KK trainer power output for additional flywheel??



millzebub

New Member
Jul 5, 2007
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Hello all. I got a chart from these forums which calculated power for mph on the KK trainer a little while ago.( I believe from wiredued) I have a friend who is going to get an additional flywheel for added resistance. Is there anyone out there who can recalculate the KK numbers for an additional 10-15 lbs of resistance that the flywheel provides? Would it just be a percentage estimation? anybody?? thanks.
 

frenchyge

New Member
Apr 3, 2005
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Adding weight to the existing flywheel should not change the resistance curve of the unit.
 

millzebub

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Jul 5, 2007
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frenchyge said:
Adding weight to the existing flywheel should not change the resistance curve of the unit.
Ok. So the weight is attached to the existing flywheel, huh? I had it wrong there:confused: duhhh...Well, none the less, that is good. No new calculations needed! Great!! Thanks!!:D
 

millzebub

New Member
Jul 5, 2007
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millzebub said:
Ok. So the weight is attached to the existing flywheel, huh? I had it wrong there:confused: duhhh...Well, none the less, that is good. No new calculations needed! Great!! Thanks!!:D
ok. After thinking on this, which may be the problem:) I am confused. If you add weight to the flywheel, you need more power to attain the same mph you would achieve without it, right? Shouldn't that change the mph readings and the power output that corresponds with it?
 

wiredued

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Aug 17, 2004
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http://www.kurtkinetic.com/faq.php

"The Pro Machine was designed specifically for use with the extra weight of the optional 12 lb. flywheel. Because of the extra weight, it requires a bigger 16mm shaft (versus the 12mm of the Road Machine) and also the Pro Machine’s 16 mm shaft is threaded to accept the attachment bolt to hold the 12 lb. flywheel in place."

"It’s the fluid chamber alone that provides the resistance and so the resistance does not change, even with the additional 12 lb. flywheel. The extra weight of the 12 lb. flywheel is only designed to make the ride even smoother and to replicate the outdoor road ride. Because the fluid chamber alone provides the resistance, there is no need to recalibrate the Kinetic PC when using either just the 6 lb. permanent flywheel or the additional 12 lb. flywheel."

Formula 5.244820x + .019168x^3

17mph=183.33w
17.1mph=185.53w
17.2mph=187.74w
17.3mph=189.98w
17.4mph=192.23w
17.5mph=194.51w
17.6mph=196.80w
17.7mph=199.12w
17.8mph=201.46w
17.9mph=203.81w
18mph=206.19w
18.1mph=208.59w
18.2mph=211.01w
18.3mph=213.45w
18.4mph=215.91w
18.5mph=218.39w
18.6mph=220.89w
18.7mph=223.42w
18.8mph=225.96w
18.9mph=228.53w
19mph=231.12w
19.1mph=233.73w
19.2mph=236.36w
19.3mph=239.02w
19.4mph=241.70w
19.5mph=244.40w
19.6mph=247.12w
19.7mph=249.86w
19.8mph=252.63w
19.9mph=255.42w
20mph=258.24w
20.1mph=261.07w
20.2mph=263.93w
20.3mph=266.81w
20.4mph=269.72w
20.5mph=272.65w
20.6mph=275.60w
20.7mph=278.58w
20.8mph=281.58w
20.9mph=284.60w
21mph=287.65w
21.1mph=290.72w
21.2mph=293.82w
21.3mph=296.94w
21.4mph=300.09w
21.5mph=303.26w
21.6mph=306.45w
21.7mph=309.67w
21.8mph=312.92w
21.9mph=316.19w
22mph=319.48w
22.1mph=322.80w
22.2mph=326.15w
22.3mph=329.52w
22.4mph=332.92w
22.5mph=336.34w
22.6mph=339.79w
22.7mph=343.26w
22.8mph=346.76w
22.9mph=350.29w
23mph=353.84w
23.1mph=357.42w
23.2mph=361.03w
23.3mph=364.66w
23.4mph=368.32w
23.5mph=372.01w
23.6mph=375.72w
23.7mph=379.46w
23.8mph=383.23w
23.9mph=387.03w
24mph=390.85w
24.1mph=394.70w
24.2mph=398.58w
24.3mph=402.48w
24.4mph=406.42w
24.5mph=410.38w
24.6mph=414.37w
24.7mph=418.39w
24.8mph=422.44w
24.9mph=426.51w
25mph=430.62w
25.1mph=434.75w......Lance Armstrong FTP maybe
25.2mph=438.91w
25.3mph=443.10w
25.4mph=447.32w
25.5mph=451.57w
25.6mph=455.85w
25.7mph=460.16w
25.8mph=464.49w
25.9mph=468.86w
26mph=473.26w


millzebub said:
ok. After thinking on this, which may be the problem:) I am confused. If you add weight to the flywheel, you need more power to attain the same mph you would achieve without it, right? Shouldn't that change the mph readings and the power output that corresponds with it?
 

Ergoman

New Member
Feb 21, 2007
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The numbers you list below match the table provided on the Kurt Kinetic website, but don't seem to match the formula. For example, I get 185.84 watts when I use the formula for 17 mph. Which do you suppose is correct?

wiredued said:
http://www.kurtkinetic.com/faq.php

"The Pro Machine was designed specifically for use with the extra weight of the optional 12 lb. flywheel. Because of the extra weight, it requires a bigger 16mm shaft (versus the 12mm of the Road Machine) and also the Pro Machine’s 16 mm shaft is threaded to accept the attachment bolt to hold the 12 lb. flywheel in place."

"It’s the fluid chamber alone that provides the resistance and so the resistance does not change, even with the additional 12 lb. flywheel. The extra weight of the 12 lb. flywheel is only designed to make the ride even smoother and to replicate the outdoor road ride. Because the fluid chamber alone provides the resistance, there is no need to recalibrate the Kinetic PC when using either just the 6 lb. permanent flywheel or the additional 12 lb. flywheel."

Formula 5.244820x + .019168x^3

17mph=183.33w
17.1mph=185.53w
17.2mph=187.74w
17.3mph=189.98w
17.4mph=192.23w
17.5mph=194.51w
17.6mph=196.80w
17.7mph=199.12w
17.8mph=201.46w
17.9mph=203.81w
18mph=206.19w
18.1mph=208.59w
18.2mph=211.01w
18.3mph=213.45w
18.4mph=215.91w
18.5mph=218.39w
18.6mph=220.89w
18.7mph=223.42w
18.8mph=225.96w
18.9mph=228.53w
19mph=231.12w
19.1mph=233.73w
19.2mph=236.36w
19.3mph=239.02w
19.4mph=241.70w
19.5mph=244.40w
19.6mph=247.12w
19.7mph=249.86w
19.8mph=252.63w
19.9mph=255.42w
20mph=258.24w
20.1mph=261.07w
20.2mph=263.93w
20.3mph=266.81w
20.4mph=269.72w
20.5mph=272.65w
20.6mph=275.60w
20.7mph=278.58w
20.8mph=281.58w
20.9mph=284.60w
21mph=287.65w
21.1mph=290.72w
21.2mph=293.82w
21.3mph=296.94w
21.4mph=300.09w
21.5mph=303.26w
21.6mph=306.45w
21.7mph=309.67w
21.8mph=312.92w
21.9mph=316.19w
22mph=319.48w
22.1mph=322.80w
22.2mph=326.15w
22.3mph=329.52w
22.4mph=332.92w
22.5mph=336.34w
22.6mph=339.79w
22.7mph=343.26w
22.8mph=346.76w
22.9mph=350.29w
23mph=353.84w
23.1mph=357.42w
23.2mph=361.03w
23.3mph=364.66w
23.4mph=368.32w
23.5mph=372.01w
23.6mph=375.72w
23.7mph=379.46w
23.8mph=383.23w
23.9mph=387.03w
24mph=390.85w
24.1mph=394.70w
24.2mph=398.58w
24.3mph=402.48w
24.4mph=406.42w
24.5mph=410.38w
24.6mph=414.37w
24.7mph=418.39w
24.8mph=422.44w
24.9mph=426.51w
25mph=430.62w
25.1mph=434.75w......Lance Armstrong FTP maybe
25.2mph=438.91w
25.3mph=443.10w
25.4mph=447.32w
25.5mph=451.57w
25.6mph=455.85w
25.7mph=460.16w
25.8mph=464.49w
25.9mph=468.86w
26mph=473.26w
 

wiredued

New Member
Aug 17, 2004
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I made the same mistake as you just did some one here corrected me a while back it is a typo on the kinetic site considering the number entered into the computer is .01917 which is very close to .019"1"68 not .01968



Ergoman said:
The numbers you list below match the table provided on the Kurt Kinetic website, but don't seem to match the formula. For example, I get 185.84 watts when I use the formula for 17 mph. Which do you suppose is correct?
 

wiredued

New Member
Aug 17, 2004
1,300
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Sorry I don't know anything about that unit... BTW what is the flywheel weight on the Clydesdale?



jetnjeff said:
Do you have any numbers for the Clydesdale unit. I bought one, but can not even find it on the Kinetic Website. Google only find those for sale. No info.

Looks Identical to the standard. I assume the internals have been changed to simulate a heavier rider.
 

jetnjeff

New Member
Mar 17, 2006
188
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It looks like the same exact size as the standard Road Machine. So barring different materials it is the same.

I like the smaller flywheel cause I have to make my spin smooth. Not the flywheel. I would think the power curve during accelerations and decelerations would be different with different flywheel weights, but same at steady state.

So the heavier flywheel might fell more real during sprints and such for a big guy.

I am not so concerned about that though.


wiredued said:
Sorry I don't know anything about that unit... BTW what is the flywheel weight on the Clydesdale?
 

daveryanwyoming

Well-Known Member
Oct 3, 2006
3,857
190
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millzebub said:
...I am confused. If you add weight to the flywheel, you need more power to attain the same mph you would achieve without it, right? Shouldn't that change the mph readings and the power output that corresponds with it?
Flywheels store energy, they don't increase frictional losses or other energy loss terms the way a fan (air resistance), fluid resistance unit(similar to air resistance but more so) or electrical resistance unit does. Yep, you have to put some energy into accelerating a flywheel but that energy is returned when you coast. At steady state the power required to turn the resistance unit / flywheel combo is the same but smoother than the same system with a smaller or lower mass (really lower moment of inertia) flywheel.

So to answer your questions, the watts vs mph readings from your KK or other trainer won't change with a larger flywheel in ways that you can measure. The larger flywheel will just smooth out the irregularites of your pedal stroke by coasting through the dead spots better. If you could make very fast micro power measurements you'd see it takes additional energy to initially accelerate the larger flywheel but you'd get that energy back by maintaining wheel speed when you coasted saving you the effort of accelerating the system again to make up for the lost speed. In general you won't see these differences during acceleration for reasonably sized flywheels because the moment of inertia is still relatively small and cyclometers and power meters only sample so often and usually average their displays a bit to reduce erratic readings. IOW the additonal moment of inertia is small enough that you still acellerate the trainer fairly fast and the averaging/sampling rate of the cycling computers make it hard to see the micro differences during that period of acceleration.

-Dave