Model B And Pm3

[old] Spectre · Post by **[old] Spectre** » January 17th, 2006, 3:28 am

Has anyone switched over to a PM3 for their "B". I have had this machine since I was 16 (I am 35 now) and hate to part with a working erg if I can just update the PM. The erg itself works great I am just tired of rolling over at 9999 ms. Does the mount allow you to tilt the PM like on the "C" and "D"? <br /><br />Thanks<br /><br />

[old] c2jonw · Post by **[old] c2jonw** » January 17th, 2006, 9:22 am

Spectre, The PM3 B retrofit includes a short bracket that attaches to the cage and it does allow some tilting of the monitor. It does not, however, include the long monitor arm. JonW @ C2<br /><br /><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Spectre @ Jan 17 2006, 07:28 AM)</b></div></td></tr><tr><td class='quote'>Has anyone switched over to a PM3 for their "B". I have had this machine since I was 16 (I am 35 now) and hate to part with a working erg if I can just update the PM. The erg itself works great I am just tired of rolling over at 9999 ms. Does the mount allow you to tilt the PM like on the "C" and "D"? <br /><br />Thanks <br /> </td></tr></table><br />

[old] John Rupp · Post by **[old] John Rupp** » January 17th, 2006, 5:53 pm

[old] Spectre · Post by **[old] Spectre** » January 18th, 2006, 12:42 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(John Rupp @ Jan 17 2006, 04:53 PM)</b></div></td></tr><tr><td class='quote'>Here are some pictures of my model B, which has an arm for the monitor.<br /><br /><br /> </td></tr></table><br /><br />John, thanks for the pics. Are you happy with the conversion? Any problems etc? The price of a PM 3 is a lot cheaper than a new erg. I like the Model C I use at the club but the seat on the old "B" is so much better.

[old] John Rupp · Post by **[old] John Rupp** » January 18th, 2006, 2:11 am

Hi Charles,<br /><br />You're quite welcome. <br /><br />I am happy with the conversions that I've made to the model B.<br /><br />These have included changing to a 14 tooth cogwheel, instead of the small 13 tooth one, and upgrading to a pm2+. This gives me the same drag factors and resistances as on the models C and D. I don't have the pm3, but prefer the pm2+ anyway.<br /><br />If you upgrade to a pm3, be sure to get the 14 tooth cogwheel to go with it.<br />

[old] Spectre · Post by **[old] Spectre** » January 18th, 2006, 1:04 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(John Rupp @ Jan 18 2006, 01:11 AM)</b></div></td></tr><tr><td class='quote'>Hi Charles,<br /><br />You're quite welcome. <br /><br />I am happy with the conversions that I've made to the model B.<br /><br />These have included changing to a 14 tooth cogwheel, instead of the small 13 tooth one, and upgrading to a pm2+. This gives me the same drag factors and resistances as on the models C and D. I don't have the pm3, but prefer the pm2+ anyway.<br /><br />If you upgrade to a pm3, be sure to get the 14 tooth cogwheel to go with it. <br /> </td></tr></table><br /><br />Whats the advantage of the 14 tooth? I have two cogwheels on the machine now I have no Idea how many teeth are on either one. The chain is currently on the one closest to the flywheel. I row at a DF of 140-145 on the "c" at the gym and they both seem fairly similar. Am I missing something?

[old] John Rupp · Post by **[old] John Rupp** » January 18th, 2006, 2:19 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Spectre @ Jan 18 2006, 09:04 AM)</b></div></td></tr><tr><td class='quote'>Whats the advantage of the 14 tooth? I have two cogwheels on the machine now I have no Idea how many teeth are on either one. The chain is currently on the one closest to the flywheel. I row at a DF of 140-145 on the "c" at the gym and they both seem fairly similar. Am I missing something? </td></tr></table><br /><br />You currently have 13 and 15 tooth cogwheels, and are using the one with 15 teeth.<br /><br />There are two advantages of having the 14 tooth cogwheel, in place of the 13 tooth.<br /><br />(1) You will have a straighter line of pull with the chain;<br /><br />(2) For a given drag factor, you'll have the same resistance as DF's on the models C and D.<br /><br />You can get the same resistances without changing the cogwheel, but would need to calculate for comparison with model C and D cogwheels. By the way, if you change the cogwheel then be sure to change the chain too. These are not expensive parts. However, if you get the pm3 you'll want to change them both anyway.<br />

[old] Spectre · Post by **[old] Spectre** » January 19th, 2006, 6:07 pm

If I add a PM3 to my "B" without the 14 tooth cogwheel am I on the same "playing field" as a C or a D? in other words if I set the DF at 140 (my usual setting for a C machine) on my model b with a PM3 upgrade, would my time be the same for the same effort on a new model.

[old] PaulS · Post by **[old] PaulS** » January 19th, 2006, 6:18 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Spectre @ Jan 19 2006, 02:07 PM)</b></div></td></tr><tr><td class='quote'>If I add a PM3 to my "B" without the 14 tooth cogwheel am I on the same "playing field" as a C or a D? in other words if I set the DF at 140 (my usual setting for a C machine) on my model b with a PM3 upgrade, would my time be the same for the same effort on a new model. <br /> </td></tr></table><br /><br />Yes, as far as power production is concerned. However a DF 140 (as displayed on the PM3) will "feel" different when using a 13, 14, or 15 tooth sprocket. Similar "feeling" DFs with the sprocket differences would be 172(15), 140(14), and 114(13).<br /><br />Does that answer your question?

[old] rspenger · Post by **[old] rspenger** » January 19th, 2006, 7:20 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Spectre @ Jan 19 2006, 03:07 PM)</b></div></td></tr><tr><td class='quote'>If I add a PM3 to my "B" without the 14 tooth cogwheel am I on the same "playing field" as a C or a D? in other words if I set the DF at 140 (my usual setting for a C machine) on my model b with a PM3 upgrade, would my time be the same for the same effort on a new model. <br /> </td></tr></table><br /><br />Set a B at DF 140? Lots of luck. The lowest DF (PM3 reading) I can possibly get from my B without additional cage shielding is about 150. That's with the vent completely closed. It is easy enough to add additional shielding to the cage, but without it, you are stuck with some lower limit. I can't be sure that the limit is 150. On one cold morning, it was over 170, so there seems to be atmospheric effects involved and I have never checked with C2 to see if this is to be expected. Note: I live at an altitude of 4000 ft and would expect that the DF reading would be on the low side due to the lower air density. In that case, the lowest DF limit at sea level may well be considerably higher than 150<br /><br />regards,<br /><br />Bob S.<br /><br />P. S. to C2: Any professional comments about temperature and pressure effects on the DF reading?

[old] Spectre · Post by **[old] Spectre** » January 19th, 2006, 7:28 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(PaulS @ Jan 19 2006, 05:18 PM)</b></div></td></tr><tr><td class='quote'><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Spectre @ Jan 19 2006, 02:07 PM)</b></div></td></tr><tr><td class='quote'>If I add a PM3 to my "B" without the 14 tooth cogwheel am I on the same "playing field" as a C or a D? in other words if I set the DF at 140 (my usual setting for a C machine) on my model b with a PM3 upgrade, would my time be the same for the same effort on a new model. <br /> </td></tr></table><br /><br />Yes, as far as power production is concerned. However a DF 140 (as displayed on the PM3) will "feel" different when using a 13, 14, or 15 tooth sprocket. Similar "feeling" DFs with the sprocket differences would be 172(15), 140(14), and 114(13).<br /><br />Does that answer your question? <br /> </td></tr></table><br /><br />Yes that makes sense. thanks

[old] John Rupp · Post by **[old] John Rupp** » January 19th, 2006, 7:30 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Spectre @ Jan 19 2006, 02:07 PM)</b></div></td></tr><tr><td class='quote'>If I add a PM3 to my "B" without the 14 tooth cogwheel am I on the same "playing field" as a C or a D? </td></tr></table><br />Yes, it is exactly the same.<br /><br /><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'>in other words if I set the DF at 140 (my usual setting for a C machine) on my model b with a PM3 upgrade, would my time be the same for the same effort on a new model. </td></tr></table><br />Yes, your time will be the same, but the resistance will be different.<br /><br />The resistance is determined by the cube of the speed of the flywheel. As I posted on the forum a few years ago, this can be determined by cubing the number of teeth on the cogwheel and thus determining the ratios between drag factors.<br /><br />13 x 13 x 13 = 2197<br />14 x 14 x 14 = 2744<br />15 x 15 x 15 = 3375<br /><br />2197 / 2744 = 0.80<br />2744 / 3375 = 1.23<br /><br />Your 140 drag factor on the 15 tooth cogwheel is the same "resistance" <br />as a drag factor of 114 on a model C or D. [ 140 / 1.23 = 114 ]

[old] Spectre · Post by **[old] Spectre** » January 19th, 2006, 7:40 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(rspenger @ Jan 19 2006, 06:20 PM)</b></div></td></tr><tr><td class='quote'><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Spectre @ Jan 19 2006, 03:07 PM)</b></div></td></tr><tr><td class='quote'>If I add a PM3 to my "B" without the 14 tooth cogwheel am I on the same "playing field" as a C or a D? in other words if I set the DF at 140 (my usual setting for a C machine) on my model b with a PM3 upgrade, would my time be the same for the same effort on a new model. <br /> </td></tr></table><br /><br />Set a B at DF 140? Lots of luck. The lowest DF (PM3 reading) I can possibly get from my B without additional cage shielding is about 150. That's with the vent completely closed. It is easy enough to add additional shielding to the cage, but without it, you are stuck with some lower limit. I can't be sure that the limit is 150. On one cold morning, it was over 170, so there seems to be atmospheric effects involved and I have never checked with C2 to see if this is to be expected. Note: I live at an altitude of 4000 ft and would expect that the DF reading would be on the low side due to the lower air density. In that case, the lowest DF limit at sea level may well be considerably higher than 150<br /><br />regards,<br /><br />Bob S.<br /><br />P. S. to C2: Any professional comments about temperature and pressure effects on the DF reading? <br /> </td></tr></table><br /><br />I dont know what the actual DF on my B machine is. I am just going by feel against the C machine at the club that I know is set at a DF of 140. I have my model B set up in my basement and when it gets hot I have an industrial fan I turn on, the wind from the fan increases the drag quite a bit ( or so it feels to me). I live in Oregon so heat is not generally an issue though. <br />

[old] John Rupp · Post by **[old] John Rupp** » January 19th, 2006, 8:00 pm

Charles,<br /><br />As long as the feel is the same then the drag factor should be quite similar.<br /><br />You can get a similar range of drag factors by adding a speed ring to the side.<br /><br />Black roofing paper is easy to use and you can attach it with plastic ties.<br /><br /><a href='http://i2.photobucket.com/albums/y41/jo ... itorb5.jpg' target='_blank'>http://i2.photobucket.com/albums/y41/jo ... jpg</a><br /><br />I used the black roofing paper first, then replaced it with rubber from a truck tire innertube.

[old] c2jonw · Post by **[old] c2jonw** » January 19th, 2006, 10:04 pm

<br />P. S. to C2: Any professional comments about temperature and pressure effects on the DF reading? <br />[/quote]<br /><br />Hi BobS, Increased air temperature and lower air pressure (as a result of elevation or weather conditions) will have the same effect on drag factor as closing the damper down. DF is a numerical representation of how quickly the flywheel is decelerating. The quicker the deceleration, the bigger the DF.....JonW<br />

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