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Something I've been wondering about.



 
 
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  #41  
Old March 21st 19, 01:33 AM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 5,870
Default Something I've been wondering about.

On Wednesday, March 20, 2019 at 3:54:39 PM UTC-7, James wrote:
On 21/3/19 9:09 am, jbeattie wrote:
On Wednesday, March 20, 2019 at 1:51:54 PM UTC-7,
wrote:



Jay, you said that you raced professionally in one of these
postings. Was that a joke or were you serious?


I raced with professionals on occasion, but I was never a
professional -- unless my staggering winnings as an amateur elevate
me to pro status. I once won a crate of Kettle chips, some water
bottles, prime change and some free swag that everybody got. I got
some t-shirts that didn't fit. I suppose that's not good enough to be
considered a pro.


Same here!

And yes, I know about pedaling technique and am tired of hearing
about it since it changes every ten minutes -- along with fit. Pedal
circles, scrape dog **** off your sole, pedal up and down, etc., etc.
I'm waiting for someone to chime in again about the mystical pedaling
technique of Jacques Anquetil. We had that long thread about 15-20
years ago with that guy who was going on about Jacques Anquetil. I
think he was trying to sell a book. Apparently there are still some
dark mysteries about Jacques' pedaling technique.


I trained and raced with a fellow who had a very ordinary pedalling
style, to the point I've seen his legs stop at the dead spots and cause
the freewheel to clunk as his legs start moving again.

He won several big races as a masters competitor.


I'm too familiar with that clunk. I get tired and pedal squares.

-- Jay Beattie.
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  #42  
Old March 21st 19, 01:34 AM posted to rec.bicycles.tech
Mark J.
external usenet poster
 
Posts: 840
Default Something I've been wondering about.

On 3/20/2019 2:13 PM, AMuzi wrote:
On 3/20/2019 3:42 PM, jbeattie wrote:
On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7,
wrote:
On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B. Slocomb wrote:
On Wed, 20 Mar 2019 07:47:58 +1100, James
wrote:

On 20/3/19 1:16 am, wrote:
On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John B. Slocomb
wrote:
Last Sunday I was on my usual weekly "long ride" (which was hardly
as long as it used to be). And I was sort of looking down and the
chain was on the big chain ring and the 5th cassette sprocket (9
speed cassette) and I got to thinking.

Note the friction losses for a chain drive are usually considered
to be very low, the usual efficiency of a chain drive is usually
reckoned to be "up to" 98%. But the instructions for installing a
chain drive is always to ensure that the drive and driven sprockets
are exactly in line.

But the conventional bicycle with it's multiple front and rear
sprockets does not have the sprockets aligned except in two
instances, assuming the usual chain line dimensions. When on the
large front chain ring and (usually) the center cassette sprocket
on an uneven numbered cassette, and when on the small front chain
ring and a larger cassette sprocket. Perhaps two sprockets larger
than center.

So, if the usually chain efficiency figures are used the chain is
delivering the 98%+ efficiency only twice in a possible 18 speed
range.

What efficiency is being delivered during the periods when the
chain is not perfectly aligned?

And should one worry about it?


-- Cheers, John B.

The short answer is no.

The long answer is:

The efficiency due to misalignment in a derrailleur/freehub system is
negligible, here's why:

1. The 98% efficiency you mentioned is in fixed systems with a drive
providing constant smooth torque.

2. Once a freehub system is installed (like a single-speed (NOT fixed
gear)), the efficiency depends almost entirely on the the
bio-mechanical pedaling efficiency.Â* In other words, if you don't
apply even power throughout the pedal stroke, the efficiency of the
entire system drops off dramatically, at this point, losses due to
chain misalignment are barely measurable, let alone being perceptible
by the rider.

I believe John is focused on the efficiency of the chain drive system
alone, not the biomechanical efficiency of the person plus the chain.

Certainly I was... After all one's "pedal stroke" while it can be
altered by practice, to an extent, is essentially a down and back
power stroke for even the best riders and a sort of "built in" part of
one's riding.


3. Make matters worse by introducing a spring tension system. Now in
addition to the bio mechanical inefficiencies, you're adding the
ability of the chain drive to take up slack in the system, which
allows _you_ to pedal even more inefficiently.

Here's a graphic representation:

https://hanswinter.wordpress.com/200...your-spinscan/


I think that, and the rest of your post is complete ********.


Ahh, that may be the common transportation rider pedal stroke but
pedaling circles is normal for a high performance rider. Though I can
no longer hold it up for long and now reserve it for climbing or
sprinting.


I always pedal circles because my crank arms describe a circle.Â* If
you don't like circles, I recommend: http://tinyurl.com/y2nop9m8



Bad ideas live forever:
https://www.youtube.com/watch?v=VAlFpcph1LM


Ahh, the Alenax. I always wanted to ride one of those.... once, just to
see what it was like. The sheer Rube Goldberg-ness of it amuses me.

A friend had a funky crank ?or bottom bracket? that allowed both crank
arms to turn, well, semi-independently. Both drove the bike, but
neither drove the other, so you had to consciously lift each leg. I
believe it was marketed as a training tool (and you could "Alenax" it,
with both arms being simultaneously on the downstroke.) Oddly, I never
wanted to try /that/.

Mark J.
  #43  
Old March 21st 19, 01:36 AM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default Something I've been wondering about.

On 3/20/2019 7:34 PM, Mark J. wrote:
On 3/20/2019 2:13 PM, AMuzi wrote:
On 3/20/2019 3:42 PM, jbeattie wrote:
On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7,
wrote:
On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B.
Slocomb wrote:
On Wed, 20 Mar 2019 07:47:58 +1100, James

wrote:

On 20/3/19 1:16 am, wrote:
On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John
B. Slocomb
wrote:
Last Sunday I was on my usual weekly "long ride"
(which was hardly
as long as it used to be). And I was sort of looking
down and the
chain was on the big chain ring and the 5th cassette
sprocket (9
speed cassette) and I got to thinking.

Note the friction losses for a chain drive are
usually considered
to be very low, the usual efficiency of a chain
drive is usually
reckoned to be "up to" 98%. But the instructions for
installing a
chain drive is always to ensure that the drive and
driven sprockets
are exactly in line.

But the conventional bicycle with it's multiple
front and rear
sprockets does not have the sprockets aligned except
in two
instances, assuming the usual chain line dimensions.
When on the
large front chain ring and (usually) the center
cassette sprocket
on an uneven numbered cassette, and when on the
small front chain
ring and a larger cassette sprocket. Perhaps two
sprockets larger
than center.

So, if the usually chain efficiency figures are used
the chain is
delivering the 98%+ efficiency only twice in a
possible 18 speed
range.

What efficiency is being delivered during the
periods when the
chain is not perfectly aligned?

And should one worry about it?


-- Cheers, John B.

The short answer is no.

The long answer is:

The efficiency due to misalignment in a
derrailleur/freehub system is
negligible, here's why:

1. The 98% efficiency you mentioned is in fixed
systems with a drive
providing constant smooth torque.

2. Once a freehub system is installed (like a
single-speed (NOT fixed
gear)), the efficiency depends almost entirely on the
the
bio-mechanical pedaling efficiency. In other words,
if you don't
apply even power throughout the pedal stroke, the
efficiency of the
entire system drops off dramatically, at this point,
losses due to
chain misalignment are barely measurable, let alone
being perceptible
by the rider.

I believe John is focused on the efficiency of the
chain drive system
alone, not the biomechanical efficiency of the person
plus the chain.

Certainly I was... After all one's "pedal stroke" while
it can be
altered by practice, to an extent, is essentially a
down and back
power stroke for even the best riders and a sort of
"built in" part of
one's riding.


3. Make matters worse by introducing a spring tension
system. Now in
addition to the bio mechanical inefficiencies, you're
adding the
ability of the chain drive to take up slack in the
system, which
allows _you_ to pedal even more inefficiently.

Here's a graphic representation:

https://hanswinter.wordpress.com/200...your-spinscan/


I think that, and the rest of your post is complete
********.


Ahh, that may be the common transportation rider pedal
stroke but pedaling circles is normal for a high
performance rider. Though I can no longer hold it up for
long and now reserve it for climbing or sprinting.


I always pedal circles because my crank arms describe a
circle. If you don't like circles, I recommend:
http://tinyurl.com/y2nop9m8



Bad ideas live forever:
https://www.youtube.com/watch?v=VAlFpcph1LM


Ahh, the Alenax. I always wanted to ride one of those....
once, just to see what it was like. The sheer Rube
Goldberg-ness of it amuses me.

A friend had a funky crank ?or bottom bracket? that allowed
both crank arms to turn, well, semi-independently. Both
drove the bike, but neither drove the other, so you had to
consciously lift each leg. I believe it was marketed as a
training tool (and you could "Alenax" it, with both arms
being simultaneously on the downstroke.) Oddly, I never
wanted to try /that/.

Mark J.


Houdaille Power Cam cranks?

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #44  
Old March 21st 19, 02:20 AM posted to rec.bicycles.tech
James[_8_]
external usenet poster
 
Posts: 6,153
Default Something I've been wondering about.

On 21/3/19 11:33 am, jbeattie wrote:


I'm too familiar with that clunk. I get tired and pedal squares.


You will need square cranks for that.

http://pardo.net/bike/pic/mobi/d.pmp-cranks/index.html

--
JS
  #45  
Old March 21st 19, 06:42 AM posted to rec.bicycles.tech
Sir Ridesalot
external usenet poster
 
Posts: 5,270
Default Something I've been wondering about.

On Wednesday, March 20, 2019 at 5:13:41 PM UTC-4, AMuzi wrote:
On 3/20/2019 3:42 PM, jbeattie wrote:
On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7, wrote:
On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B. Slocomb wrote:
On Wed, 20 Mar 2019 07:47:58 +1100, James
wrote:

On 20/3/19 1:16 am, wrote:
On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John B. Slocomb
wrote:
Last Sunday I was on my usual weekly "long ride" (which was hardly
as long as it used to be). And I was sort of looking down and the
chain was on the big chain ring and the 5th cassette sprocket (9
speed cassette) and I got to thinking.

Note the friction losses for a chain drive are usually considered
to be very low, the usual efficiency of a chain drive is usually
reckoned to be "up to" 98%. But the instructions for installing a
chain drive is always to ensure that the drive and driven sprockets
are exactly in line.

But the conventional bicycle with it's multiple front and rear
sprockets does not have the sprockets aligned except in two
instances, assuming the usual chain line dimensions. When on the
large front chain ring and (usually) the center cassette sprocket
on an uneven numbered cassette, and when on the small front chain
ring and a larger cassette sprocket. Perhaps two sprockets larger
than center.

So, if the usually chain efficiency figures are used the chain is
delivering the 98%+ efficiency only twice in a possible 18 speed
range.

What efficiency is being delivered during the periods when the
chain is not perfectly aligned?

And should one worry about it?


-- Cheers, John B.

The short answer is no.

The long answer is:

The efficiency due to misalignment in a derrailleur/freehub system is
negligible, here's why:

1. The 98% efficiency you mentioned is in fixed systems with a drive
providing constant smooth torque.

2. Once a freehub system is installed (like a single-speed (NOT fixed
gear)), the efficiency depends almost entirely on the the
bio-mechanical pedaling efficiency. In other words, if you don't
apply even power throughout the pedal stroke, the efficiency of the
entire system drops off dramatically, at this point, losses due to
chain misalignment are barely measurable, let alone being perceptible
by the rider.

I believe John is focused on the efficiency of the chain drive system
alone, not the biomechanical efficiency of the person plus the chain.

Certainly I was... After all one's "pedal stroke" while it can be
altered by practice, to an extent, is essentially a down and back
power stroke for even the best riders and a sort of "built in" part of
one's riding.


3. Make matters worse by introducing a spring tension system. Now in
addition to the bio mechanical inefficiencies, you're adding the
ability of the chain drive to take up slack in the system, which
allows _you_ to pedal even more inefficiently.

Here's a graphic representation:

https://hanswinter.wordpress.com/200...your-spinscan/

I think that, and the rest of your post is complete ********.


Ahh, that may be the common transportation rider pedal stroke but pedaling circles is normal for a high performance rider. Though I can no longer hold it up for long and now reserve it for climbing or sprinting.


I always pedal circles because my crank arms describe a circle. If you don't like circles, I recommend: http://tinyurl.com/y2nop9m8



Bad ideas live forever:
https://www.youtube.com/watch?v=VAlFpcph1LM

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


Looks like the IDEAL solution for someone who has limited knee motion to be able to still ride an upright bicycle.

Cheers
  #46  
Old March 21st 19, 08:18 AM posted to rec.bicycles.tech
John B. Slocomb
external usenet poster
 
Posts: 805
Default Something I've been wondering about.

On Wed, 20 Mar 2019 22:42:12 -0700 (PDT), Sir Ridesalot
wrote:

On Wednesday, March 20, 2019 at 5:13:41 PM UTC-4, AMuzi wrote:
On 3/20/2019 3:42 PM, jbeattie wrote:
On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7, wrote:
On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B. Slocomb wrote:
On Wed, 20 Mar 2019 07:47:58 +1100, James
wrote:

On 20/3/19 1:16 am, wrote:
On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John B. Slocomb
wrote:
Last Sunday I was on my usual weekly "long ride" (which was hardly
as long as it used to be). And I was sort of looking down and the
chain was on the big chain ring and the 5th cassette sprocket (9
speed cassette) and I got to thinking.

Note the friction losses for a chain drive are usually considered
to be very low, the usual efficiency of a chain drive is usually
reckoned to be "up to" 98%. But the instructions for installing a
chain drive is always to ensure that the drive and driven sprockets
are exactly in line.

But the conventional bicycle with it's multiple front and rear
sprockets does not have the sprockets aligned except in two
instances, assuming the usual chain line dimensions. When on the
large front chain ring and (usually) the center cassette sprocket
on an uneven numbered cassette, and when on the small front chain
ring and a larger cassette sprocket. Perhaps two sprockets larger
than center.

So, if the usually chain efficiency figures are used the chain is
delivering the 98%+ efficiency only twice in a possible 18 speed
range.

What efficiency is being delivered during the periods when the
chain is not perfectly aligned?

And should one worry about it?


-- Cheers, John B.

The short answer is no.

The long answer is:

The efficiency due to misalignment in a derrailleur/freehub system is
negligible, here's why:

1. The 98% efficiency you mentioned is in fixed systems with a drive
providing constant smooth torque.

2. Once a freehub system is installed (like a single-speed (NOT fixed
gear)), the efficiency depends almost entirely on the the
bio-mechanical pedaling efficiency. In other words, if you don't
apply even power throughout the pedal stroke, the efficiency of the
entire system drops off dramatically, at this point, losses due to
chain misalignment are barely measurable, let alone being perceptible
by the rider.

I believe John is focused on the efficiency of the chain drive system
alone, not the biomechanical efficiency of the person plus the chain.

Certainly I was... After all one's "pedal stroke" while it can be
altered by practice, to an extent, is essentially a down and back
power stroke for even the best riders and a sort of "built in" part of
one's riding.


3. Make matters worse by introducing a spring tension system. Now in
addition to the bio mechanical inefficiencies, you're adding the
ability of the chain drive to take up slack in the system, which
allows _you_ to pedal even more inefficiently.

Here's a graphic representation:

https://hanswinter.wordpress.com/200...your-spinscan/

I think that, and the rest of your post is complete ********.


Ahh, that may be the common transportation rider pedal stroke but pedaling circles is normal for a high performance rider. Though I can no longer hold it up for long and now reserve it for climbing or sprinting.


I always pedal circles because my crank arms describe a circle. If you don't like circles, I recommend: http://tinyurl.com/y2nop9m8



Bad ideas live forever:
https://www.youtube.com/watch?v=VAlFpcph1LM

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


Looks like the IDEAL solution for someone who has limited knee motion to be able to still ride an upright bicycle.

Cheers



There is a guy in the village that has no lower legs. He doesn't ride
a bicycle of course but has a tricycle that has two vertical levers
attached to some sort of "lower end/pedal arm" mechanism and sort of
rows himself along.

--
Cheers,
John B.


  #47  
Old March 21st 19, 03:23 PM posted to rec.bicycles.tech
Radey Shouman
external usenet poster
 
Posts: 1,747
Default Something I've been wondering about.

John B. Slocomb writes:

On Wed, 20 Mar 2019 22:42:12 -0700 (PDT), Sir Ridesalot
wrote:

On Wednesday, March 20, 2019 at 5:13:41 PM UTC-4, AMuzi wrote:
On 3/20/2019 3:42 PM, jbeattie wrote:
On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7, wrote:
On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B. Slocomb wrote:
On Wed, 20 Mar 2019 07:47:58 +1100, James
wrote:

On 20/3/19 1:16 am, wrote:
On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John B. Slocomb
wrote:
Last Sunday I was on my usual weekly "long ride" (which was hardly
as long as it used to be). And I was sort of looking down and the
chain was on the big chain ring and the 5th cassette sprocket (9
speed cassette) and I got to thinking.

Note the friction losses for a chain drive are usually considered
to be very low, the usual efficiency of a chain drive is usually
reckoned to be "up to" 98%. But the instructions for installing a
chain drive is always to ensure that the drive and driven sprockets
are exactly in line.

But the conventional bicycle with it's multiple front and rear
sprockets does not have the sprockets aligned except in two
instances, assuming the usual chain line dimensions. When on the
large front chain ring and (usually) the center cassette sprocket
on an uneven numbered cassette, and when on the small front chain
ring and a larger cassette sprocket. Perhaps two sprockets larger
than center.

So, if the usually chain efficiency figures are used the chain is
delivering the 98%+ efficiency only twice in a possible 18 speed
range.

What efficiency is being delivered during the periods when the
chain is not perfectly aligned?

And should one worry about it?


-- Cheers, John B.

The short answer is no.

The long answer is:

The efficiency due to misalignment in a derrailleur/freehub system is
negligible, here's why:

1. The 98% efficiency you mentioned is in fixed systems with a drive
providing constant smooth torque.

2. Once a freehub system is installed (like a single-speed (NOT fixed
gear)), the efficiency depends almost entirely on the the
bio-mechanical pedaling efficiency. In other words, if you don't
apply even power throughout the pedal stroke, the efficiency of the
entire system drops off dramatically, at this point, losses due to
chain misalignment are barely measurable, let alone being perceptible
by the rider.

I believe John is focused on the efficiency of the chain drive system
alone, not the biomechanical efficiency of the person plus the chain.

Certainly I was... After all one's "pedal stroke" while it can be
altered by practice, to an extent, is essentially a down and back
power stroke for even the best riders and a sort of "built in" part of
one's riding.


3. Make matters worse by introducing a spring tension system. Now in
addition to the bio mechanical inefficiencies, you're adding the
ability of the chain drive to take up slack in the system, which
allows _you_ to pedal even more inefficiently.

Here's a graphic representation:

https://hanswinter.wordpress.com/200...your-spinscan/

I think that, and the rest of your post is complete ********.

Ahh, that may be the common transportation rider pedal stroke
but pedaling circles is normal for a high performance
rider. Though I can no longer hold it up for long and now
reserve it for climbing or sprinting.

I always pedal circles because my crank arms describe a circle.
If you don't like circles, I recommend:
http://tinyurl.com/y2nop9m8


Bad ideas live forever:
https://www.youtube.com/watch?v=VAlFpcph1LM

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


Looks like the IDEAL solution for someone who has limited knee motion
to be able to still ride an upright bicycle.

Cheers



There is a guy in the village that has no lower legs. He doesn't ride
a bicycle of course but has a tricycle that has two vertical levers
attached to some sort of "lower end/pedal arm" mechanism and sort of
rows himself along.


With his hands? The only handcycles I've seen all use a circular
motion, like normal pedal cycles. But I'm sure that doesn't work for
everyone.
  #48  
Old March 21st 19, 11:39 PM posted to rec.bicycles.tech
John B. Slocomb
external usenet poster
 
Posts: 805
Default Something I've been wondering about.

On Thu, 21 Mar 2019 10:23:21 -0400, Radey Shouman
wrote:

John B. Slocomb writes:

On Wed, 20 Mar 2019 22:42:12 -0700 (PDT), Sir Ridesalot
wrote:

On Wednesday, March 20, 2019 at 5:13:41 PM UTC-4, AMuzi wrote:
On 3/20/2019 3:42 PM, jbeattie wrote:
On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7, wrote:
On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B. Slocomb wrote:
On Wed, 20 Mar 2019 07:47:58 +1100, James
wrote:

On 20/3/19 1:16 am, wrote:
On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John B. Slocomb
wrote:
Last Sunday I was on my usual weekly "long ride" (which was hardly
as long as it used to be). And I was sort of looking down and the
chain was on the big chain ring and the 5th cassette sprocket (9
speed cassette) and I got to thinking.

Note the friction losses for a chain drive are usually considered
to be very low, the usual efficiency of a chain drive is usually
reckoned to be "up to" 98%. But the instructions for installing a
chain drive is always to ensure that the drive and driven sprockets
are exactly in line.

But the conventional bicycle with it's multiple front and rear
sprockets does not have the sprockets aligned except in two
instances, assuming the usual chain line dimensions. When on the
large front chain ring and (usually) the center cassette sprocket
on an uneven numbered cassette, and when on the small front chain
ring and a larger cassette sprocket. Perhaps two sprockets larger
than center.

So, if the usually chain efficiency figures are used the chain is
delivering the 98%+ efficiency only twice in a possible 18 speed
range.

What efficiency is being delivered during the periods when the
chain is not perfectly aligned?

And should one worry about it?


-- Cheers, John B.

The short answer is no.

The long answer is:

The efficiency due to misalignment in a derrailleur/freehub system is
negligible, here's why:

1. The 98% efficiency you mentioned is in fixed systems with a drive
providing constant smooth torque.

2. Once a freehub system is installed (like a single-speed (NOT fixed
gear)), the efficiency depends almost entirely on the the
bio-mechanical pedaling efficiency. In other words, if you don't
apply even power throughout the pedal stroke, the efficiency of the
entire system drops off dramatically, at this point, losses due to
chain misalignment are barely measurable, let alone being perceptible
by the rider.

I believe John is focused on the efficiency of the chain drive system
alone, not the biomechanical efficiency of the person plus the chain.

Certainly I was... After all one's "pedal stroke" while it can be
altered by practice, to an extent, is essentially a down and back
power stroke for even the best riders and a sort of "built in" part of
one's riding.


3. Make matters worse by introducing a spring tension system. Now in
addition to the bio mechanical inefficiencies, you're adding the
ability of the chain drive to take up slack in the system, which
allows _you_ to pedal even more inefficiently.

Here's a graphic representation:

https://hanswinter.wordpress.com/200...your-spinscan/

I think that, and the rest of your post is complete ********.

Ahh, that may be the common transportation rider pedal stroke
but pedaling circles is normal for a high performance
rider. Though I can no longer hold it up for long and now
reserve it for climbing or sprinting.

I always pedal circles because my crank arms describe a circle.
If you don't like circles, I recommend:
http://tinyurl.com/y2nop9m8


Bad ideas live forever:
https://www.youtube.com/watch?v=VAlFpcph1LM

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

Looks like the IDEAL solution for someone who has limited knee motion
to be able to still ride an upright bicycle.

Cheers



There is a guy in the village that has no lower legs. He doesn't ride
a bicycle of course but has a tricycle that has two vertical levers
attached to some sort of "lower end/pedal arm" mechanism and sort of
rows himself along.


With his hands? The only handcycles I've seen all use a circular
motion, like normal pedal cycles. But I'm sure that doesn't work for
everyone.


Yup. the "oars" are vertical levers pivoted perhaps 1 foot above the
bottom of the lever and that lower end is connected to what seems to
be a conventional BB through horizontal arms. He seems to pull one
lever and than the other.
I've only seen him a couple of times and I'm not sure how he steers
the thing.

--
Cheers,
John B.


  #49  
Old March 22nd 19, 12:31 AM posted to rec.bicycles.tech
Mark J.
external usenet poster
 
Posts: 840
Default Something I've been wondering about.

On 3/20/2019 5:36 PM, AMuzi wrote:
On 3/20/2019 7:34 PM, Mark J. wrote:
On 3/20/2019 2:13 PM, AMuzi wrote:
On 3/20/2019 3:42 PM, jbeattie wrote:
On Wednesday, March 20, 2019 at 9:25:20 AM UTC-7,
wrote:
On Tuesday, March 19, 2019 at 4:38:21 PM UTC-7, John B.
Slocomb wrote:
On Wed, 20 Mar 2019 07:47:58 +1100, James

wrote:

On 20/3/19 1:16 am, wrote:
On Tuesday, March 19, 2019 at 7:32:42 AM UTC-4, John
B. Slocomb
wrote:
Last Sunday I was on my usual weekly "long ride"
(which was hardly
as long as it used to be). And I was sort of looking
down and the
chain was on the big chain ring and the 5th cassette
sprocket (9
speed cassette) and I got to thinking.

Note the friction losses for a chain drive are
usually considered
to be very low, the usual efficiency of a chain
drive is usually
reckoned to be "up to" 98%. But the instructions for
installing a
chain drive is always to ensure that the drive and
driven sprockets
are exactly in line.

But the conventional bicycle with it's multiple
front and rear
sprockets does not have the sprockets aligned except
in two
instances, assuming the usual chain line dimensions.
When on the
large front chain ring and (usually) the center
cassette sprocket
on an uneven numbered cassette, and when on the
small front chain
ring and a larger cassette sprocket. Perhaps two
sprockets larger
than center.

So, if the usually chain efficiency figures are used
the chain is
delivering the 98%+ efficiency only twice in a
possible 18 speed
range.

What efficiency is being delivered during the
periods when the
chain is not perfectly aligned?

And should one worry about it?


-- Cheers, John B.

The short answer is no.

The long answer is:

The efficiency due to misalignment in a
derrailleur/freehub system is
negligible, here's why:

1. The 98% efficiency you mentioned is in fixed
systems with a drive
providing constant smooth torque.

2. Once a freehub system is installed (like a
single-speed (NOT fixed
gear)), the efficiency depends almost entirely on the
the
bio-mechanical pedaling efficiency.ÂÂ* In other words,
if you don't
apply even power throughout the pedal stroke, the
efficiency of the
entire system drops off dramatically, at this point,
losses due to
chain misalignment are barely measurable, let alone
being perceptible
by the rider.

I believe John is focused on the efficiency of the
chain drive system
alone, not the biomechanical efficiency of the person
plus the chain.

Certainly I was... After all one's "pedal stroke" while
it can be
altered by practice, to an extent, is essentially a
down and back
power stroke for even the best riders and a sort of
"built in" part of
one's riding.


3. Make matters worse by introducing a spring tension
system. Now in
addition to the bio mechanical inefficiencies, you're
adding the
ability of the chain drive to take up slack in the
system, which
allows _you_ to pedal even more inefficiently.

Here's a graphic representation:

https://hanswinter.wordpress.com/200...your-spinscan/



I think that, and the rest of your post is complete
********.

Ahh, that may be the common transportation rider pedal
stroke but pedaling circles is normal for a high
performance rider. Though I can no longer hold it up for
long and now reserve it for climbing or sprinting.

I always pedal circles because my crank arms describe a
circle.ÂÂ* If you don't like circles, I recommend:
http://tinyurl.com/y2nop9m8


Bad ideas live forever:
https://www.youtube.com/watch?v=VAlFpcph1LM


Ahh, the Alenax.Â* I always wanted to ride one of those....
once, just to see what it was like.Â* The sheer Rube
Goldberg-ness of it amuses me.

A friend had a funky crank ?or bottom bracket? that allowed
both crank arms to turn, well, semi-independently.Â* Both
drove the bike, but neither drove the other, so you had to
consciously lift each leg.Â* I believe it was marketed as a
training tool (and you could "Alenax" it, with both arms
being simultaneously on the downstroke.)Â* Oddly, I never
wanted to try /that/.

Mark J.


Houdaille Power Cam cranks?


Yes, that name rings a bell.

Mark J.
  #50  
Old March 22nd 19, 09:19 PM posted to rec.bicycles.tech
[email protected]
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Posts: 1,261
Default Something I've been wondering about.

On Wednesday, March 20, 2019 at 2:22:30 PM UTC-7, James wrote:

Todd Carver says but provides no proof.


I have looked pretty carefully into this. On very hard climbs pedaling circles allows you to maintain your headway. I suppose in that way it can save power as opposed to just pushing down.

But I find that when comparing myself to people I ride with that do not pedal circles that we seem to get tired at the same time. Pulling up is using O2 and lactase in the same manner as pushing down harder.

Now as I get more fit, I can ride a little faster but that is probably from the reduced effort of not having to re-accelerate with every pedal stroke.
 




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