the world over
would use the body motion they use in sprints and steep climbs - that
is, visibly use their upper bodies - unless there was subconsciously
discernible payoff for doing so. The payoff is in instantaneous,
short-term power, which is not so strongly limited by aerobic capacity.

True, we don't bulk up by using those muscles. But one can gain
significant strength without significantly increasing bulk. It usually
takes extreme loads applied very consistently to increase muscle bulk.
And anyway, the people that do this the most - the sprint specialists -
do develop a bit more upper body bulk.

- Frank Krygowski

 

[[email protected]]

Ben C? writes:

> [snip]

>>> Well, it's not so black-and-white as that, they also have to keep
>>> their weight down, and if the arms are only slightly useful, you'd
>>> expect the biceps etc. to be only slightly larger than normal,
>>> and only then for the sprinters.

>> It isn't a matter of whether they want to develop muscular bulk or
>> not. If those muscles are working in the manner in which it is
>> perceived, the muscles would grow just as bicyclists leg muscles
>> do. If there is no work taking place there the muscles remain as
>> they are.

> But if they're using their legs all day, and their arms only
> occasionally...

They ride standing often enough to develop muscles if there were any
significant work taking place in that position.

> Actually the pro sprinters do tend to have more developed upper
> bodies than the other riders in the peloton, but I'm not sure this
> proves anything either way. Short-distance runners tend to look
> more bulky compared to long-distance ones. I suspect it's something
> to do with body-types, different kinds of muscle fibres--
> complicated stuff not obvious to the armchair physicist like myself.

As I said, sprinters pump iron to develop these muscles that are
important in sprints because these are done in large gears and require
the higher short term torque that can be summoned anaerobically. It's
not that the arms propel the bicycle but rather that they make the
higher working torque of the legs possible. This torque is not useful
in hill climbs because it cannot be aerobically supported. That's the
difference between sprint and TT or hill climb.

>>>> This subject comes up often in this forum. You might search old
>>>> editions.

>>> I remember discussing this before, yes. All I was saying was that
>>> I think sprinters are doing _some_ work with their arms, and I
>>> think that point has been clarified. I wasn't making claims about
>>> whether it was significant or necessary (although I keep an open
>>> mind).

They may exert more force on the bars to counter pedaling torque but
the do not propel the bicycle. You might consider the lever between
handle bar and BB in comparison to horizontal displacement of the
pedal center to assess the force ratios. Just the same I think you
might show how arm motion can propel the bicycle forward,
qualitatively and quantitatively.

>> If you are climbing a long grade, I think you'll find that changing
>> from sitting to standing is a matter of relaxing one set of (back)
>> muscles and using others, it does not increase or decrease speed.
>> The speed is governed by aerobic capacity.

> This sounds very likely to be true. But the sprint to the line is
> different-- anaerobic and the requirement is for peak power, not for
> sustainability.

It is a sprint... done in a large gear and is most often won on
acceleration. If the distance is far, the finish is done seated, wind
drag being more important after accelerating. For such a sprint,
greater arm strength is an advantage, but then if it's a stage race,
those muscles need to be carried to the finish that is most often not
contested by sprinters except in stages that are criteriums or other
flat courses. Looking at TdF winners of the past, we find mainly
slender riders with legs and lungs, not large biceps.

Jobst Brandt

 

[[email protected]]

Tim McNamara writes:

>>>>> Work in the mechanical sense and work in the biological sense
>>>>> have different connotations. Humans can work very hard to not
>>>>> move, from the biological sense of the term.

>>>> Oh ****, here we go again. WORK = FORCE x DISTANCE > I know the
>>definition of work in the mechanical sense. We covered > it in
>>junior high school science class and it comes up here > regularly
>>just to reinforce it.

>>> I also know the definition of work in the human sense. Normal
>>> people who don't read wreck.bikes will tell you it's damned hard
>>> work to hold a couple of cement blocks in their arms for a half an
>>> hour. People will refer to algebra as hard work, too, even though
>>> it involves no moving parts. It boils down to:

>>> Work = subjective effort

>>> in the normal sense of the word "work." People live in the world
>>> of muscular contraction, not in the world of equations. Equations
>>> describe how the world acts, they do not govern how the world acts
>>> and they do not define human perception. Map != territory. It's
>>> too bad that the formulation of W = F * D uses the word "work" in
>>> a way which is oblique to normal human experience. It muddles the
>>> conversation.

>> Lats time I noticed this was "rec.bicycles.tech" in which we
>> discuss technical subjects, it is not "rec.bicycles.psychology".
>> Therefore, this is a classic red herring that we see here on almost
>> any clearly defined technical subject.

> rec.bikes.tech indeed, but let's not make it r.b.pedants.

http://www.m-w.com/dictionary/pedant

So don't be so pedantic and raise red herrings.

Jobst Brandt

 

[Tim McNamara]

In article <[email protected]>,
[email protected] wrote:

> Tim McNamara writes:
>
> >>>>> Work in the mechanical sense and work in the biological sense
> >>>>> have different connotations. Humans can work very hard to not
> >>>>> move, from the biological sense of the term.
>
> >>>> Oh ****, here we go again. WORK = FORCE x DISTANCE > I know the
> >>definition of work in the mechanical sense. We covered > it in
> >>junior high school science class and it comes up here > regularly
> >>just to reinforce it.
>
> >>> I also know the definition of work in the human sense. Normal
> >>> people who don't read wreck.bikes will tell you it's damned hard
> >>> work to hold a couple of cement blocks in their arms for a half
> >>> an hour. People will refer to algebra as hard work, too, even
> >>> though it involves no moving parts. It boils down to:
>
> >>> Work = subjective effort
>
> >>> in the normal sense of the word "work." People live in the world
> >>> of muscular contraction, not in the world of equations.
> >>> Equations describe how the world acts, they do not govern how the
> >>> world acts and they do not define human perception. Map !=
> >>> territory. It's too bad that the formulation of W = F * D uses
> >>> the word "work" in a way which is oblique to normal human
> >>> experience. It muddles the conversation.
>
> >> Lats time I noticed this was "rec.bicycles.tech" in which we
> >> discuss technical subjects, it is not "rec.bicycles.psychology".
> >> Therefore, this is a classic red herring that we see here on
> >> almost any clearly defined technical subject.
>
> > rec.bikes.tech indeed, but let's not make it r.b.pedants.
>
> http://www.m-w.com/dictionary/pedant
>
> So don't be so pedantic and raise red herrings.

LOL!

 

[Michael Press]

In article
<[email protected]>,
"Ron Ruff" <[email protected]> wrote:

> Maybe you thought I was talking about a very small sample. I'd guess
> there are well over 1,000 licensed racers in the L.A. area. There were
> probably some who were killed that I didn't know about, but I knew of 3
> in the time I lived there. None of them were close friends, but they
> were all people I knew *of* from races and group rides.

And somebody else is going to say "I know of three
riders who were killed in LA." And other people will
report the same fatalities. It's a vicious cycle.

--
Michael Press

 

[Ben C]

On 2007-01-18, [email protected] <[email protected]> wrote:
[snip]
> They may exert more force on the bars to counter pedaling torque but
> the do not propel the bicycle. You might consider the lever between
> handle bar and BB in comparison to horizontal displacement of the
> pedal center to assess the force ratios. Just the same I think you
> might show how arm motion can propel the bicycle forward,
> qualitatively and quantitatively.

Good suggestion. My calculations indicate that pulling a bike vertical
from a 20 degree lean, with a 10.5in bb height and 175mm crank length,
while keeping the foot at a constant height, would result in an
effective down-push on the crank of 27mm.

So a small amount of work, but unlikely to be significant. I think Frank
is right: the main role of the arms in a sprint is to give the legs
something to push against, which is providing force, not work.

[snip]
> For such a sprint, greater arm strength is an advantage, but then if
> it's a stage race, those muscles need to be carried to the finish that
> is most often not contested by sprinters except in stages that are
> criteriums or other flat courses. Looking at TdF winners of the past,
> we find mainly slender riders with legs and lungs, not large biceps.

Yes, but as you say overall TdF winners are rarely sprinters. Usually
they're climbers and/or time trialists.

But I think it's hard to draw anything but the broadest conclusions from
observed muscle bulk on pro riders. Obviously they all use their legs
much more than anything else.

 

[Mark Hickey]

Michael Press <[email protected]> wrote:

>In article
><[email protected]>,
> "Ron Ruff" <[email protected]> wrote:
>
>> Maybe you thought I was talking about a very small sample. I'd guess
>> there are well over 1,000 licensed racers in the L.A. area. There were
>> probably some who were killed that I didn't know about, but I knew of 3
>> in the time I lived there. None of them were close friends, but they
>> were all people I knew *of* from races and group rides.
>
>And somebody else is going to say "I know of three
>riders who were killed in LA." And other people will
>report the same fatalities. It's a vicious cycle.

And it's situational as well. Simply riding out in the middle of the
lane "because it's your right" isn't always the best idea. Sometimes
it's absolutely necessary. It's all about deciding what is going to
make you safer. Opinions differ, but strangely, reality is constant.
;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame