A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Marketplace
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Beware of PowerCranks



 
 
Thread Tools Display Modes
  #131  
Old August 1st 07, 03:54 AM posted to rec.bicycles.racing,rec.bicycles.marketplace,rec.bicycles.tech
Doug Taylor
external usenet poster
 
Posts: 430
Default Beware of PowerCranks

On Tue, 31 Jul 2007 11:30:58 -0700, wrote:

In my opinion, the limiter is the ability to deliver oxygen to the
mitochondria so the mitochonria compensate by using another mechanism
with lactic acid as an end point. Once there are enough mitochondria
in this situation the amount of lactic acid being produced overwhelms
the bodies ability to compensate for this and the "failure cascade"
starts.


Pardon me if I switch topics, but now that Frank is posting I want to
get back to the subject of Powercranks and strength training .

Jobst Brandt has opined - I hope I am not misconstruing him - that the
full circle muscular movement that Powercranks train, is not really
used when pedaling a bicycle. Good old stomping is how regular cranks
work mechanically.

I'm still a beginner on my Powercranks and usually manage a low
cadence. I trained them on the basement trainer over the winter, and
now use them only about twice a month (hint: they are absolutely
perfect to use when taking a spin with your S.O. if she, or he, is a
less strong cyclist. They slow you, or at least me, down enough so
that we actually can ride together.)

Anecdote: I took out my single speed maintain bike this evening for
the first time this season and the first time ever after using
Powercranks. Anyone who climbs on single speeds knows that the
gearing is much higher than what would be used on a multi geared bike,
and that standing and grinding at a very low cadence, rather than
sitting and spinning, is what gets you up and over. I found that an
approximation of a circular pedaling motion works much more
efficiently than stomping in this venue, and that I was noticeably
stronger over terrain that in the past was much more difficult.

So, anecdotally and subjectively, I'm thinking these puppies have made
me stronger.

FWIW.
Ads
  #132  
Old August 3rd 07, 01:14 AM posted to rec.bicycles.racing,rec.bicycles.marketplace,rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 26
Default Beware of PowerCranks

On Jul 31, 7:54 pm, Doug Taylor wrote:
On Tue, 31 Jul 2007 11:30:58 -0700, wrote:

In my opinion, the limiter is the ability to deliver oxygen to the
mitochondria so the mitochonria compensate by using another mechanism
with lactic acid as an end point. Once there are enough mitochondria
in this situation the amount of lactic acid being produced overwhelms
the bodies ability to compensate for this and the "failure cascade"
starts.


Pardon me if I switch topics, but now that Frank is posting I want to
get back to the subject ofPowercranksand strength training .

Jobst Brandt has opined - I hope I am not misconstruing him - that the
full circle muscular movement thatPowercrankstrain, is not really
used when pedaling a bicycle. Good old stomping is how regular cranks
work mechanically.

I'm still a beginner on myPowercranksand usually manage a low
cadence. I trained them on the basement trainer over the winter, and
now use them only about twice a month (hint: they are absolutely
perfect to use when taking a spin with your S.O. if she, or he, is a
less strong cyclist. They slow you, or at least me, down enough so
that we actually can ride together.)

Anecdote: I took out my single speed maintain bike this evening for
the first time this season and the first time ever after usingPowercranks. Anyone who climbs on single speeds knows that the
gearing is much higher than what would be used on a multi geared bike,
and that standing and grinding at a very low cadence, rather than
sitting and spinning, is what gets you up and over. I found that an
approximation of a circular pedaling motion works much more
efficiently than stomping in this venue, and that I was noticeably
stronger over terrain that in the past was much more difficult.

So, anecdotally and subjectively, I'm thinking these puppies have made
me stronger.

FWIW.


First, Jobst is wrong. Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? People get confused when they look at measured pedal
forces and they see everyone with negative forces on the back stroke
and very large forces on the down stroke. They construe this to mean
that stomping is the way to go. What they forget is the effects of
gravity on those measured forces.

By way of example Let's say you measure your forces and find that you
are putting 50 lbs of force on the down stroke each revolution and a
negative 5 lbs on the up stroke. From this you think you are a masher.
However, If you consider that each leg weighs perhaps 25 lbs what
this really means is you are really pulling up with 20 lbs force when
you see those negative 5 lbs on the pedal and that 25 lbs of the
downward force is actually the weight of the leg such that you are
only actually pushing with 20 lbs of muscular force on the downward
portion. So you are actively pushing with 25 lbs force and pulling
with 20 lbs force, what almost anyone would call close to pedaling in
circles, even though the forces on the pedals do not look like that
at all. If all PowerCranks does is make the rider completely unweight
then they only have to pull up another 5 lbs and now they are pushing
with 25 lbs force and pulling with 25 lbs force, what anyone would
consider pedaling in circles I am sure, even though the forces on the
pedals would be 50 on the downstroke and 0 on the up.

  #133  
Old August 3rd 07, 09:37 AM posted to rec.bicycles.racing,rec.bicycles.marketplace,rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 631
Default Beware of PowerCranks

On Aug 3, 2:14 am, wrote:
Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? [...] What they forget is the effects of
gravity on those measured forces.


You're saying that on the moon your cranks would be one-sixth as
effective?

  #134  
Old August 3rd 07, 05:35 PM posted to rec.bicycles.racing,rec.bicycles.marketplace,rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 26
Default Beware of PowerCranks

On Aug 3, 1:37 am, wrote:
On Aug 3, 2:14 am, wrote:

Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? [...] What they forget is the effects of
gravity on those measured forces.


You're saying that on the moon your cranks would be one-sixth as
effective?


One-sixth as effective as what? bicycle cranks? training devices to
train "circular" pedaling on earth? training devices for space?

  #135  
Old August 4th 07, 06:21 AM posted to rec.bicycles.racing,rec.bicycles.marketplace,rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 631
Default Beware of PowerCranks

On Aug 3, 6:35 pm, wrote:
On Aug 3, 1:37 am, wrote:

On Aug 3, 2:14 am, wrote:


Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? [...] What they forget is the effects of
gravity on those measured forces.


You're saying that on the moon your cranks would be one-sixth as
effective?


One-sixth as effective as what? bicycle cranks? training devices to
train "circular" pedaling on earth? training devices for space?


I don't know. I'm asking. You're saying that everyone but you forgets
acceleration due to gravity. So can you estimate the difference in
power an astronaut could make if he used a regularly-cranked ergometer
on the ISS?

  #136  
Old August 4th 07, 06:51 PM posted to rec.bicycles.racing,rec.bicycles.marketplace,rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 26
Default Beware of PowerCranks

On Aug 3, 10:21 pm, wrote:
On Aug 3, 6:35 pm, wrote:

On Aug 3, 1:37 am, wrote:


On Aug 3, 2:14 am, wrote:


Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? [...] What they forget is the effects of
gravity on those measured forces.


You're saying that on the moon your cranks would be one-sixth as
effective?


One-sixth as effective as what? bicycle cranks? training devices to
train "circular" pedaling on earth? training devices for space?


I don't know. I'm asking. You're saying that everyone but you forgets
acceleration due to gravity. So can you estimate the difference in
power an astronaut could make if he used a regularly-cranked ergometer
on the ISS?


regarding your comment that everyone but me "forgets" acceleration due
to gravity - Have you ever seen anyone else mention that the forces on
the pedals do not actually represent the muscular forces involved? I
haven't, at least in any of these threads.

I am not sure what an astronaut can or would do on the ISS. Their
problem is going to be that unless they are somehow glued to the seat
their forces have to be completely balanced or they are going to fly
off the seat. I am sure this takes a little (or a lot of) getting used
to and since their main job is not to see how good they can get on the
exercise bike but, rather, simply maintain enough muscular and
cardiovascular fitness such that they might be able to actually stand
up when they return to earth, I suspect most of them see substantial
drops in power compared to what they could do on the earth before they
went into space.

  #137  
Old August 4th 07, 07:23 PM posted to rec.bicycles.racing,rec.bicycles.marketplace,rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 631
Default Beware of PowerCranks

On Aug 4, 7:51 pm, wrote:
On Aug 3, 10:21 pm, wrote:



On Aug 3, 6:35 pm, wrote:


On Aug 3, 1:37 am, wrote:


On Aug 3, 2:14 am, wrote:


Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? [...] What they forget is the effects of
gravity on those measured forces.


You're saying that on the moon your cranks would be one-sixth as
effective?


One-sixth as effective as what? bicycle cranks? training devices to
train "circular" pedaling on earth? training devices for space?


I don't know. I'm asking. You're saying that everyone but you forgets
acceleration due to gravity. So can you estimate the difference in
power an astronaut could make if he used a regularly-cranked ergometer
on the ISS?


regarding your comment that everyone but me "forgets" acceleration due
to gravity - Have you ever seen anyone else mention that the forces on
the pedals do not actually represent the muscular forces involved? I
haven't, at least in any of these threads.

I am not sure what an astronaut can or would do on the ISS. Their
problem is going to be that unless they are somehow glued to the seat
their forces have to be completely balanced or they are going to fly
off the seat.


Then what would an astronaut be able to do on Mars?


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Beware of PowerCranks [email protected] Racing 205 August 4th 07 07:23 PM
Beware of PowerCranks [email protected] Techniques 202 August 4th 07 07:23 PM
FS: POwerCranks- Mike Marketplace 0 December 24th 05 05:52 AM
FS: Powercranks steve Marketplace 0 December 19th 05 05:53 AM
POWERCRANKS Marketplace 0 January 20th 04 02:33 AM


All times are GMT +1. The time now is 12:39 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.