Dynamic vs Stationary

[johnlvs2run]

I am now completing my third month of Dynamic use. It took me about three months to transition from static to slides. So I am nearing the term that I gave myself to be able to say something solid concerning the difference. I think the Dynamic is much harder to hold a load over a longer period. I still attribute this to having the muscles (legs and glut) work differently (harder) compared with either the slides or static which allowed me to throw more inertia into the compression and lay back of the finish with each giving me a little more length compared with the Dynamic. I am finding that an additional four to five strokes per minute is required to equal my static performance over the long term, greater than 30 minutes. Maybe this is a strength issue that will eventually go away with more work. I hope so.

Thanks much for that feedback.

I'm curious how the difference will be with different weights.

From your description, the advantage of tossing weight against inertia on the static will not be as great on the dynamic erg. This can be a very good thing, especially if times will be equalized between weights, as they are on the water. Olympic sculling records are identical regardless of weight.

[Ultramega OK]

I am now completing my third month of Dynamic use. It took me about three months to transition from static to slides. So I am nearing the term that I gave myself to be able to say something solid concerning the difference. I think the Dynamic is much harder to hold a load over a longer period. I still attribute this to having the muscles (legs and glut) work differently (harder) compared with either the slides or static which allowed me to throw more inertia into the compression and lay back of the finish with each giving me a little more length compared with the Dynamic. I am finding that an additional four to five strokes per minute is required to equal my static performance over the long term, greater than 30 minutes. Maybe this is a strength issue that will eventually go away with more work. I hope so.

I don't think it is so much as strength issue as an issue of unmeasured energy loss in the mechanism. For lack of a better term the static erg mechanism seems more "direct". I find similar results on my Oartec. 5-10% higher splits at a given heart rate vs the static. For example my best 2k static is about 6:36, on the slider it is 7:00.

[johnlvs2run]

I don't think it is so much as strength issue as an issue of unmeasured energy loss in the mechanism. For lack of a better term the static erg mechanism seems more "direct". I find similar results on my Oartec. 5-10% higher splits at a given heart rate vs the static. For example my best 2k static is about 6:36, on the slider it is 7:00.

That is interesting as I saw a report of 5 seconds faster splits on the slider, though it was quite subjective, being at a similar heart rate. I feel that any relevant comparisons should be like yours, at full speed.

[slwiser]

I don't think it is so much as strength issue as an issue of unmeasured energy loss in the mechanism. For lack of a better term the static erg mechanism seems more "direct". I find similar results on my Oartec. 5-10% higher splits at a given heart rate vs the static. For example my best 2k static is about 6:36, on the slider it is 7:00.

I am not sure that I agree with the conjecture concerning "unmeasured energy loss in the mechanism." I don't see this as being credible. Rowing Biomechanics web site uses measurements and have measured both static, slides and dynamic and has not reported any of this information. If they had observed any I would think this would be a big issue to report such a finding.

[NavigationHazard]

Oddly enough, the current issue of RBN answers a question from Forum regular Ralph Earle regarding 'feel' on an erg. Short story: it's complicated. See http://www.biorow.com/RBN_en_2011_files ... News06.pdf

[johnlvs2run]

Rowing Biomechanics web site uses measurements and have measured both static, slides and dynamic

Would you happen to have a link to their measurements and results.

[slwiser]

Would you happen to have a link to their measurements and results.

Here is one PDF with three ergs and OTW boats measured:
http://www.biorow.com/RBN_en_2011_files ... News01.pdf

[Ultramega OK]

Responding to slwiser:

My basis for mentioning unmeasured losses on my dynamic come from these comments of c2jonw which jibe with my experience on the Oartec compared to the static C2:

We have not observed the use of a Concept2 monitor on an Oartech machine and therefore can not verify any aspect of its use or its compatibility both physically and electronically. We do have serious doubts to the claim of matching the calibration of a C2. The Slider has a number of additional unmeasured energy losses in the system, the most notable being that the chain is run through an idler cog under full load to be able to tuck the flywheel in closer to the rower. The C2 chain goes directly to the flywheel. We tested this type of idler cog system many years ago in an attempt to shorten the machine and discovered that there was a significant energy loss which is not measured by the monitor. C2JonW

[slwiser]

Responding to slwiser:

My basis for mentioning unmeasured losses on my dynamic come from these comments of c2jonw which jibe with my experience on the Oartec compared to the static C2:

Thanks for the clarification that the "unmeasured losses" is associated with the Oartec Slider which I thought you were attributing to both the Slider and Concept Dynamic, my misunderstanding.

[johnlvs2run]

Here is one PDF with three ergs and OTW boats measured:
http://www.biorow.com/RBN_en_2011_files ... News01.pdf

Thanks. I'll take a look at that when my viewer is working again.

[Ultramega OK]

Yeah My experience is only with the Oartec slider as far as dynamics go. I would love to try both the C2 dynamic and the RP indoor sculler but I don't know of any that are nearby.

[johnlvs2run]

Responding to slwiser:

My basis for mentioning unmeasured losses on my dynamic come from these comments of c2jonw which jibe with my experience on the Oartec compared to the static C2

We have not observed the use of a Concept2 monitor on an Oartech machine and therefore can not verify any aspect of its use or its compatibility both physically and electronically. We do have serious doubts to the claim of matching the calibration of a C2. The Slider has a number of additional unmeasured energy losses in the system, the most notable being that the chain is run through an idler cog under full load to be able to tuck the flywheel in closer to the rower. The C2 chain goes directly to the flywheel. We tested this type of idler cog system many years ago in an attempt to shorten the machine and discovered that there was a significant energy loss which is not measured by the monitor. C2JonW

The followups to that are quite relevant.

Both the new Rowperfect and the Oartec Slider both have the flywheel placed lower and run with this idler system as the first pulley. It doesn't seem to affect the pull, both feel quite smooth and effective, but these machines differ vastly in their monitors and scores. I tried the Slider for some time the other day and the scores seem spot on with the C2 to me.

It would seem to me that C2 are contradicting themselves by saying this about the Rowperfect and Slider, when the design on the new dynamic erg clearly uses more complicated idler cog system using a number of pulleys and links to drive the flywheel at the back of the machine. What does this mean for the scores on the dynamic, are they slower? How does the PM4 account for this significant energy loss?

Sorry I didn't mean it that way. What I was trying to point out is that the idea of hooking a C2 monitor up to some other system (different flywheel, magnets, drive means, etc) and expecting an equivalent score is a bit unrealistic. As for the comparability of scores between the C2 Dynamic and a C2 stationary erg, we're doing tests and gathering field information.

So far there are no results from that field information. I keep watch on the rankings but so far not enough people are using the dynamic, or slides, to make a relevant comparison. Personally I did like the slides quite a bit and would use them again. I am not impressed with the C2 dynamic.

[johnlvs2run]

Yeah My experience is only with the Oartec slider as far as dynamics go. I would love to try both the C2 dynamic and the RP indoor sculler but I don't know of any that are nearby.

Same for me. I am interested in your comments on the Slider in the meantime.

In response to JonW's comments, here is a comparison of the drive system on various ergs.

DIRECT DRIVE
C2 static ergometers
1xSculler's DIY dynamic erg (made with a C2 machine and parts)

SINGLE PULLEY PRIOR TO SPROCKETS
Rowperfect
Oartec Slider

MULTIPLE PULLEYS BEFORE SPROCKETS
C2 Dynamic

It is strange why Rowperfect, Oartec, and now C2 are putting additional pulleys prior to the sprockets.
C2 is the only one using a cord or a belt, so I give them major kudos for this, though still connected to a chain.

[kwadams]

Personally I did like the slides quite a bit and would use them again. I am not impressed with the C2 dynamic.

Hi John,

Curious why you are not impressed with the dynamic? Have you actually tried it or just based on what you see?

Thanks.
Kevin

[johnlvs2run]

Kevin,

I'm not impressed with the dynamic based on the videos that I've seen, especially the last few by C2 and their explanations. In the 36 spm video the guy pushed his legs out first which looked very easy, locked them at extension, then twisted his core and pulled with his arms. C2 printed on the video that it was excellent form for using the dynamic, but that form is the opposite of that used by the light lightweight rowers, Stephansen, Luini and Ebbesen. I never want to get a machine where I'd have to use form like on that video. So I don't know if that form is inherent from the C2 dynamic or just how the guy rowed but I want no part of it. I did enjoy using the model DCB on the slides, but on there I could use primarily legs with all the rest of the body, or even legs only if I wanted. So I'd consider the slides to be the standard to measure against. Also there is a direct drive on the slides.

I'm considering to get another rowing machine but am not sure yet between the various options available, am open to any of them and am looking to find out more about them.