Proper technique

[PaulS]

Paul, you never responded to my question here:

You have discovered a possible serious problem with the PM3 and with the verification code. It sounds like you were rowing at effectively 0 drag. Does anyone know if you can get a verification code under those circumstances, or will the PM3 accept any drag setting? John for example has modified his C2 pretty considerably to row at super low drag settings, but I always assumed that the PM3 adjusted for that (the assumption of our sport is that the PM3 adjusts for diffences in drag "perfectly").

Is wrapping your C2 fan cage in plastic another secret method to cheat the PM3? Why can't it sense drag that is effectively=0 and/or how does ultra low drag mess up the mathematics involved. I would have thought that lowering drag to 0 would have reduced the credit for watts produced to 0 as well.

Sorry about that, I thought I did reply with the basic information. The C2 PM's do go into an error condition if the DF is too low. I can't recall the exact number right now, but it's something around 45. Any DF above 45 will be fine as far as the accuracy of the PM's power calculating goes. I hadn't observed, nor had I even attempted to observe, this phenomena on the PM3/PM4 devices, but it seems that they will produce errors in Stroke rate that make the "defect" obvious.

I really don't know what the error handling is for the PM's, that would be a question for the guys at C2 to address if they want to. Your assumption that as the DF approaches 0 so would the power production required to maintain flywheel speed, yielding slower and slower paces, but at some point the error handling code "thinks" the DF is High instead of Low and creates what we are seeing.

[Nosmo]

but at some point the error handling code "thinks" the DF is High instead of Low and creates what we are seeing.

Have had the opposite experience. Was repairing an erg once and rowed without the cage. I think the DF registered as something like 60 but it was really heavy. Don't know what happens to the pace and stroke ratings.

[PaulS]

but at some point the error handling code "thinks" the DF is High instead of Low and creates what we are seeing.

Have had the opposite experience. Was repairing an erg once and rowed without the cage. I think the DF registered as something like 60 but it was really heavy. Don't know what happens to the pace and stroke ratings.

Makes sense in a strange sort of way, the "taped up" condition will display something like 234+ and go whacky, perhaps when the "free flywheel" goes above 23X+ it does the opposite. I've not seen the high end of the desired range on a PM, but I do know that a Model A has a DF in the range of 2000 and in combination with a moment of inertia that is about 5 times the Mod B and up is why it has a whole different set of error handling and valid ranges to deal with. Our first go with ErgMonitor and a Model A gave very strange looking pace values, but we had made any DF above 300 and "error" and considered it to be 200, lucky for us the debugging was easy due to the about a decimal value out, we turned off the error handling and let it calulate it completely and found the real issue right away.

The more you practice, the luckier you get.

[gregory.cook]

I just wrapped the cage in a drop-cloth we use for painting. The drag factor was 300 (exactly) and I managed to row a 2K in 3:56.3 at 27 spm. And it was easy; my HR was probably only 125 at the end. To top it off (this won't surprise anyone at this point) it gave me a verification code.

Edit: Model C / PM3

[michaelb]

thanks guys, I think this issue and the wrong PM monitor setting issue pretty much sink any notion of the PM verification system for now.

It would be fun though to wrap my cage and join an online race with the fast boys. I could hang with the pack for once and then show them how to really sprint down to the finish.

[Bob S.]

Bob, There are decaffeinated brands that are just as tasty as the real thing...

So why the bleep were you on your computer at 4:50 in the morning??

Bob S.

Having some OJ before heading out for a row, checking the lake to make sure it was nice out.

Paul,

I was sort of taken aback by the coffee reference, since (in sharp contrast to my impression of most Seattleites) I am avidly anti-coffee.

Quite some time ago, I came up with the following:

I am not keen on any xanthine.

Alcohol does not enthrall.

Nicotine is downright mean.

Triglycerides will stretch your hides - and likewise all those saccharides.

One should avoid an alkaloid.

Cannabinol? No, not at all.

Use of cocaine will rot your brain.

Please excuse my chemist's perspective. One translation is probably in order. Caffeine is a xanthine derivative, specifically 1,3,7-trimethylxanthine. A couple of others, both of them dimethyl-xanthines, are theobromine (found in chocolate), and theophylline (used to treat asthma). All three increase the pulse rate.

Bob S.

Forumites:

Please excuse my buggering up the thread.

[Nosmo]

thanks guys, I think this issue and the wrong PM monitor setting issue pretty much sink any notion of the PM verification system for now....

There is always a way to defeat the verification code. Anyone with a little electronic skills could come up with a number or ways of feeding pulses in to the PM. Just sample the pulses from a few hard strokes and repeatedly play them back. A cheap signal generator (<$200) could simulate the pulses just fine. It would also be easy and cheap to make an variable oscillator to do it.

People will always find a way to cheat. I'll worry about my own scores and not be too concerned with anyone else's--after all this is about bragging rights on a web site. I'd rather have people cheat by fooling the monitor then using steroids and EPO.

[PaulS]

So why the bleep were you on your computer at 4:50 in the morning??

Bob S.

Having some OJ before heading out for a row, checking the lake to make sure it was nice out.

Paul,

I was sort of taken aback by the coffee reference, since (in sharp contrast to my impression of most Seattleites) I am avidly anti-coffee.

I apologize for the slur.

Near as I can tell, the mention of "junk meters" will have nearly the same beneficial effect of actually rowing them so I will go back to the chemical free method of niggling you. All in good humor my friend.

There is a riddle about alcohol you might appreciate:

How do you get the Varsity Men's 8 drunk?













Toss them a 6 pack....

[TomR]

Forumites:

Please excuse my buggering up the thread.

Those were stirring outbursts, Bob. No apology required.

[HeavyA]

Hey guy's

Just want to make sure I have not adversely effected my PM3 by rowing free for so long. If you could just give me your opinion.

500m-1:52-DF138-s/m40. Approximately 7m a stroke. Meters per stroke is the same no matter what the drag factor.


Thanks Jeff

[PaulS]

Hey guy's

Just want to make sure I have not adversely effected my PM3 by rowing free for so long. If you could just give me your opinion.

500m-1:52-DF138-s/m40. Approximately 7m a stroke. Meters per stroke is the same no matter what the drag factor.


Thanks Jeff

Stroke rate is pretty high for a 1:52, do what you can to increase the Distance Per Stroke (DPS), perhaps beginning with about 10. and also lower the DF to the range of 110 or so. How far are you goingg at 1:52 R40? (and just to make sure, are you really taking 40 strokes a minute according to an independent clock?)

The PM3 can be reset by removing the batteries for 60 minutes or pressing the reset button through the pinhole on the back of the unit. May be worth a try if you are getting strange readings.

[Citroen]

I really don't know what the error handling is for the PM's, that would be a question for the guys at C2 to address if they want to. Your assumption that as the DF approaches 0 so would the power production required to maintain flywheel speed, yielding slower and slower paces, but at some point the error handling code "thinks" the DF is High instead of Low and creates what we are seeing.

There's lots of integer maths (using scale/precision to work in tenths of seconds) in the PM3/PM4 and LogCard. That tends not to handle values that approach zero in a sensible way. Floating point maths costs more in processor time and memory.

Remember the PM3 is now a five year old device. Look at how much your cell phone has changed in that same period.

The PM4s are much more capable so we may see improvements (if we pester Scott) in this area.

[Nosmo]

The PM4s are much more capable so we may see improvements (if we pester Scott) in this area.

"In this area"? when people are rowing with a DF approaching zero?

Snark aside, doesn't seem like it would be a big priority for them.

[Citroen]

The PM4s are much more capable so we may see improvements (if we pester Scott) in this area.

"In this area"? when people are rowing with a DF approaching zero?

Snark aside, doesn't seem like it would be a big priority for them.

It might be for John Rupp - he's always mentioning covering his erg with strange objects to reduce drag below the sensible minimum.

There are other feechurs in the realm of weird PM3/PM4 maths that would be higher up my wish list. (That's one of the reasons why I'm a very willing beta tester for PM3/PM4 firmware - it gives me a direct line to Scott and his developers.)

[Bob S.]

Having some OJ before heading out for a row, checking the lake to make sure it was nice out.

Paul,

I was sort of taken aback by the coffee reference, since (in sharp contrast to my impression of most Seattleites) I am avidly anti-coffee.

I apologize for the slur.

Near as I can tell, the mention of "junk meters" will have nearly the same beneficial effect of actually rowing them so I will go back to the chemical free method of niggling you. All in good humor my friend.

There is a riddle about alcohol you might appreciate:

How do you get the Varsity Men's 8 drunk?

Toss them a 6 pack....

I didn't want to continue to hijack this thread, so I sent a response to this message under a new thread, "Slurs and Responses."

Bob S.