Concept2 Forum

A question for all the Math majors out there. Drag Factors #'s (90 -230) Damper setting 1 - 10 I reviewed the "Phyicis for Ergometers" but walked away with more questions than answers. <br /><br />Is the Drag Factor that C2 displays on the monitor a useful #. i.e. if you have the Damper set for a drag factor of 100 and you change it to 200, does that mean that you are now processing twice as much air flow into the fan, ie now = to double the drag on the flywheel? I am trying to better understand the relationship to force applied to the handle (effort) and the Damper (drag factor #) If the Drag factor changes from 100 to 200, does it now require twice the accleration on the handle for a setting of 100 Drag factor verse a setting of 200 Drag factor to obtain the same pace / wattage output.<br /><br />Reason for asking is I was trying to see if you know a persons 2K wattage, SPM rate, could I come up with a formula to optomize what to set the Drag factor to, so one could set the Drag factor to the most optimal setting for a given person .<br /><br />I was trying to see if there is a more scientific approach to obtaining a Drag Factor setting for a given person, other that the trial and error approach.<br /><br />So if we have any Math Majors that can plug in real numbers or show me some numbers to plug in that will help to make any sense of all this. I was just trying to better determine that actual relationship between the Drag factor # C2 displays and how C2 uses this number for their calculations of output power.

I don't know if this will help you but you might take a look at <a href='http://www-atm.physics.ox.ac.uk/rowing/ ... meter.html' target='_blank'> The Physics of Ergometers</a>

C2W,<br /><br />Rowing requires a comfortable pull/recovery ratio with a long stroke, i.e. good technique, and we see this at low to medium drag factors. Many say 130-135 which seems like a 4-. My 1x feels around 150, mostly due I think, to the quick solid catch we get afloat with modern oars and very light boats.<br /><br />If your victims can row already, then if they've not decided, maybe they could do a set of hardish 100m erg tests at all damper settings to see how things are going and choose the DF they like best or best corresponds to the boat they're in. Trial and error is by definition the scientific method; any mathematical model has to be tested, proof of the pudding... <br /><br />Then after a year or so's training in all bands maybe they might be ready for a 2k test. By that time tho' they should have long forgotten the erg and be plying oars. <br /><br />So I think asking first the 2k Watts is putting the cart before the long-suffering horse. In any case it's not a fixed value, the idea of training is to change it.<br /><br />All the df actually does is set the flywheel speed at the catch: df too low and we have to chase the flywheel, too high and the pull is heavy and slow, with possible injury risk. At the right level we get a comfortable ratio with max power transfer. Your oarsmen or women must feel comfortable while working hard, otherwise they'll go and do something else or chuck the coach or stroke in the drink. <br /><br />DF is not needed in Watt calculations, for the power all we need is times and flywheel speeds and inertia.

Jamesg, Thank you for taking the time to reply. I was looking more for a better understanding of the erg, and not so much as how to use the erg for better simulation of training for on water. I know that is what the main intent for the erg is to better train the oarsmen in the off season and to help work on timing and technique. I was just more curious on how C2 uses this DF information to calculate the pace that is displayed on the PM2 or PM3 monitors. Mainly to see if I could come up with a formula for optomizing the Damper setting for a given person that may just be interested indoor rowing events. How to find the most effective point to maximize output with the least amount of energy expended. I am currently working on coming up with a formula to help to optomize one's 2K SPM rate for a opt. output based mainly on oarsmans 2K wattage and bodyweight. So I wanted to see if I could come up with anything that would help to set an opt. point for where to set the DF as well. <br /><br />If your using the erg for simulating a racing shell setting the DF in the range of 110 - 135 will be for the most part where they will feel the best to train at for fours & eights. Again thank you very much for your input. <br /><br /><br />Cheers,<br /><br />Stephen

C2Wk,<br /><br />I can't quite decide if you are over-complicating or over-simplifying the problem.<br /><br />What is it that you plan on holding constant?<br />The DF does scale as you have suggested, 100 = 0.5 x 200, but with the exponential nature of fluid drag that does not mean that the handle is moving twice as fast at the lower drag. If the Pace and Stroke rate were held constant, ratio would change, and along with that, peak and average handle force. Or you could hold other things constant and work out what would have to change.<br /><br />Good luck.

<!--QuoteBegin-jamesg+Mar 6 2005, 06:52 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(jamesg @ Mar 6 2005, 06:52 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->C2W,<br /><br />Rowing requires a comfortable pull/recovery ratio with a long stroke, i.e. good technique, and we see this at low to medium drag factors. Many say 130-135 which seems like a 4-. My 1x feels around 150, mostly due I think, to the quick solid catch we get afloat with modern oars and very light boats.<br /><br />edit:..<br /><br />All the df actually does is set the flywheel speed at the catch: df too low and we have to chase the flywheel, too high and the pull is heavy and slow, with possible injury risk. At the right level we get a comfortable ratio with max power transfer. Your oarsmen or women must feel comfortable while working hard, otherwise they'll go and do something else or chuck the coach or stroke in the drink. <br /><br />DF is not needed in Watt calculations, for the power all we need is times and flywheel speeds and inertia. <br /> </td></tr></table><br /><br />Jamesq, Thanks for the informative reply. I was going to post a question similar to this topic, however after reading your reply I have an answer.<br />