How to stop my machine migrating off the mat

[jackarabit]

Compiled consensus: forward is toward the fan cage (equivalent to aft in shell) caused by slamming into the catch; backward is toward leg at rear of monorail (equivalent to bow in shell) caused by vertical vector component at initiating drive. You’re welcome.

My take: strong leg extension combined with nearly spasmodic early backswing and elbow contraction causal. Maybe hands pulling great circle route to neck and high shoulders rather than level with lats. See that front lift in many sprint record attempts. Strong association with 3/4 stroke and high spm.

[jackarabit]

Dangerscourse writes:

Finally, you want more of a vertical stroke, otherwise you can come off the seat more easily as you're pulling up and out of the seat

Stu, I hope you meant horizontal? Yeah, I know you did. Here in DelMarVA (mid-Atlantic US) our local telephone company is called ‘VERIZON.’ ClevernessCorruptionConfusion. HAHAHA.

[Allan Olesen]

Strapless will not prevent moving forward, if the floor is a bit slippery you will move. And I don’t think that but KNOW for a fact.

I repeat: The OP's problem is that the erg is moving backward. Not forward. Backward. Why is this so difficult to understand?

[Nomath]

Look to the Concept2 on slides and it is easy to see which body movements push the erg backwards.

[jackarabit]

Look to the Concept2 on slides and it is easy to see which body movements push the erg backwards.

Ez to see which body movements push the erg backwards (on slides). Very gentle ones. Which body movements of what force, velocity, or vector decenter the erg such that the slide rollers hit the cross rails of the track frames one end or t’other? Body movements at change of direction (catch and finish) ≠ ? Apparently the talent of producing corrective restoration of position by altering the stroke is very rare. I have never heard anyone say “Just walk it back.”

[Nomath]

Disregard the end stops. The video shows that when you move your body (i.e. center of mass) forwards, conservation of momentum implies that the erg moves backwards if not restricted by friction on the floor.
My guess is that the topic starter is moving more vigourously in the recovery, or friction on the floor is reduced.

[jackarabit]

Slides is analogous to boat in water in terms of frictional resistance. Static erg is more Converse Allstars on hardwood. In OP case, restriction or amplification of movement by friction with floor is a condition which can’t be whiffed away by special case. Charlie Chan say Take many blind men to touch elephant all over!

[jamesg]

The only fixed part of the erg that we can apply horizontal forces to, is the footrest. Either push or pull, both horizontal. Vertical forces can't move the machine horizontally, but of course once off the ground, friction is not the problem, and the machine will fly any way we force it to. So clearly we need to limit or better eliminate any vertical component of our forces. The purpose of which forces is to spin the flywheel using a roughly horizontal chain, not to fly to the moon.

Pushing on the footrest will tend to move the fan away from us, ie forwards in ergspeak. Pulling on the straps will move the erg backwards, towards the wall behind the erger. Both can be done intentionally, if we wish to move the machine without getting off. Intentional or not, the effect is the same.

So if the OP by backwards means movement of the erg towards the wall behind him, he must be pulling hard on the footstraps during recovery, probably just after release. A typical beginner fault, believing he has to take the next stroke asap. Who knows what other faults he might have? High ratings? Short pulls? High drag? Lifting the handle over his knees during recovery? Bringing the slide up to his heels? Following training plans designed for Olympic oarsmen rather than learning to row?

The simplest remedy is: don't do it. There 's plenty of time to get forward along the slide and all too soon we reach the frontstop anyway. We will then find ourselves effectively obliged to pull yet another very long hard exhausting stroke. A phenomenon well known to oarsladies and -men. We can't just sit there ad infinitum with the blades squared and in the air while the boat runs, the fish jump and the sun shines, much as we like to.

Going slowly forwards gives us time to think about the dreaded next hard and fast pull, so that we can do it at least from a comfortable and reasonably strong posture. Doing it in too much of a hurry by pulling the feet can only cause aches and pains if not injury. In any case why bother? The thing has enough slope and chain tension to do it for us, and a long hard meditated fast stroke with a slow recovery is worth at least two of any other type.

[jackarabit]

Both can be done intentionally, if we wish to move the machine without getting off. Intentional or not, the effect is the same.

First time for “Just walk it back” in my hearing. Bunny hopping the erg? Yeah, I can see that.

[cgrande]

Hi there.. Im trying to find the anti slip clear pads you have pictured.... do they protect wood floor and what company sells them. thanks so much

[RichBinAZ]

Has the OP tried turning the mat around?
It could be that over time the horizontal force applied to the mat has sheared it a bit and perhaps caused a "Carpet like nap" to form, which will tend to help the erg move one way more easily than another.

Speaking of forces, there is also a moment couple caused by the vertical distance between the chain and the foot pads. This provides a rocking movement where the rear digs in and the front lifts up on the drive (or is it the other way around??). This can cause the erg to creep off the mat, specially when pulling hard enough to lift your bum off the seat.

Fun engineering problem, but impressive that you can make the machine walk around the room - well done!!