Model D, Dynamic, Shox Box

[cas_sj]

Greetings Concept2 owners/rowers. I'm getting ready to make my purchase and have been researching models. I'm moving up from a Kettler Favorit piston style rower, so I know I'm going to step it up regardless of what unit I purchase.

Putting price entirely aside, I am considering a Dynamic rather than a Model D, primarily for the potential for avoiding back issues/aggravation. Replicating the feel of being on the water is not really a consideration - I indoor row for exercise, and may never actually get on the water.

Some questions: (1) Does performance on a Dynamic match up with the Model D? In other words, both of course come with the computer to match stats with others in the community, but is it "apples to oranges" or are the two models comparable assuming proper technique? (2) For those who have experience with it, would the rear Shox Box with a Model D be as effective as a Dynamic as far as avoiding back issues/aggravation? Is the front Shox Box a necessary part of the set up if you want to minimize aggravation of back issues from long sets?

Any other thoughts/experiences with these products much appreciated!

[PaulG]

The dynamic erg is supposed to be very comparable to the static (Model D)erg. A recent C2 newsletter had an article on comparative times and you may be able to find this on the website. I had a Model D and switched to a dynamic and my experience bears this out. I did two time trials at 1k distance as a 55 YO LWT. The first was a 3:27.3 on my dynamic and the second nine days later was a 3:27.1 at a competition on a Model D. It doesn't get much closer.

However, the comparability doesn't make a lot of sense to me. On the Model D at the catch you have to overcome the intertia of both the flywheel and your body mass as you reverse direction. On the dynamic you are only acclerating (and overcoming the inertia of) the flywheel. The feel is slightly different also. I feel that you have to keep constant hard pressure on the handles on the dynamic while with the Model D, if you are explosive enough at the catch with your legs, you can sort of coast through the rest of the stroke. Perhaps the momentum of your body after the catch allows you to continue the stroke with less effort.

I feel that the dynamic is easier on the back because you are only accelerating the flywheel. Then why are the times comparable? I have had less back pain with the dynamic than the Model D. However, because of the need to keep constant hard pressure on the handle, I have developed tendonitis in my elbow which I never had before. (diagnosed as golfer's elbow....oh the shame)

The other major difference is on the recovery. I haven't heard anyone comment on this before, but you get a free ride on the Model D as move up the slide to the catch position. The slide is sloped slightly donwhill and the tension of the chain will also help you on the recovery. On the dynamic you have to actively pull the footplate up to your body with your hamstrings and hip flexors. There has to be some energetic cost to this.

In summary C2 and my empirical experience says that performance should be very close. My limited understanding of Newtonian physics does not explain why. Maybe someone who knows more about classical physics can explain it.

I have no experience with the ShoxBox.

Paul

[Dreadnought]

However, because of the need to keep constant hard pressure on the handle, I have developed tendonitis in my elbow which I never had before.

I would have thought that the constant pressure would be less likely to cause tendonitis, compared to the impact of a sudden explosive pressure.

I actually developed the same problem with the Model C, and I had to stop erging for several weeks.

I now use lifting hooks to grasp the handle, as they prevent me from gripping it too tightly, so I no longer have the issue with twndonitis

http://www.schiek.com/1200hooks.html

At first it felt strange, wasn't sure if they were going to slip off the handle, but after a feww minutes of erging, it was all good.

[vandons]

However, because of the need to keep constant hard pressure on the handle, I have developed tendonitis in my elbow which I never had before.

I would have thought that the constant pressure would be less likely to cause tendonitis, compared to the impact of a sudden explosive pressure.

I actually developed the same problem with the Model C, and I had to stop erging for several weeks.

I now use lifting hooks to grasp the handle, as they prevent me from gripping it too tightly, so I no longer have the issue with twndonitis

http://www.schiek.com/1200hooks.html

At first it felt strange, wasn't sure if they were going to slip off the handle, but after a feww minutes of erging, it was all good.

I have been having some problems with tendonitis which I've been getting when I erg a lot. Very frustrating. I am going to try out the lifting hooks. Great idea.

[Rob]

The dynamic erg is supposed to be very comparable to the static (Model D)erg. A recent C2 newsletter had an article on comparative times and you may be able to find this on the website. I had a Model D and switched to a dynamic and my experience bears this out. I did two time trials at 1k distance as a 55 YO LWT. The first was a 3:27.3 on my dynamic and the second nine days later was a 3:27.1 at a competition on a Model D. It doesn't get much closer.

However, the comparability doesn't make a lot of sense to me. On the Model D at the catch you have to overcome the intertia of both the flywheel and your body mass as you reverse direction. On the dynamic you are only acclerating (and overcoming the inertia of) the flywheel. The feel is slightly different also. I feel that you have to keep constant hard pressure on the handles on the dynamic while with the Model D, if you are explosive enough at the catch with your legs, you can sort of coast through the rest of the stroke. Perhaps the momentum of your body after the catch allows you to continue the stroke with less effort.

I feel that the dynamic is easier on the back because you are only accelerating the flywheel. Then why are the times comparable? I have had less back pain with the dynamic than the Model D. However, because of the need to keep constant hard pressure on the handle, I have developed tendonitis in my elbow which I never had before. (diagnosed as golfer's elbow....oh the shame)

The other major difference is on the recovery. I haven't heard anyone comment on this before, but you get a free ride on the Model D as move up the slide to the catch position. The slide is sloped slightly donwhill and the tension of the chain will also help you on the recovery. On the dynamic you have to actively pull the footplate up to your body with your hamstrings and hip flexors. There has to be some energetic cost to this.

In summary C2 and my empirical experience says that performance should be very close. My limited understanding of Newtonian physics does not explain why. Maybe someone who knows more about classical physics can explain it.

I have no experience with the ShoxBox.

Paul

Well I haven't though much about it this way before and I'm certainly no physics expect, but this is an interesting question. I can see how the load on a static erg would start heavy at the catch and ease off (comparatively) throughout the stroke while the force during the dynamic's stroke is more even: I suspect the back pain (which is why I purchased slides for my model D) is caused by the higher peak load/force on the static erg.
I think though, if we think about where the actual work is going there is less difference than we think between the two ergs. First off, on the dynamic (and more so with the erg on slides) there is still weight to be moved back and forth: of course for a typical male, that would still leave 150 lbs more or so to move back and forth on the static. On the static (and you can probably see this when rowing without straps on the feet) the initial work to accelerate the body get dissipated back into the flywheel as the body comes back to a stop at the finish. Of course there are inefficiencies such as air resistance (probably negligible: and present when moving the dynamic/slides too) and just the losses in the body from producing the forces to change the body's direction, but I suspect they may be less than we might think. On the dynamic, you probably lose a little efficiency too when producing force a little more evenly throughout the stroke and some is being moved from the early leg drive to the arms and body swing.

[Slidewinder]

So, here we have three posters all stating that they have developed tendonitis as a result of using the C2 rowing ergometer. This, I am certain, is not related to whether the device is static or dynamic, but as a result of pulling on that rigid, single-piece, bio-mechanical abomination of a handle.

Individuals have e-mailed me confessing that their condition is so severe that they can no longer row! Users of rowing ergometers should be publicly raging about this, not sending timid, private e-mails to me.

[Rockin Roland]

So, here we have three posters all stating that they have developed tendonitis as a result of using the C2 rowing ergometer. This, I am certain, is not related to whether the device is static or dynamic, but as a result of pulling on that rigid, single-piece, bio-mechanical abomination of a handle.

Individuals have e-mailed me confessing that their condition is so severe that they can no longer row! Users of rowing ergometers should be publicly raging about this, not sending timid, private e-mails to me.

Nice try, but the handle has nothing to do with it. If C2 users develope muscular & joint problems in the arms, regardless of whether it's a dynamic or static erg, then the erg is not the problem. IT'S POOR TECHNIQUE which is the cause of the problem. I see this often enough in boats too.

There are so many people out there using incorrect technique, too much upper body, over emphasis with the arms and incorrect body sequence. Wouldn't matter what type of erg their on or which boat they are in. They would row badly on anything. It would be more benefical to get some good coaching then mistakenly believe that two handles or a different movement is going to completely transform their rowing.

No use having the best equipment if you don't have the skills or knowledge to row properly.

[c2jonw]

A number of issues here, most of which have been addressed but I'll add a couple comments.
As mentioned, scores on the Dynamic are comparable to scores on the stationary machines. However, similar to stationary ergs VS ergs on slides, some people may score better on one or the other, and optimal technique for each type will be different.
Besides the amount of moving mass and the angle of the monorail, one other difference between a stationary erg and a dynamic is the mechanical efficiency. The stationary C2 machines are a direct drive- the chain goes over the sprocket which spins the flywheel. In the C2 dynamic there are some additional pulleys to transfer the energy from the handle and moving footstretcher to the chain and on to the flywheel. Each loaded pulley adds inefficiency. The foot stretcher assembly moves on rollers which also have an energy cost but may be offset by the relatively stationary seat on the Dynamic.
Elbow tendonitis can have a lot of causes but I would look at technique and particularly at how the handle is being held. A full handed "death grip" is not needed- your grip should be light with only the end two joints of the fingers being bent. RELAX your hands during the recovery- switch the thumbs from the top to the bottom of the handle and lighten up the load setting.
We have very limited experience with the Shox Box.

Hope this helps, C2JonW

[Slidewinder]

If the handle was a bio-mechanically correct design it would not be necessary to grip it loosely as suggested. If the handle followed the user's natural movement as the stroke progressed and thereby maintained alignment of the user's hands, wrists, and forearms with the direction of applied force, a firm grip (not a "death grip") would pose no risk of injury to the user.

The rigid, single-piece handle is a poor design. It forces the user to adapt to it, rather than the other way around. It is causing repetitive stress injury to users. In some cases that injury is permanent. Blaming the user exonerates Concept 2 from responsibility and allows Concept 2 to refuse to acknowledge that the handle design is the root cause of these reports of user injury.

[Ergmeister]

Here we go again.

[Slidewinder]

Thankyou Ergmeister for your thought provoking contribution to the discussion.

If Concept 2 knows that a loose grip on the handle reduces the risk of injury, then every unit should bear a warning label to that effect. It is irresponsible not to inform the public of this. Of course, a properly designed handle would not require advice and warnings about how to hold it.

In the Mary Poppins world inhabited by many posters on this forum, it is just not possible that Concept 2 would equip their rowing ergometer with a handle that causes injuries to users. To even suggest that possibility is heresy. So rather than demand that Concept 2 do something about the stone age stick of a handle, the response is to blame and ridicule the injured themselves. "Poor technique!" Jeer the C2 groupies. "That is the cause of their injuries." But contrary to the bellowed put downs of RockinRoland and his fellow jeerleaders, there is no "proper technique" that can overcome the inherent defects of the C2 stock handle. Here's why:

At the beginning of the stroke, if one were to draw an imaginary straight line along each of the user's extended arms and terminate those two lines at the pull chain, the lines would form a long equilateral triangle, with the base of the triangle being the distance between the shoulders. As the stroke progresses, and the handle is pulled towards the body, the triangle shortens. The base of the triangle, being the distance between the shoulders, remains unchanged. So, as the stroke progresses, all of the angles of the triangle are in flux.

In the middle of this changing geometry is the rigid, single-piece handle. Its length, and the angle of its grips remain fixed, while the angles of the user's limbs change in relation to it. Therefore it is impossible for the user to keep the hands, wrists, and forearms aligned with the direction of applied force. You want to injure yourself? Using the C2 stock handle is a good way to do it.

To add insult to injury (an apt expression here), the C2 handle forces a movement that replicates no known rowing stroke, neither sculling nor sweep.

Concept 2 cannot plead ignorance of these facts. It is basic, high school geometry.

Users of the C2 rowing ergometer are being injured, some of them for life. Convince me that the C2 rigid stick of a handle is not the cause.

[Slidewinder]

Earlier in this thread "Dreadnought" states he (I'm assuming "he") uses lifting straps in place of the C2 stock handle to avoid aggravating the injuries he apparently sustained while using the C2 rowing ergometer. It's a telling comment that this improvised rig improves upon the C2 supplied handle. The lifting straps provide relief because they do what the C2 handle should do, but doesn't - ensure that the hands, wrists, and forearms remains aligned with the direction of the applied force throughout the stroke.

Another important design consideration is the natural angular relationship of one's grip to the wrist and forearm. Grip a short piece of dowel in your hand and hold your arm extended. In the most comfortable and natural position, the dowel will not be at right angles to the wrist and forearm, but at a slight angle. This is the reason the grip of a pistol is not perpendicular to the barrel.

Concept 2 got it partially right by incorporating a slight angle in the grip of the current mono-bodied handle, but since the angle of the user's limbs change in relation to the handle as the stroke progresses, an ergonomically correct angle of hand to wrist is not maintained throughout the stroke, and since this occurs while the wrist is under load and stressed, the risk of injury is very real.

Take off the rose coloured glasses. Users have endured this for more than thirty years.

[jamesg]

the angle of the user's limbs change in relation to the handle as the stroke progresses

Not necessarily. My handle has the same width as my shoulders, so in plan view, the wrist-hand-handle angles need not change. They will if I spread my elbows, but I don't. I also keep my wrists flat. These are both C2 rules if I remember right. Some ergers break both rules, and some horrendous postures can certainly be seen on the erg, but easily avoidable and not forced by the erg.

To me it seems that C2 chose that handle width precisely because it IS equal to my shoulder width. Or just my luck?

You do well to warn of risk, but I think there's more than one way of avoiding it, and in any case it's a balance. I have to do something to keep fit.

Risk can be expressed in numbers so that we can see how important it might be. If ergers and oarsmen are 0.1% of the population and they run a 0.1% risk of repeated stress injury, that's 1 per million of the population, open to a hazard that might be reversible anyway. Not like falling off a bike and under a bus; and not like getting heart disease due to smoking drinking obesity and lack of exercise that seem to involve (or should I say, kill) around half the population.

This site has a pdf that describes common rowing injuries: http://www.stopsportsinjuries.org/rowin ... ntion.aspx
The page (at the end of the pdf) dedicated to the erg indicates high drag as the main cause of complaint, unsurprisingly.

[Slidewinder]

Thankyou for the unemotional, reasoned reply.

No doubt keeping the hands flat and elbows in are viable injury preventative measures when using the C2 stock handle. Nevertheless, these measures are accommodating human movement to the restrictions of the handle rather than the other way around, as would occur with proper intelligent design.

The erg users earlier in this thread who discussed the use of lifting straps for pain relief, are probably not as forgiving of the C2 handle design as you. Maybe their shoulder widths differ from the width of the handle. Maybe they don't keep their hands flat. In any case, it is a mean spirited conclusion that that they are to blame for their injuries and not the handle. A handle design that ensures hands, wrists, and forearms remain aligned with the direction of applied force regardless of user physiology or wrist orientation is clearly superior to the C2 design which doesn't. The testimony of users turning to lifting straps for relief supports this truth.

(I was surprised to read in the row injury link you supplied that rib stress fractures account for 10% of all rowing injuries)

[cas_sj]

Greetings c2forum posters.... Wow, this is a really fun example of a post getting totally hijacked - my post actually, from a year ago. If the original subject matter/question was of no interest to the community, you should have let the thing die a natural death.

Forgive me Slidewinder, and I'm a big fan of entrepreneurialism and invention and better design, but your input really doesn't have a thing to do with my original inquiry. Perhaps other responses prompted you to take over the thread, but there's nothing in your posts here that addresses my original question. You've got a lot of input/posts elsewhere on your invention already, no need to take over this thread.... Good luck with your invention.

For anyone interested in the original subject, after a year and a million plus meters on the thing, I give a big two thumbs up to the static with the rear shox box.

Cheers and Happy New Year.