C2 Erg Prototype

[Bob S.]

Warren,

What do you think is the case of the herky-jerky on the prototype?

John

John,

As far as I know, the only herky-jerky involved was the start of the power curve in NavHaz's photo. I was there when he did that piece and he was going at an intense, very high rate. It was no wonder that the power curve was a bit herky-jerky. If it had been a grounded erg, it would have been jumping around like a grass-hopper - as I have seen Nav do on an another occasion when I was right next to him and a bit apprehensive about it.

My own experience on the prototype was very positive. The action was smooth and it was very easy to row at higher rates than I normally use. I was cruising along at 38 spm and not even aware of it until I glanced at the rate meter.

Bob S.

[badocter]

On a current model erg either with or without slides, there is a significant inertial element that dampens out unevenness in the stroke to an extent. On a fixed model, your body is that inertial element, on slides it is the erg itself (60-70 pounds). On the water, it would be the shell. On this new model, there really is no inertial element, so there is no damping of stroke unevenness. I think mounting 30kg of iron to the stretcher assembly should provide the same level of damping as currently exists on ergs with slides.

On the other hand, working out the stroke uneveness might be a good thing to do (the key word being "might"), but it will probably present more barriers and frustration to newbies.

The current protoype compared to an erg on slides looks analogous to a Keiser air resistance machine compared to a Nautilus weight stack machine. On the Nautilus if you build momentum at the initial phase of a lift you can use inertia to coast throught the middle....on a Keiser you can't.

[johnlvs2run]

John,

As far as I know, the only herky-jerky involved was the start of the power curve in NavHaz's photo. I was there when he did that piece and he was going at an intense, very high rate. It was no wonder that the power curve was a bit herky-jerky. If it had been a grounded erg, it would have been jumping around like a grass-hopper - as I have seen Nav do on an another occasion when I was right next to him and a bit apprehensive about it.

My own experience on the prototype was very positive. The action was smooth and it was very easy to row at higher rates than I normally use. I was cruising along at 38 spm and not even aware of it until I glanced at the rate meter.

Bob S.

Bob,

I am referring to the herky-jerky movement of the seat in this video.

http://www.youtube.com/watch?v=FTN_9msFKTg

[johnlvs2run]

I think mounting 30kg of iron to the stretcher assembly should provide the same level of damping as currently exists on ergs with slides.

Perhaps that would also work in a boat.

[Bob S.]

Bob,

I am referring to the herky-jerky movement of the seat in this video.

http://www.youtube.com/watch?v=FTN_9msFKTg

John,

I was referring to the following, which was the first place where I saw the term used on the forum:

FWIW here's a force curve off the prototype:

Photo courtesy of Mary Van Buren.

The herky-jerk bit in the catch is from unfamiliarity with the prototype as opposed to a grounded erg, and from seeing what would happen if you were to try to 'gorilla' the stroke.... In my defense I was in street clothes....

Note that there is a considerable difference between the initial prototype demonstrated at the HOTC and shown in the video above and the later version (still a prototype) in MVB's picture taken 3-4 months later at the C-B's. The woman shown in the HOTC photo is going a very slow rate. The herky-jerky effect is exactly the same thing that I experienced with a regular erg when I first tried out slides and was trying to go at a low rate (12-15). But, as I said, the new prototype is definitely different from that first one that they brought to the HOTC. To know if the new one shows that effect, we would have to see a video. So far I have just seen stills.

The national team has one of the second round prototypes to try out and will no doubt be giving C2 a lot of useful feedback for any redesigns.

Bob S.

[badocter]

I am referring to the herky-jerky movement of the seat in this video.
http://www.youtube.com/watch?v=FTN_9msFKTg

The current protoype does not have that setup anymore. The seat now sits on the main rail and there are bungies inline with the rail to dampen the seat movement a bit. C2jonw told me at CRASH-B that these changes were in response to people constantly hitting the stops on the first prototype.

I think mounting 30kg of iron to the stretcher assembly should provide the same level of damping as currently exists on ergs with slides.

Perhaps that would also work in a boat.

On the water the 30kg attached to the stretchers is the boat. Now that I look it up I see a 1x can be as low as 14kg....so perhaps 30kg more accurately simulates a sinking boat.... The drag of the water also provides some additional damping as well.

[johnlvs2run]

The seat now sits on the main rail and there are bungies inline with the rail to dampen the seat movement a bit.

I was just going to post about this.
Notice in the current prototype photo that there are long bungees going to the seat.
No wonder it bounces back and forth.

C2jonw told me at CRASH-B that these changes were in response to people constantly hitting the stops on the first prototype.

Fixing the seat (or similar) would put a stop to that immediately.

perhaps 30kg more accurately simulates a sinking boat

Agreed. The prototype probably weighs more than that.

The drag of the water also provides some additional damping as well.

Right, and likewise the fan is plenty of resistance.
Now if only the power was based on weight, as is done otw.

[Bob S.]

On the water the 30kg attached to the stretchers is the boat. Now that I look it up I see a 1x can be as low as 14kg....so perhaps 30kg more accurately simulates a sinking boat.... The drag of the water also provides some additional damping as well.

I don't know where you came up with the 30kg. 30 pounds is about right for a run of the mill single. I think that some of them, especially those designed for lightweights, might be as low as 26#, but I vaguely remember something about a FISA minimum weight for safety considerations. I did hear something at the C-Bs about the stretcher assembly being 30#. I figured that, if this were correct, it might be intended to approximate the weight of a single. I don't know how it works out for the crewed boats, but it is probably not too far off from the boat weight divided by the number of rowers.

Bob S.

[bloomp]

For what it's worth, and I have no video to back it up, the new prototype is not 'herky-jerkey'. I rowed it at 10spm, no issues. I rowed it at 70spm, no issues. It takes more concentration than a grounded erg, sure. But it takes a hell of a lot less concentration than rowing a 1x.

Many of you are forgetting that there's a forest around all those trees. The big picture is that C2 is offering what you've been bitching about for years now. For the ergometer to be truly 'dynamic', the seat has to move. You again face the problems of the grounded erg when you start locking things in place. What is the complaint of Roland & Co.? That the grounded fixture:

a) favors heavyweights and unskilled rowers over those with the fine motor control and muscle memory that have actually mastered the skills of rowing, and;

b) places undue strain on the lower back, which is caused in part by having the back stop moving so suddenly when transitioning through the stroke. By unlocking the seat C2 essentially removes the lurching motion that happens when the back begins to unfold and the legs have finished snapping downward.

In response to part A, as seen with Nav's 'herkey-jerkey' force curve, there may be an inherent disadvantage to behing a heavyweight on the prototype. OTW, it's hard for a big man to haul himself up and down the slide of a single fast while maintaining proper technique. And staying afloat might prove to be difficult.

My final two cents: if sliding-rigger boats were allowed, this would be an excellent simulator for that motion.

[johnlvs2run]

For the ergometer to be truly 'dynamic', the seat has to move.

I disagree. What makes you think the seat has to move?

You again face the problems of the grounded erg when you start locking things in place.

Not at all, because a grounded erg is fixed - not balanced.

favors heavyweights and unskilled rowers over those with the fine motor control and muscle memory that have actually mastered the skills of rowing

This is primarily because power can be generated on the erg, without the accountability of one's weight.

places undue strain on the lower back, which is caused in part by having the back stop moving so suddenly when transitioning through the stroke. By unlocking the seat C2 essentially removes the lurching motion that happens when the back begins to unfold and the legs have finished snapping downward.

Not so. The prototype would be more balanced by being in tune, then by having a herky-jerky seat.

In response to part A, as seen with Nav's 'herkey-jerkey' force curve, there may be an inherent disadvantage to behing a heavyweight on the prototype.

The only "disadvantage" to heavyweights would be having power output based on weight, the same as otw.

[badocter]

...so perhaps 30kg more accurately simulates a sinking boat...

I don't know where you came up with the 30kg.

30kg is the mass of a Model E, thus if the erg is on slides the inertial mass attached to the stretchers is 30kg.

[bloomp]

For the ergometer to be truly 'dynamic', the seat has to move.

I disagree. What makes you think the seat has to move?

You again face the problems of the grounded erg when you start locking things in place.

Not at all, because a grounded erg is fixed - not balanced.

I hate to point out the obvious, but you haven't tried the prototype yet. There is no 'balance' involved with the prototype. Actually, I'm honestly not sure what you're trying to say by that.

favors heavyweights and unskilled rowers over those with the fine motor control and muscle memory that have actually mastered the skills of rowing

This is primarily because power can be generated on the erg, without the accountability of one's weight.

Yes, and but by approaching the reality of a boat (which I'm still not sure if you've ever been in), there is more and more of a penalty by NOT knowing how to row properly. Again, you haven't tried the prototype. When I hopped on to cool down after my race, I started with a less-than-proper technique and it sucked.

places undue strain on the lower back, which is caused in part by having the back stop moving so suddenly when transitioning through the stroke. By unlocking the seat C2 essentially removes the lurching motion that happens when the back begins to unfold and the legs have finished snapping downward.

Not so. The prototype would be more balanced by being in tune, then by having a movable seat.

And again you are throwing out vague and unrelated terms. "In tune" has to do with an instrument, not a rowing simulator. I assume you mean "in tune" with the people's demands. In that case, you are not the entire populace and I'm inclined to say your lack of knowledge of physics in general disqualifies you from arguing against this.

To maintain a steady acceleration of the handle it takes a lot of force from the entire body. The legs can readily provide that but improper use of the back in attempting to continue such a force can result in injury. If the seat provided some flexibility in it's movement (instead of coming to a complete stop when the legs are done), there would be much less of an issue. Hell, the seat isn't even completely stopped when using a grounded erg. It moves an inch or two between the final leg drive and the finish of the stroke.

In response to part A, as seen with Nav's 'herkey-jerkey' force curve, there may be an inherent disadvantage to behing a heavyweight on the prototype.

The only disadvantage to heavyweights would be having power outputt based on weight.

Yes, they are most disadvantaged by that.

John, try the prototype, then get back to me. You'll realize the fact that the seat moves is not bad at all. Again, the big picture is that C2 has made a huge step forward and responded to the needs of the community.

[Bob S.]

...so perhaps 30kg more accurately simulates a sinking boat...

I don't know where you came up with the 30kg.

30kg is the mass of a Model E, thus if the erg is on slides the inertial mass attached to the stretchers is 30kg.

But this quote of yours specifically says boat, not erg:

On the water the 30kg attached to the stretchers is the boat.

I had wondered how you came up with 30kg for a boat. It is not unreasonable actually, since some of the recreational singles weigh that much. I would have gotten one for use here except for that. It would have been too damn heavy for me to transport and launch.

Bob S.

[johnlvs2run]

I hate to point out the obvious, but you haven't tried the prototype yet. There is no 'balance' involved with the prototype. Actually, I'm honestly not sure what you're trying to say by that.

You might be interested to know that I did row on slides for awhile, and my results were 3 to 5 seconds faster per 500m than on the erg on the ground.
Based on your other post, this shows that my rhythm and feel for the erg movement are quite excellent.
That is not the case with many rowers on the forum, as many of them have admitted to not being able to go any faster on the slides.
This is plenty of proof that I have a quite excellent understanding of balance and also of power per weight.
You are right that I have not used the prototype, but IF it is more like the slides than a grounded erg, then it's balance is quite important.

by approaching the reality of a boat (which I'm still not sure if you've ever been in)

Let's not let facts get in the way of reality.

there is more and more of a penalty by NOT knowing how to row properly.

Exactly, but I'm tending to be convinced the prototype is not yet comparable to the slides.

When I hopped on to cool down after my race, I started with a less-than-proper technique and it sucked.

So......... does this mean you are agreeing with me?

And again you are throwing out vague and unrelated terms.

Perhaps you just do not understand them, a not uncommon occurance.

"In tune" has to do with... blah blah... (nothing to do with what I said) .... your lack of knowledge of physics... blah blah.

Actually I got straight A's in physics.

To maintain a steady acceleration of the handle it takes a lot of force from the entire body.

Perhaps you don't realize this, but the center of gravity of the body is only slightly above the hips,
i.e. slightly above the seat, and does NOT move back and forth to any great degree on the slides, nor should it on the prototype.

The CofG should move in the same direction as the upper body, the opposite direction of the legs - not in a herky-jerky fashion.
See the photos of Warren on the erg to see excellent illustration of this.
http://www.c2forum.com/viewtopic.php?p=127898#127898

I am not disagreeing that there could be some play in the seat, as well as that the seat could be fixed.
I am saying that the herky-jerky movement of the prototype is not balanced.

Yes, they are most disadvantaged by that.

Yes, they are so disadvantaged, that it is almost like rowing in a boat.

John, try the prototype, then get back to me.

Well, Paul, send one to me to do with what I want, and I will be glad to get back to you.

You'll realize the fact that the seat moves is not bad at all. Again, the big picture is that C2 has made a huge step forward and responded to the needs of the community.

I believe that I did not say the seat should not move, but that a fixed seat would cure the herky-jerky movement of the prototype.

C2 has not made a huge step forward, or rather a catch up step yet.
Only when the prototype is developed and tuned would that happen, which remains to be seen.
I remind you that Warren came up with his design more than 9 years ago, approached C2, and they had no interest at that time.

[bloomp]

John,

The reality of the situation is that balance is not required on land. Unless you add a CorePerform to your rowing machine, you just row and don't have to worry about setting a boat. Again, you refuse to tell me if you have actually rowed before.

Ignoring everything else, I just wanted to emphasize that I did not find the prototype to be herky-jerky. I rather appreciated it. I earnestly hope you get a chance to try one. It's not as bad as you think. The C2 representative I spoke to said the earliest it would be out is in six to nine months. Plenty of time to continue testing and 'tune' it to the feedback.

9 years ago the primary concern of C2 was establishing a base market for their machine. It is a business and now that rowing has boomed to being a huge sport at all ages, it's easier to supply a rowing-tailored machine - not just a machine that could be used for general fitness. Had C2 put its time and effort into a machine that was 'difficult' to row, they would have lost a huge amount of business from gyms that just need another cardio machine.