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Power13 wrote:
sciguy wrote:
devashish_paul wrote:
jet black wrote:
I wonder if a plane could take off from a giant treadmill.

With airflow over the treadmill going faster than aircraft stall speed, then indeed yes, the aircraft can take off and the treadmill can be going at zero mph too!

Back in my younger years I spent many an hour up in the Maine bush debating in what situations was it better to takeoff upstream or down stream on a river with a float plane. One gets "up on the step" of the floats based on their velocity relative to the water but the plane flies off the water due to its air speed and you can't make decent airspeed without being "on the step". So often we would begin a take off headed upstream but down wind, get on the step and make a turn back around and takeoff upwind.

Hugh

I wonder if a float plane could take off from an Endless Pool?

What about a float plane in an endless pool on the deck of an aircraft carrier? Just jack up the water speed of aircraft carrier as high as you can directly into a gale force wind to the point that you exceed the stall speed of the aircraft, and you should be good to go. No need to even spin up the props of the aircraft....it will take off and hover right on top of the endless pool for a moment until it decelerates and hits stall speed and then crashes to the deck of the carrier (so you better turn on the props and generate thrust equivalent to the carrier speed relative to the water after that).

Now we got water in the ocean, water in the endless pool, a sea plane, a carrier deck, motion of the carrier in the x axis (we left out y and z and we left out rho-theta-omega). Can someone ride a Dimond on the carrier deck to see what else happens?
I wrote a really long post disagreeing with this and suddenly realized I think I was wrong.

The super short version - in all cases the Force required to overcome wind resistance is 27.6 N (given certain assumptions about rider CdA)

Force required to overcome rolling resistance (given certain assumptions about rider weight and tires is 2.4 N.

My mistake was then using apparent wind velocity to multiply force to overcome drag, and bike velocity multiplied with rolling force when I should have used bike velocity for both!!

So the answer for 2mph in a 28mph wind is: 26.7 W

for 4mph in 26 mph wind: 54 W

-------------
Ed O'Malley
http://www.motivengines.com
@EdwardOMalley

-------------
Ed O'Malley
http://www.motivengines.com
@EdwardOMalley
Sorry to keep replying to you! I want to do a little thought experiment about power (or not) to keep a bike and rider stationary in a 30 mph wind:

Without a force applied, the bike will roll backwards. If the force is applied by a rigid structure and nothing is moving in order to generate the force, then yes, power is 0. But if it is held in place by a human applying force to the pedals, power is definitely required, even though the bike's power meter would read 0 because cadence is 0. Things are moving - your heart is pumping, electrons are flowing through neurons, muscle fibers are contracting...

Think about it as if it were an electric motor, rather than a human, connected to the crank. Just enough current is supplied to the motor to keep it from turning backwards. The power in that case is easy to measure - voltage * current.

Comment? Disagree? Agree?

-------------
Ed O'Malley
http://www.motivengines.com
@EdwardOMalley
RowToTri wrote:
Sorry to keep replying to you! I want to do a little thought experiment about power (or not) to keep a bike and rider stationary in a 30 mph wind:

Without a force applied, the bike will roll backwards. If the force is applied by a rigid structure and nothing is moving in order to generate the force, then yes, power is 0. But if it is held in place by a human applying force to the pedals, power is definitely required, even though the bike's power meter would read 0 because cadence is 0. Things are moving - your heart is pumping, electrons are flowing through neurons, muscle fibers are contracting...

Think about it as if it were an electric motor, rather than a human, connected to the crank. Just enough current is supplied to the motor to keep it from turning backwards. The power in that case is easy to measure - voltage * current.

Comment? Disagree? Agree?

Force is being applied to the pedal, but since it isn't moving, then by definition no power is being "used"...but, in the case of a muscle supplying that force, electro-chemical energy will be "spent"...but, as you say, a rigid link could also easily do the same job.

http://bikeblather.blogspot.com/
Last edited by: Tom A.: Aug 3, 16 7:30
RowToTri wrote:
Sorry to keep replying to you! I want to do a little thought experiment about power (or not) to keep a bike and rider stationary in a 30 mph wind:

Without a force applied, the bike will roll backwards. If the force is applied by a rigid structure and nothing is moving in order to generate the force, then yes, power is 0. But if it is held in place by a human applying force to the pedals, power is definitely required, even though the bike's power meter would read 0 because cadence is 0. Things are moving - your heart is pumping, electrons are flowing through neurons, muscle fibers are contracting...

Think about it as if it were an electric motor, rather than a human, connected to the crank. Just enough current is supplied to the motor to keep it from turning backwards. The power in that case is easy to measure - voltage * current.

Comment? Disagree? Agree?

Tom A wrote:
Force is being applied to the pedal, but since it isn't moving, then by definition no power is being "used"...but, in the case of a muscle supplying that force, electro-chemical energy will be "spent"...but, as you say, a rigid link could also easily do the same job.

In your electrical example, you are correct that there would be a measurable voltage and current and, therefore, electrical power would be going somewhere. However, by definition, as Tom points out, there is no motion and, therefore, no net mechanical power (electrical energy was not converted into kinetic energy and is one bad ass trackstand if the rider could stay that steady!). The electrical power, rather than being converted to mechanical power, is being converted into the torque holding the crank in place for some duration of time (as well as some amount of residual heat).

Equivalently, bringing this back to physiology, the rider doing that bad ass trackstand is burning calories doing it, but no mechanical work is being done (by definition), since none of those calories are being converted into kinetic energy of the machine. All of those calories are going into the holding torque for the duration the the bike is kept from rolling backwards (as well as some amount of residual heat...and various biochemical reactions).

ETA: Interestingly, with a few other parts of the electrical system appropriately specified, if you just connected the motor coil leads together, you could likely achieve the same static condition with no voltage applied because of the fact that no mechanical power is being generated.
Last edited by: Koz: Aug 3, 16 8:47
Koz wrote:
RowToTri wrote:
Sorry to keep replying to you! I want to do a little thought experiment about power (or not) to keep a bike and rider stationary in a 30 mph wind:

Without a force applied, the bike will roll backwards. If the force is applied by a rigid structure and nothing is moving in order to generate the force, then yes, power is 0. But if it is held in place by a human applying force to the pedals, power is definitely required, even though the bike's power meter would read 0 because cadence is 0. Things are moving - your heart is pumping, electrons are flowing through neurons, muscle fibers are contracting...

Think about it as if it were an electric motor, rather than a human, connected to the crank. Just enough current is supplied to the motor to keep it from turning backwards. The power in that case is easy to measure - voltage * current.

Comment? Disagree? Agree?

Tom A wrote:
Force is being applied to the pedal, but since it isn't moving, then by definition no power is being "used"...but, in the case of a muscle supplying that force, electro-chemical energy will be "spent"...but, as you say, a rigid link could also easily do the same job.

In your electrical example, you are correct that there would be a measurable voltage and current and, therefore, electrical power would be going somewhere. However, by definition, as Tom points out, there is no motion and, therefore, no net mechanical power (electrical energy was not converted into kinetic energy and is one bad ass trackstand if the rider could stay that steady!). The electrical power, rather than being converted to mechanical power, is being converted into the torque holding the crank in place for some duration of time (as well as some amount of residual heat).

Equivalently, bringing this back to physiology, the rider doing that bad ass trackstand is burning calories doing it, but no mechanical work is being done (by definition), since none of those calories are being converted into kinetic energy of the machine. All of those calories are going into the holding torque for the duration the the bike is kept from rolling backwards (as well as some amount of residual heat...and various biochemical reactions).

ETA: Interestingly, with a few other parts of the electrical system appropriately specified, if you just connected the motor coil leads together, you could likely achieve the same static condition with no voltage applied because of the fact that no mechanical power is being generated.

Right - I get all of that. If you draw a boundary around a system that ends at the surface of the pedal no power is required. But what if you define the system more broadly? If you go back far enough in the chain, in both the motor and the human element - can you not say mechanical power is required? Back at the power station, a turbine is being turned with steam to create the electrical current required to hold the bike steady. Inside your body, all manner of things are contracting, expanding and pumping to generate the force your feet are applying to the pedals (but all of that is much harder to measure than in the power station). The human experiences this in just the same way he experiences applying mechanical power to the pedals. Even in the case of a solar powered motor, the sun is accelerating particles in its fusion reaction.

Sorry for taking this thread so far off-topic....

-------------
Ed O'Malley
http://www.motivengines.com
@EdwardOMalley
Last edited by: RowToTri: Aug 3, 16 9:04
Speaking of the sun, if you want to get really off topic, let's think about the energy expenditure to do a track stand inside an air conditioned stadium versus outside under said sun...

"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @rappstar | Game Designer @ Zwift

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RowToTri wrote:
Koz wrote:
RowToTri wrote:
Sorry to keep replying to you! I want to do a little thought experiment about power (or not) to keep a bike and rider stationary in a 30 mph wind:

Without a force applied, the bike will roll backwards. If the force is applied by a rigid structure and nothing is moving in order to generate the force, then yes, power is 0. But if it is held in place by a human applying force to the pedals, power is definitely required, even though the bike's power meter would read 0 because cadence is 0. Things are moving - your heart is pumping, electrons are flowing through neurons, muscle fibers are contracting...

Think about it as if it were an electric motor, rather than a human, connected to the crank. Just enough current is supplied to the motor to keep it from turning backwards. The power in that case is easy to measure - voltage * current.

Comment? Disagree? Agree?

Tom A wrote:
Force is being applied to the pedal, but since it isn't moving, then by definition no power is being "used"...but, in the case of a muscle supplying that force, electro-chemical energy will be "spent"...but, as you say, a rigid link could also easily do the same job.

In your electrical example, you are correct that there would be a measurable voltage and current and, therefore, electrical power would be going somewhere. However, by definition, as Tom points out, there is no motion and, therefore, no net mechanical power (electrical energy was not converted into kinetic energy and is one bad ass trackstand if the rider could stay that steady!). The electrical power, rather than being converted to mechanical power, is being converted into the torque holding the crank in place for some duration of time (as well as some amount of residual heat).

Equivalently, bringing this back to physiology, the rider doing that bad ass trackstand is burning calories doing it, but no mechanical work is being done (by definition), since none of those calories are being converted into kinetic energy of the machine. All of those calories are going into the holding torque for the duration the the bike is kept from rolling backwards (as well as some amount of residual heat...and various biochemical reactions).

ETA: Interestingly, with a few other parts of the electrical system appropriately specified, if you just connected the motor coil leads together, you could likely achieve the same static condition with no voltage applied because of the fact that no mechanical power is being generated.

Right - I get all of that. If you draw a boundary around a system that ends at the surface of the pedal no power is required. But what if you define the system more broadly? If you go back far enough in the chain, in both the motor and the human element - can you not say mechanical power is required? Back at the power station, a turbine is being turned with steam to create the electrical current required to hold the bike steady. Inside your body, all manner of things are contracting, expanding and pumping to generate the force your feet are applying to the pedals (but all of that is much harder to measure than in the power station). The human experiences this in just the same way he experiences applying mechanical power to the pedals. Even in the case of a solar powered motor, the sun is accelerating particles in its fusion reaction.

Sorry for taking this thread so far off-topic....

Well...to bring it back around, when we talk about the power required to go a certain speed on a bike (as was being discussed here), we talk about the power input to the pedals, and not the kCals required by the rider to do so, right? ;-)

http://bikeblather.blogspot.com/
and when we employ a little kickstand to hold bike and rider upright, rider exerts no force to pedals anymore(if balancing all weight on saddle and bars with feet dangling) a 30mph wind is not going to move the set up.
Right well the kickstand would be the rigid structure I refer to above. It's more interesting I'd we do not include rigid structures.

-------------
Ed O'Malley
http://www.motivengines.com
@EdwardOMalley
That is how we normally define the system, and when the bike is moving it correlates well to the rider's kCal requirement, subject to their metabolic and mechanical efficiency. But when we discuss a situation that virtually no triathlete ever finds themselves in things get more interesting :)

-------------
Ed O'Malley
http://www.motivengines.com
@EdwardOMalley
Rappstar wrote:
Speaking of the sun, if you want to get really off topic, let's think about the energy expenditure to do a track stand inside an air conditioned stadium versus outside under said sun...

Is the outdoor track stand on a carrier deck with roll pitch and yaw and airflow generated by the carrier's motion? Are there Harriers taking off and landing next to the track stander causing some additional wind yaw angle that he has to counter act? Is she on a Dimond or a P5. Did she miss three drug tests in the leadup to Rio. Is the carrier going to get corroded by the foul water in Rio when it docks in the harbor? Will the deflection of the Dimond beam throw a monkey wrench into all the math to calculate the free body diagram instantaneous forces on the track stander?

Last edited by: SBRcoffee: Aug 3, 16 13:20
If a duck barks at midnight, but the only person there to hear it is a mime, who give a shit! ;)
Grill wrote:
A couple fast testers on this side of the pond were on Falcos last year and have switched to a Trek SC and Giant Trinity TT and they're going no slower. If someone gives me one of these I'll test it against my Plasma, but I already know the Dimond will be slower.

I went from Plasma to Dimond. It's not.

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JayPeeWhy wrote:
Grill wrote:
A couple fast testers on this side of the pond were on Falcos last year and have switched to a Trek SC and Giant Trinity TT and they're going no slower. If someone gives me one of these I'll test it against my Plasma, but I already know the Dimond will be slower.

I went from Plasma to Dimond. It's not.

That's good news. Are you willing to share your test data?
JayPeeWhy wrote:
Grill wrote:
A couple fast testers on this side of the pond were on Falcos last year and have switched to a Trek SC and Giant Trinity TT and they're going no slower. If someone gives me one of these I'll test it against my Plasma, but I already know the Dimond will be slower.

I went from Plasma to Dimond. It's not.

Plasma 3 TT? Do you have tunnel or velodrome data to back that up? What front wheel are you using?
Last edited by: Grill: Aug 3, 16 17:23
PubliusValerius wrote:
JayPeeWhy wrote:
Grill wrote:
A couple fast testers on this side of the pond were on Falcos last year and have switched to a Trek SC and Giant Trinity TT and they're going no slower. If someone gives me one of these I'll test it against my Plasma, but I already know the Dimond will be slower.

I went from Plasma to Dimond. It's not.

That's good news. Are you willing to share your test data?

After you. You stated "I know it will be slower". I didn't think we were testing, just coming up with conclusions.

I loved my Plasma. Still would if I had it.

Arguably the Plasma looks better, I like the look of the Dimond but the Scott looks amazing.

The build on the Plasma is excellent although I had some paint issues and I also had to get it warrantied due to an oversized BB.

The build on the Dimond is very good although I had some paint issues and got it warrantied. It's a beam and a frame .... I am not sure what else about 'build' there is to consider. I have a TriRig Alpha X bar. Shimano Di2 'stuff' and triRig brakes. The brakes could do with being a little more firm but I think it's the cabling through the bars more than anything else as the same brakes were fine prior to me installing the bar.

Both Scott and Dimond warrantied the frame no questions asked. Scott took a while to sort but no complaints from me there.

Dimond's service to their customers is likely unbeatable in the sense that I just don't see how it can get any better. I can text them, Skype them, call them, email them whatever and get hold of them in minutes. Never had a question unanswered. Never had a problem unresolved within an hour or two.

The Dimond wins in handling .... in a straight line or smooth curves. The Plasma wins if you need to be more twitchy, but I never needed to be that intricate. The Dimond is simply balls out smooth and utterly in control. At speed the Plasma was always a slightly stressful experience by comparison. I wouldn't have noticed had I not ridden the Dimond after.

Comfort. No contest. Dimond. No beam wobble, just soaks up a bit of vibration. I added Hed Jet Blacks and 25mm tires and it's so sweet to ride. The Scott was harsh by comparison.

Speed. As Rapp said. The difference between very good frames probably isn't even worth considering. I am faster for the same power (than the Scott) whenever I look and conditions are somewhat even. Downhill I am considerably faster, all the time, every time. Likely due to confidence and handling though. Any speed difference may be bike fit, maybe the new bars.

One thing I preferred about the Scott. The wheel always went straight ahead. The Dimond has a tendancy to flop to one side if I walk it by folding the saddle. That may be the centre cabling out of the bars though. I think we're starting to split hairs now.

Paint schemes. Love the Scott's. Some of the Dimond's hurt my eyes but they're what the client wanted so .... I would like to see some really good standard paint schemes to choose from. I went with plain blue.

All subjective points, no testing. I have had a Dimond for over a year now.

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Last edited by: JayPeeWhy: Aug 3, 16 17:29
Grill wrote:
JayPeeWhy wrote:
Grill wrote:
A couple fast testers on this side of the pond were on Falcos last year and have switched to a Trek SC and Giant Trinity TT and they're going no slower. If someone gives me one of these I'll test it against my Plasma, but I already know the Dimond will be slower.

I went from Plasma to Dimond. It's not.

Plasma 3 TT? Do you have tunnel or velodrome data to back that up? What front wheel are you using?

I was being flippant. See post above. It was a Plasma 3 Premium.

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Last edited by: JayPeeWhy: Aug 3, 16 17:31
So different bars, still don't know which Plasma or its specs, and there's no data to support either.

As I've said I have a massive amount of data on my bike and what works with it, as well as many others, so my ascertain that mine is faster with everything else being equal is hardly baseless. I'm testing again come November so if you want to send me your Dimond I'll happily tell you what's what. As I've said, there are faster frames than mine, but the investment needed to get them there is untenable.
Grill wrote:
so my ascertain that mine is faster with everything else being equal is hardly baseless.

Kind of is, a bit. Which was my point.

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Last edited by: JayPeeWhy: Aug 3, 16 17:42
JayPeeWhy wrote:
All subjective points, no testing.

That was a lot of prologue for five words of substance.
JayPeeWhy wrote:
Grill wrote:
so my ascertain that mine is faster with everything else being equal is hardly baseless.

Kind of is a bit. Which was my point.

How? I have seen many of my peers change to 'superior' frames and post higher CdAs. Read my earlier posts, I've seen almost 20w swings between different front wheels in my bike just to see those reversed when tested in another. The fact that I know every part of my bike has been chosen and tested to work together in order to see the lowest CdA possible allows me to deductively reason that the likelihood that the chance these will work as well on the Dimond to be incredibly small.

If you find that to be baseless then you're free to scoff at my claim and continue to use your butt dyno to evaluate your equipment choices.
PubliusValerius wrote:
JayPeeWhy wrote:
All subjective points, no testing.

That was a lot of prologue for five words of substance.

Which is a higher percentage than your paragraph.

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I get it -- the pull of confirmation bias is strong when you have invested this much time and money into a bicycle that is no better than the one you had before it.

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