PowerCranks: Worth the Money?

patch70

This is where you have it wrong! By applying power to the upstroke, you end up with less power in the downstroke. The net result is less power overall.

100%

Doesn't this just emphasise that the pulling up muscles need specific training like they would get with PC's?
Any muscle that is not used to performing a certain exercise will tire quickly!

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When I started steel sucked! Then Alloy rocked! Then Alloy sucked! Then carbon rocked! Then carbon sucked! Then Steel rocked! now i ride carbon????

i'm here coz i ride...

100%

So by pulling up with the left leg, the right leg loses power????

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When I started steel sucked! Then Alloy rocked! Then Alloy sucked! Then carbon rocked! Then carbon sucked! Then Steel rocked! now i ride carbon????

i'm here coz i ride...

steve

That is, unless your doing it one legged!

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Steve

CyclingForums.com

beerco

Let me dumb it down a notch for you. Go to your bike, take off the chain and spin the crank. Does it go once and then stop? Now add 50lb weights to each pedal and repeat this experiment. Does it still keep rotating freely or does it rotate once and stop?

THE WEIGHT OF THE PASSIVE LEG IS CANCELED BY THE WEIGHT OF THE ACTIVE LEG.

And even if it wasn't, why would you think that spending energy lifting with your little hip flexor would somehow be "more efficient" than pushing with your big 'ol quad?

Why do you think adding yet another weaker muscle to the mix would help rather than hinder?

Do you even know what efficiency means? (and no using the word efficiency to try and define it)

You got any patents on some perpetual motion machines too?



You know, one of the interesting thing about science is that if the studies are done correctly (which the Coyle is, try reading it some time) you don't have to repeat it yourself to learn from it. Imagine if an engineer had to build bridges that failed in every fashion before he could build one that holds.

n crowley

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You have got to do this test one legged, if you don't, you get
the unweighting effect working on the other pedal which causes
a downward pressure on that pedal ( the weight of the leg),
even though you are not applying any conscious downward
pressure to that pedal.

patch70

Yes - that is correct.

100%

HOW??????????????

WHY?????????????

__________________
When I started steel sucked! Then Alloy rocked! Then Alloy sucked! Then carbon rocked! Then carbon sucked! Then Steel rocked! now i ride carbon????

i'm here coz i ride...

100%

No, it does NOT 'keep' rotating, it eventually stops.
Now you go and do it, but take your little pinky finger(a much smaller muscle than your hip flexor), and give it a little help on the upstroke each time. What happens now? NOW it keeps going! And no matter where you apply that extra pressure in the 360degrees, the rotation continues, whether it is extra pressure on the downstroke OR the upstroke.
Alternately, get a bike and do a track stand with the cranks horizontal..............bike stays still right. Now do it and take the back foot off the pedal while you are doing it. WOW.......forward motion when the counter weight from the back is removed!

It's not more efficient using the hip flexor than using the Quad, but using both together will be.
You are ADDING a muscle to do any amount of work, big or small, it is going to reduce the amount of work required by the other muscle. Simple physics.

The ratio of the energy delivered by a machine to the energy supplied for its operation. SO??
Why?????


This is true, provided you only want to build the same type of bridges as everyone else! Boring

__________________
When I started steel sucked! Then Alloy rocked! Then Alloy sucked! Then carbon rocked! Then carbon sucked! Then Steel rocked! now i ride carbon????

i'm here coz i ride...

patch70

Blame it on our cerebellum. It's just the way it happens. If you read a neuroscience textbook, it will explain it in way too much detail but you will end up extremely bored.
If downstroke power = 100% with 0% upstroke power,
then,
downstroke power = 85% with 10% upstroke power.
Total power = 95%.

100%

Again, I'm not a neurologist so this is just my thoughts. If that is controlled by the brain then I would expect it can be taught to do what you want, just like most other parts of the brain and the body can be.

__________________
When I started steel sucked! Then Alloy rocked! Then Alloy sucked! Then carbon rocked! Then carbon sucked! Then Steel rocked! now i ride carbon????

i'm here coz i ride...

Roadie_scum

Honestly Ric,

I am amazed at your patience. If I'd been subjected to the derision and abuse that's hit you in this forum I would have either

(i) hunted down and said nasty things to the said derisors
(ii) hunted them down, raced them, beaten them and laughed in their faces
(iii) stopped contributing my expertise to the forum

I think a lot of the confusion comes from mixing 'first principles' arguments with verifiable sports science. The truth doesn't make sense unless you have an intimate understanding of what's happening physiologically, rather than physically or mechanically.

Finally, you mentioned efficiency somewhere in this forum, so I might bring it up here. Can you explain to me how a lower level of O2 consumption at a given power equates with efficiency, using the definition of thermodynamic efficiency you supplied? It seems to me that lower O2 use means just that, but that it doesn't correlate perfectly with energy use which is going to be the same, but made up by anaerobic energy systems. I'm sure your right, but if you could help me understand would be much appreciated (like your intelligent contributions to this forum are by most of us - ignore the vocal minority!).

Roadie.

ric_stern/RST

and all i was trying to do was help and offer some advice!!



not sure if this is the sort of answer you're looking for or something else. pretty sure the this makes sense, but it may not... off to stick my head in a bucket of ice. it's too hot here!

efficiency is defined as the actual mechanical work accomplished divided by energy input and then multiplied by 100.

O2 consumption is a measure of energy input, and depending on the respiratory exchange ratio (the ratio of CO2 produced to O2 consumed that is measured in expired respiratory gases) each litre of O2 means a differing amount of energy has been liberated.

thus as exercise intensity goes up, so does RER and O2 consumed, reflecting that more energy has been liberated. and reflects steady state efforts

not sure if that answers your query?

ric

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beerco

Ahh grasshopper. Do not try and change subjects... your original statement was: "If you apply NO pressure to the up stroke, the opposite leg requires extra force just to push the dead weight(your foot and leg weight on the pedal) through the up stroke."

In an attempt to get the last word in, you're changing the subject to frictional losses. Admit it, you are wrong about the dead weight issue.



Work is work. You as a person still have to do all of it. You haven't explained why exactly it would be better (which it's not) to spread the work between a big muscle group and a little one.

Here's something to chew on: do you think you could TT significantly faster if you could somehow add hand cranks to your TT rig without negatively affecting aerodynamics? (the answer BTW is no)




Nevertheless, if you follow prior art, you can know for sure what won't work.