Concept2 Forum

Is it normal to have 4-6" of "slack" in the chain at the beginning of the drive phase. Seems that the flywheel isn't "engaged" for the first few inches. Drag setting on 4.5 (122) , 200 watt drive, drive length 1.27m
Is it my technique? or normal? feel I'm losing some power somewhere

By chain slack do you mean due to the bungee cord not pulling enough chain, or do you mean you pull on the handle and the sprocket spins freely without causing the flywheel to turn? Sounds like the latter, in which case how old is your erg, and have you ever cleaned/flushed and re-lubed the clutch mechanism? (I don't believe that's a regular part of the maintenance schedule, but given the symptoms it seems relevant.)

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The slack is the distance it takes us to accelerate our entire body mass (and the handle) to flywheel speed. The flywheel is stationary only at the first stroke, after that we have to catch up with it before the chain can engage.

Thanks, I am assuming it is the "catch up", C2 is new and so don't think it is the clutch. Feels weird though, have tried to drive "harder" but still get the "slack"

Two things:

1) What's your stroke rate? Unless you're racing or sprinting super-hard you should probably be around 20-24 strokes / minute, which should give the flywheel a bit more time to spin down, in which case it won't be quite as hard to catch up to it.

2) Try a more "explosive" start to the drive. Hard is important, but so is "controlled fast."

Consider posting a screen shot of the force curve for a typical drive, one in which you're feeling what you describe as slack. It should reveal whether the clutch is/isn't engaging at the start of your drive....

Seems that the flywheel isn't "engaged" for the first few inches.

Exactly. The chain engages when we engage it. The erg is not static, like lifting a weight, it's moving, like a boat, so we have to catch up with it. Your numbers are perfect.

If the clutch is faulty or frozen, we fall off the end of the slide; zero resistance.

You shouldn't have any "slack" in the chain with zero resistance as the clutch engages the instant you start the drive. In my experience, when clutch bearings fail they are usually fouled with lint and dust and they will make a clicking noise and you can feel the loss of contact continuously in the drive with jumping resistance from normal to nothing (like a slipping clutch), but not a complete failure to where you fly off the back. You should have about 8 lbs of pressure required to move the flywheel from a dead start which you can check with a fish scale on the handle while resting in the slot. You can clean those clutch bearings out with an air hose and blow-down tool or spray oil with the flywheel off and lying flat. Spray air or oil in both ends of the clutch bearing and you'll see crud come out on a rag and that will usually restore function in a wonky clutch bearing. You should put a few drops of oil in when you're done. If you need to replace it, C2 wants the whole flywheel back to do that for you as they need to re-balance the flywheel and set the clutch bearing in there properly. It can be done (by you) but it is tricky and you need some specific tools.

Ergmeister wrote: ↑

February 21st, 2020, 8:14 am

You shouldn't have any "slack" in the chain with zero resistance as the clutch engages the instant you start the drive.

How do you define "start the drive"?

When you start pulling the handle?

Thanks all, "start the drive" is when I begin the push with my legs, not yet "pulling" with arms. Following the sequencing of legs/back/arms. As I drive with the legs my arms and hands sense no "resistance" via the chain or handle for about 6". This is what i am talking about. Force curve is a smooth bell curve (for the majority of drives). I would think the clutch would engage immediately upon the drive but maybe I am just not creating enough velocity in that first 6". My question is am I losing efficiency by not having that first 6" add to the drive (virtually shortening my drive length by 6")and how much is that effecting me overall.

Mcgyver wrote: ↑

February 21st, 2020, 6:26 pm

My question is am I losing efficiency by not having that first 6" add to the drive

I would think that that is definitely not what you want.

Unfortunately, I'm not enough of a "teacher / expert in understanding how users or the erg itself go wrong" to diagnose the fundamental problem.

I do know that if you don't push hard or fast enough you can't apply torque to the flywheel. I also know that as soon I as start the drive I can immediately feel the inertia and drag of the flywheel are resisting my attempt to bring the flywheel back up to speed. There is no noticeable "no resistance" part of drive.

One option would be for you to post of video of you rowing for a minute or so. A clear shot from the side should allow the folks here who truly are experts diagnose the problem.

Mcgyver wrote: ↑

February 21st, 2020, 6:26 pm

I would think the clutch would engage immediately upon the drive but maybe I am just not creating enough velocity in that first 6".

Perhaps I am stating what you already have understood, but just to be sure:

When you start the drive, the flywheel is still spinning. You need to catch up with the speed of the flywheel before the clutch can engage, no matter how perfect the clutch is.

It is a bit like riding a bicycle and pedaling it with a cadence of 40 RPM, while you would need 60 RPM to match the actual velocity of the bicycle at the chosen gearing. Your pedaling can't keep up with the speed of the bike, so the freewheel mechanism will not engage, and you will feel no resistance at all.

So on a rowing ergometer , there will always be some slack at the beginning, until you have accelerated the handle up to match the rotational velocity of the flywheel.

What you should do to minimize that slack, I will leave up to the experts. Personally, I do nothing else than applying so much force with my legs that I can catch up with the flywheel as fast as possible. And then I try to keep a strong posture so I don't lose it all in "body springiness" when I do catch up.

(I know someone who tried to counter the slack by twisting his arms at the beginning of the drive. But he stopped doing it after talking to some top rowers at a local championship who told him that he was actually using more energy that way.)

Mcgyver wrote: ↑

February 18th, 2020, 10:04 pm

Is it normal to have 4-6" of "slack" in the chain at the beginning of the drive phase.
Seems that the flywheel isn't "engaged" for the first few inches. Drag setting on 4.5 (122)

There was a previous discussion of that slack on this thread.
My Skierg has the same slack at the catch, due to having the same type of clutch as the Rowing machine.
The slack is not as noticeable at low ratings. Conversely, it is more noticeable at higher ratings and lower drag factors.

Another test: do you still feel the 4"-6" of slack from a standing start, when the flywheel is not spinning at all?

At the start one has to push/pull extra hard to get the flywheel up to speed as quickly as possible. It should be very, very obvious if there's an issue with the clutch, or not. If there isn't, then in all likelihood the "slack" that you think you're feeling is a problem with your "up and away" technique at the catch. (If you're willing to come up to speed slowly, then you could conceivably not pull hard, and not feel a lot of resistance, but you'll still have to exert some force on the chain to cause the flywheel to spin.)