Dynamic C2 vs. the "D", musing of Recent Dynamic Purchaser

[Ron Ginsberg]

Concept 2 Dynamic Musing, pro- con- who is it for?

I received my new Dynamic in January 2023 to be used with my existing 2004 model D. I thought my experience with it might be helpful to those contemplating making the switch, or for a first time purchaser, and might stimulate discussion of the pros and cons here on the forum.

First the context, I’m now 73 and I started rowing in the mid 80’s on a dual piston Tunturi. In 1990 I purchased a model B that I used until 2004 when I purchased my model D (sold the B, wish I’d kept it). In 1993 I had lower back disc surgery, in 2009 I had a heart attack, and in 2010 I had a hip replacement. From the time I started keeping a log on my model B, I’ve rowed more than 20 million meters. Currently I’m 5’6’’ 156 lbs.

When the slides were first introduced I had an opportunity to try them once and enjoyed them. When the Dynamic was introduced I was intrigued. This year I was determined to buy a second rower so that I could row where I spend my summers and not have to lug my rower around with me. My only decision was another D or a Dynamic.

I called Concept 2 to see if I could visit the factory and try a Dynamic in their workout room. Unfortunately they were renovating and the factory was closed to outsiders. They carefully went over their pros and cons and my situation, and were quite helpful, but they certainly did not point me to the Dynamic. Instead they seemed to lean more to the standard model D. However, they suggested that I try a Dynamic locally. It seemed that the Union College Rowing team had a number of them. The Coach could not have been more helpful, he invited me to their wonderful facility where I was able to sample not only the Dynamic, but also the bike erg. As an aside, he invited me to try their rowing tank so I was able to scull "on the water" for the very first time! That was a thrill. I loved the Dynamic. The next day I ordered one and it was delivered a few days later.

It was no more difficult to assemble than my model B. While it is not hard to assemble, it is not as easy to put together as a D. However, I had no trouble doing by myself within a couple of hours.

So… what’s the point of this. The point is I’ve never been a competitive on the water rower, I’m 73 years old, and I have had back injuries and a heart attack. Yet I find the Dynamic a delightful machine and a joy to work out on. I truly think that if more people had an opportunity to row on one, it is the machine they would buy for their own personal use.

The machine is more challenging. I find it forces you to have good form, and this is more challenging and even fatiguing because it urges you to expend more effort. On the D you can be sloppy and row any way you like. You can move too far forward on the catch and lean into the machine to far. On the Dynamic, your footpads seem to align near the seat where your shins are vertical and your torso is at 1 o’clock. Your arms are easily positioned horizontally and it takes effort to hold them up because the shock cord is not pulling the handle towards the flywheel.

You really notice the difference when you begin your drive. You push with your legs, and your body angle and arms don’t move. There is just this effort as the foot stretcher travels down the rail. Eventually your torso rotates back to about 11 o’clock and your arms finally move into your chest. Your butt stays on the forward edge of the seat and you are not aware of the seat moving at all.

The return is different as well. The D is tolerant of any sort of return, and the tension of the shock cord can really pull you along, especially if you are tired. Not so on the Dynamic. Here, you need to be conscious of the effort needed to pull your feet towards you. At the same time you bring your torso back to vertical and begin to raise your arms to the horizontal. There doesn’t seem to be any tension on the handle. There is no power assist from the shock cord. It is as if you have to serve the handle back to the front of the machine with no help at all and this takes effort. Of course there is some tension, but it is almost not discernible. The return on the Dynamic is notable because of the difference it has on the core. I find that the fact that I must control my torso between 1 and 11 o’clock on the forward portion of the seat works all the small muscles in my lower back and sides. The return also works all the muscles of the lower abdomen and pelvis. This is because your butt is immovable and you are using all these core and pelvis muscles to pull the foot stretcher back to your butt. It is more exhausting in a good way and much more demanding. It tends to tire me out more.

I’ve also determined that the reason I find it more tiring is because I tend to want to row at higher spm’s and paces. The Dynamic urges you to go faster and harder and I think this is because it encourages better and more consistent form. It also encourages quicker drives with slower recoveries. So I think I'm getting a better balance although my SPM is often higher, but even for the same SPM the balance is different, with a shorter drive and a longer recovery.

After a few weeks of rowing on the Dynamic, when I’ve returned to the D I’ve also enjoyed working out on it. It is like putting on an old soft shoe. I can relax and do anything I like.

I think the Dynamic provides a better all round work out. For someone like me, who wants to maintain strength in my core, and maintain strength in my legs for better balance, I think the Dynamic is ideal.

I would say that for cross training and occasional workouts for someone who is not an enthusiastic rower, the model D is more suitable. And it is certainly easier to row a D, anyone can do it and not necessarily feel very awkward.

I can’t disagree with Concept 2 with their marketing of the Dynamic to more competitive on the water rowers. I can easily see why the Dynamic would be a niche target market for those on the water, and typical gyms and home users would be steered to the D. However, I think that the are large numbers of enthusiastic home rowers of all ages who would prefer the Dynamic.

In terms of esthetics, it leaves much be desired. Additionally, it is heavier and not as portable. However, it does have a smaller footprint in use.

Since I’ve only has the machine a few months, I can’t say too much about maintenance. I clean the rollers after each row (more often than I do on the D) because there are more of them and they are more critical because of the design of the moving foot stretcher. The machine is built like the proverbial brick outhouse, but it is certainly going to be a bit more fussy than a D. But I don’t think much more fussy in home use.

[JaapvanE]

First of all, thank you for sharing your experience!

However, I think that the are large numbers of enthusiastic home rowers of all ages who would prefer the Dynamic.

One of the things I wonder about is wether the forces play out differently on a dynamic, making it more suitable for injury prone people. I can inmagine the drive is smoother on the arms and back. Is that your experience, or would you say it is more or less similar to your trusted D?

[Cyclist2]

Thanks for the detailed description of rowing the Dynamic.

I bought a pair of C2 Slides for my model C several years ago, to get more of the OTW feel, since I row OTW. Plus, I wanted a little less stress on my back at the catch. It works great and I'm happy with the setup. Fortunately, I have the room it takes so I can leave it assembled - it wouldn't be as nice if one had to set it up every row. Ugh.

I would be interested in how the Dynamic compares to an erg on Slides. Anyone have any experience with those two?

[Ombrax]

Ron, thanks for taking the time to write that - it's a interesting comparison.

Regarding the request for comparison to slides, somewhere on the forum I asked that very question and there is a reply.

Another option is to look for threads with "Slides" in the subject. There won't necessarily be a comparison to a Dynamic, but there is lots of information out there.

Here's one example: viewtopic.php?f=10&t=193293

[mict450]

Very good summary of the differences between static vs dynamic ergs. It's easier to "game" the static by using momentum & body weight to lower your splits. Such is not possible on a dynamic.

Overall my back & knees feel better after a session on a dynamic. Particularly after a hard session on a static, it takes me a while before I can stand up straight.

Only negatives on a dynamic I can see are increased cost & more moving parts, which means more maintenance & less reliability. The C2 A,B,C,D & rowErgs are practically bullet-proof by comparison. Can't go wrong with old reliable.

[Ron Ginsberg]

First of all, thank you for sharing your experience!

However, I think that the are large numbers of enthusiastic home rowers of all ages who would prefer the Dynamic.

One of the things I wonder about is wether the forces play out differently on a dynamic, making it more suitable for injury prone people. I can inmagine the drive is smoother on the arms and back. Is that your experience, or would you say it is more or less similar to your trusted D?

I didn't mention this in my first post, but I think I can posit a tentative answer based on my experience, although it is limited. I decided to improve my 2,000K time. It is a distance that I rarely row, so I tried a piece a few weeks ago while I was on Cape Cod for a few days using my model D. I went all out and realized that by the end of the piece my form was lousy. However, I did achieve a PB. Unfortunately, I strained my back. In ALL the years (over 30) I've been rowing on my models B or D I'd never ever strained my back, so I was shocked that this happened. In thinking about it afterward I realized that I had approached the piece with the mental attitude that I was still on my Dynamic. I thought I had the freedom to pull as hard as I could, so I did so not being aware that my form was going into the toilet. On the Dynamic I can pull at maximum effort, and somehow the mechanics of the machine naturally ensure that my form is better. It is harder to do, and perhaps more fatiguing, but it is also somehow more natural and built in. As an aside, I kept rowing and I added a few more stretches and back exercises to my usual routines, and in no time my back was was restored to normal. So I tried for a PB again, but this time on the Dynamic, and I achieved it without injury. So this is just a limited experience; however, I really do think that the design mechanics of the Dynamic put less strain on the lower back and provide some protection for someone who is a tad over enthusiastic and has bad form.

[cleister]

I would be interested in how the Dynamic compares to an erg on Slides. Anyone have any experience with those two?

out of the concept2 range I definitely prefer the dynamic. It's just a bit closer to OTW than what slides will give you. Not massively though, a RP3 for instance does much more in this respect, but I'd always choose the C2dyn over C2slides.

[Nomath]

There have been many scientific studies comparing the stationary C2 and the C2-on-slides regarding kinematic and physiological differences, but I know only one study involving the Dynamic. This study, titled Influence of Ergometer Design on Physiological Responses during Rowing, is available free of charge as a submitted paper ; the paper published in the Int. J. of Sports Medicine in 2015 is only available at a hefty price.
https://hal.science/hal-02078525v1/prev ... 02-023.pdf

The participants in this study were 11 young, competitive rowers, both men and women. A surprising result is that the gross efficiency on the Dynamic erg is found to be significantly lower than on the stationary erg. You would rather expect the opposite, as there is much less body movement on the Dynamic. The energy of moving the body back and forth on the monorail is usually offered as an explanation why the efficiency on a rowing ergometer is significantly lower than on a cycling ergometer.

The question whether the energy for body movement on a stationary erg is lost or is to some extent recovered in the drive, is a perennial debate on this forum. The comparison between a stationary C2 erg and the two dynamic ergs offers an intriguing new argument in this debate.

[Tsnor]

...This study, titled Influence of Ergometer Design on Physiological Responses during Rowing, is available free of charge as a submitted paper ; the paper published in the Int. J. of Sports Medicine in 2015 is only available at a hefty price.
https://hal.science/hal-02078525v1/prev ... 02-023.pdf

Really neat study. TY Nomath for posting it. 5 minutes to read, easy reading.

On a dynamic, rowing at the same split and output wattage, you'll have more waste heat generated, but also hit lower lactate levels while you row with less force per stroke at a higher stroke rate. Study cited other studies that confirm lower injury risk with dynamic vs static rower.

Study says the authors and just about everyone else makes assumptions based on "less displacement of mass = more efficient" yet their studies show the opposite. This study focused on dynamic, but listed other studies that tested slides. This study used experienced rowers, but referenced other studies that used inexperienced rowers. All studies end up saying the stationary rower is more efficient.

Study cites 2nd part of the drive (assume this is body over) as possible source for recovering the energy used to move body mass. "One possible explanation for the consistent higher ergometer rowing efficiency on SRE 260 may be that the kinetic work required to accelerate the body centre of mass at each stroke is 261 partly transferred/transformed as external (propulsive) work in the second part of the drive phase. " No mention of "elastic bounce at end of recovery/start of drive" or "shock cord".

Study also says lactate levels at the same power were lower with dynamic, and speculates this is from lower power per stroke X higher stroke rate on the dynamic. " At the present time, one can only speculate on the fact that the lower peak force for a given power output during rowing on DRE than on SRE may preferentially involve oxidative fibres and metabolism that may induce a lower lactate production and a higher removal/recycling" Clearly something different happens when you row the same splits on a dynamic vs a static rower.

Study lists gross and net efficiency measured is less than 20%, so 200 watt steady state rowing generates 800+ watts of body heat. Thus the need for fans for long pieces at room temp. (C2 used 25% for their efficiency in their calorie consumed reporting plus 200 FUD factor). Study also says multiple studies show rowing efficiency improves with load -- lower splits = more efficient for same rower.

[Hugh Trenchard]

Thank you for posting this interesting study. I've recently purchased a Dynamic C2, and am adjusting to the differences between the Dynamic and the static. I am noticing that my HR is significantly higher on a Dynamic at the same pace on a static, and almost certainly I won't be as fast on the Dynamic (haven't done any serious time trials yet) as the static. It is interesting that I am faster on the slides than on static, so I'm surprised to discover my Dynamics times will be even farther off my times on the slides.

I'm hoping that as I develop my technique, my Dynamics times will converge on my static times, but based on the study you posted and my experience so far, they will never quite match and I'll always be slower on the Dynamic. In terms of technique, I find that since the ratio of push vs. recovery time bobbles around 0.50 on the slides at a comfortable pace (and much higher of course at faster paces), this is a big adjustment over the static, where it's something like 0.38-ish for me at an equivalent comfortable pace, reflecting the much slower time taken to return up the slide. This difference takes a lot of adjustment in terms of setting up for the catch. Also, on the Dynamic your forward momentum allows natural leg compression and perhaps prepares the quads better for the push phase, compared with the Dynamic where your hamstrings do more work in setting up the catch and doesn't prepare the quads as much for the push phase because they are not pre-loaded by the natural leg compression.

I've checked out some videos about the Dynamics and from what I've seen, there isn't a lot of discussion about the differences in these push/recovery ratios and how that affects power transfer.

I also find the Dynamics to be noisier than the static, although it's a little deceiving because the fan is directly under you on the Dynamic - so hard to know, but footplate also makes a fair amount of noise.

I suspect I will eventually return primarily to using the static rower. My plan has been to try for a few age-group/lwt records on the Dynamics, but if/when I achieve those, likely I'll just return to the static for most of my erg time.

[Citroen]

I've cleaned the thread of lots of noise. Can we attempt to keep it on topic.

[Slidewinder]

So, I am not allowed to explain, without judgement, the mechanical design differences between the C2 Dynamic and other dynamics (even if the other dynamics are unnamed in the post)?
I am not allowed to comment that the researchers in study linked by Nomath seem unaware of mechanical design differences between the C2 Dynamic and other (still unnamed) dynamics?
I am not allowed to report, without judgement, the status of C2's patent applications for the dynamic unit?
That is a thick censorship filter.

[Citroen]

Correct. NOT ON THIS THREAD. It's off topic.

[Slidewinder]

Posting a link to a study of the C2 Dynamic (Nomath) is on topic, but commenting on that study (me) is off topic.
That's fair, and it makes perfect sense.

[jamesg]

Rowing on dynamic ergometer was associated with higher heart rate, oxygen uptake, carbon dioxyde production and stroke rate, concomitantly to lower blood lactate accumulation but also lower gross and net efficiencies.

Why lower Lactate? Lower efficiency for same power output should lead to more work done so more Lactate, not less. Or is the higher rating allowing better ventilation so L removal at a higher rate?

Surely these scientists should know how to spell Oxide.