Drag Factors

[old] John Rupp · Post by **[old] John Rupp** » July 21st, 2004, 10:38 pm

Most rowers would use a much higher drag factor setting for a sprint, than they would for a marathon. Sprints take maximum acceleration, whereas distance events keep acceleration to a minimum. I plotted my PB drag factors with speed, and found a very close correlation. In line with my own PB's, I used Eskild Ebbesen's 117 drag factor at 1:30.8 pace for a data point, along with a 65 drag factor at 2:24 pace. This curve showed an average of only 5 deviations over 14 of my PB's, from 500 meters through the marathon. Considering drag factors are mechanically dependent only on fan resistance and pace, here is a chart of this relationship: pace - drag factor 2:32 ----- 61 2:24 ----- 65 2:16 ----- 70 2:08 ----- 76 2:00 ----- 82 1:52 ----- 90 1:44 ----- 98 1:36 ---- 109 1:28 ---- 122 1:20 ---- 137 1:12 ---- 157 1:04 ---- 183

[old] rowsteve · Post by **[old] rowsteve** » July 23rd, 2004, 7:02 pm

John, Since I am new to all of this, do I understand your comments correctly to mean that a higher damper setting is better for improving sprint times, and a lower one better for distance? Also, how does one calculate drag factor? Thanks. Steve Sohinki

[old] John Rupp · Post by **[old] John Rupp** » July 23rd, 2004, 9:18 pm

Steve, Yes, that's right. You can find the drag factor with the Pm2, by pressing [ok][rest] at the same time and then rowing. The drag factor shows up in the lower right corner.

[old] PaulS · Post by **[old] PaulS** » July 23rd, 2004, 11:53 pm

</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE (rowsteve @ Jul 23 2004, 11:02 PM)</td></tr><tr><td class='quote'> Since I am new to all of this, do I understand your comments correctly to mean that a higher damper setting is better for improving sprint times, and a lower one better for distance? Also, how does one calculate drag factor? Thanks. Steve Sohinki  </td></tr></table> Hi Steve, This thread was being ignored for good reasons, that may or may not become apparent shortly, but the answer to your question is "No, the Drag Factor can not be described as 'better' in relation to the distance involved." It has to do with training yourself to work with whatever drag factor you end up deciding on (100-150 will suit 90%+ of folks). Many tend to think they are getting better paces when at high DF's before they figure out the proper technique, but the same average power input is required for a given pace, regardless of DF. And though it may feel like you can produce more handle force at a high DF, as you become trained to coordinate your effort well, producing high force at high speed (High power) will follow. Take it slow and get the technique down, it makes for less bad habits to overcome later. Erg on, Paul Smith

[old] Canoeist · Post by **[old] Canoeist** » July 24th, 2004, 11:40 pm

I was experimenting with the PM3 force vs distance graphing function yesterday. My stroke at damper #10 looks much different from my stroke at damper #1. At #10, the graph looks like a mound with the highest point in the center. As the damper is lowered, the peak of the mound moves to the the left. By the time I get down to damper #1, the graph looks much more like a triangle - max force comes very quickly, but decays steadily. The total area under the curve looks small too. I find it easiest to row at a 135 drag factor. (#3) The graph at this setting looks like a plateau with sloping sides. I agree that drag factor does make a difference. Finding the drag factor that maximizes the area under the force curve is the key to efficincy. Probably the most efficient drag for a sprint is not the same as for a marathon. But, I doubt that they are different by more than two damper settings. Cheers, Paul Flack

[old] John Rupp · Post by **[old] John Rupp** » July 25th, 2004, 1:19 am

Paul, What drag factor did you use for your fastest max split and what do you use for the marathon. I agree it is possible to use the same drag factor for all distances, many rowers do this and I have too. My fastest times though, from max split through the marathon, have come with a wide range of drag factors. A note on the curve: I've taken the X and the Y axis' down to 1 and am surprised how well the curve holds true all the way. This chart is useful even though the rower's times are above or below it. For example the best curve for me might well be about 5% below the chart. Other rowers might be 5 or 10% above it. However the same percentage deviation would hold true for all events for that rower, and this is easy to calculate from the chart.

[old] John Rupp · Post by **[old] John Rupp** » July 25th, 2004, 1:27 am

</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE (Canoeist @ Jul 24 2004, 08:40 PM)</td></tr><tr><td class='quote'>My stroke at damper #10 looks much different from my stroke at damper #1.  </td></tr></table> There's a wide range of drag factors between #1 and #10. From the chart this is consistent with a wide range of speeds. Did you vary the speeds with the drag factors? Try matching the drag factors to the speeds on the chart, or drag factors 10% above them, and see if the force curves are closer together. I find my stroke stays virtually identical from 200 meters through the marathon, and even for "all day pace", with the variation of drag factors from the chart. That would not be possible if the drag factor was the same for all distances.

[old] Carl Henrik · Post by **[old] Carl Henrik** » July 25th, 2004, 3:05 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE </td></tr><tr><td class='quote'>Considering drag factors are mechanically dependent only on fan resistance and pace, here is a chart of this relationship: </td></tr></table> I believe this is actually wrong. Drag factor should only be dependent on fan resistance, however, I have noted a very small dependence on pace (on some machines at least). The DF may be 1 or 2 lower when putting in extremely low wattage (100w). Also when sprinting (as in 100m) a high DF is preferable so that one can catch the fan at the... catch . A high DF leads to muscle fatigue though so it has no place in endurance events, where it also is easier to "catch at the catch".

[old] Canoeist · Post by **[old] Canoeist** » July 25th, 2004, 8:24 am

When I was experimenting with the PM3 force curves, I rowed about 500m at a 1:45 pace at different damper settings. I could do this fairly easily at each damper setting. But, it felt like I had to work harder when the damper was on #1. Then I did some 250m pulls at close to maximum output (1:22 pace) at the different damper settings. With the damper set on #1, I couldn't get my pace down to 1:22. The curve dropped off too quickly to get enough area under the curve. Higher damper settings were OK because the force curves were flatter. Paul Flack

[old] Canoeist · Post by **[old] Canoeist** » July 25th, 2004, 8:33 am

</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE (John Rupp @ Jul 22 2004, 02:38 AM)</td></tr><tr><td class='quote'>pace - drag factor 1:20 ---- 137 1:12 ---- 157 1:04 ---- 183  </td></tr></table> John, I am afraid that I am not strong enough to explore this part of the force curve. I have a bit of a problem going below a 1:20 pace at any drag factor. How long can you go at the 1:12 pace? The 1:04 pace? Cheers, Paul Flack

[old] John Rupp · Post by **[old] John Rupp** » July 25th, 2004, 3:17 pm

</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE (Carl Henrik @ Jul 25 2004, 12:05 AM)</td></tr><tr><td class='quote'> Drag factor should only be dependent on fan resistance, however, I have noted a very small dependence on pace  </td></tr></table> Carl, Yes dependent on fan resistance. Thus the faster the pace, the greater the resistance. What drag factor do you use for max split, and what drag factor do you use for the marathon?

[old] John Rupp · Post by **[old] John Rupp** » July 25th, 2004, 3:29 pm

</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE (Canoeist @ Jul 25 2004, 05:33 AM)</td></tr><tr><td class='quote'>John, I am afraid that I am not strong enough to explore this part of the force curve. I have a bit of a problem going below a 1:20 pace at any drag factor. How long can you go at the 1:12 pace? The 1:04 pace? </td></tr></table> Paul, Not very long! My fastest max split is 1:24 pace, with a very high 190-200 drag factor, 1:28 with a df of 100, and 1:29 with a df of 88. The chart shows a 135 df for 1:24 pace, which should be plenty high enough. I believe Graham Benton did his 1:04 with a df of 170. Those who were there could confirm.

[old] Carl Henrik · Post by **[old] Carl Henrik** » July 25th, 2004, 4:11 pm

Paul, that's interesting about the shape of the curve and area under it at damper setting 1. It may wrongly be interpreted as that it is much harder to put power through the handle when DF is low (small area), especially with the arms, but easier to get the high pressure with the legs quickly. This would be the opposite to what I said about it being hard to catch up with the flywheel. There is no paradox here though. The curve is drawn with respect to force and time (that would explain it). At a small DF the flywheel gets a huge acceleration and the time to complete a stroke will be small. If you keep the same force on the handle as with a higher DF, the area under the curve will be less, due to that you pull for a shorter time. (Energy = power*time) The triangular shape is due to the faster acceleration with a low DF as well. When the handle moves quickly instead of slower as with a higher DF, the power, that is Force*speed, remains constant if there is a quickly descending force and a quickly ascending speed. The power may therefore be the same when engaging arms and legs, despite the "intuitive" feel that this is not so. This corresponds to the more even curve at higher DF where a less increasing speed makes for a less decreasing force and a gentler slope. In conclusion: A small DF means shorter and more frequent bursts of force and higher speeds on the handle and rower. Too small a DF and accelerating the rower (yourself) back and forth will be a hindrance (both directions to keep the stroke/recovery ratio). To large a DF and you muscles will be fatigued from "not getting their way", as well as at the same stroke recovery ratio you will have more of a oscillation around average speed wich means loosing energy.

[old] Carl Henrik · Post by **[old] Carl Henrik** » July 25th, 2004, 4:29 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE </td></tr><tr><td class='quote'>Carl, Yes dependent on fan resistance. Thus the faster the pace, the greater the resistance. </td></tr></table> I was suspecting an anwser like that. One may write DF = f(pace, resistance) or pace=g(DF,resistance) or resistance=h(DF,pace) to calculate any of the three above. however, when sitting on the erg there is only one thing the DF can be changed with, that is by changing the damper setting wich is the same as altering the resistance for the fan at all non zero paces. Pulling harder on the chain and increasing you pace won't change DF. In that respect, DF in only dependent on fan resistance, or damper setting if you will

[old] John Rupp · Post by **[old] John Rupp** » July 25th, 2004, 6:27 pm

</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE (Carl Henrik @ Jul 25 2004, 01:29 PM)</td></tr><tr><td class='quote'> there is only one thing the DF can be changed with, that is by changing the damper setting Pulling harder on the chain and increasing you pace won't change DF  </td></tr></table> Exactly. You change the drag factor by changing the setting. Also, there is no resistance unless the fan is moving, regardless of the drag factor. For a given DF, the faster the pace, the higher the resistance.

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