Calibration of Old Monitor/Erg

[lukearyan]

My erg is an old Model B. I think my monitor is not calibrated right. It seems about 20 seconds fast (per 500) compared to the local gym Model D. Is there a way to calibrate my monitor?

[Citroen]

The monitor is self-calibrating.

The only monitors with any controls are PM3s and PM4s which can be configured for either model B/C or model D/E. They produce some very strange results when that setting is wrong.

The model B is very sensitive to position - if it's too near a wall it will get odd results. It's also not directly comparable to a model D without things like the speed ring and if the chain isn't on the 14 tooth sprocket. So there's a certain amount of comparing apples with oranges when you try to match a model D workout in a public gym to a model B workout done at home.

[Bob S.]

The model B is very sensitive to position - if it's too near a wall it will get odd results. It's also not directly comparable to a model D without things like the speed ring and if the chain isn't on the 14 tooth sprocket. So there's a certain amount of comparing apples with oranges when you try to match a model D workout in a public gym to a model B workout done at home.

The pace is supposed to be equivalent and not dependent on the gearing or air-shielding. As far as the monitor is concerned the only difference between a B and a D is the physics of the differing flywheels. When I switched from a PM to PM3 on my model B I found no difference in the results. Of course the new PM3 was configured for model B flywheel.

Bob S.

[Citroen]

The pace is supposed to be equivalent and not dependent on the gearing

So you're saying that the 14-tooth is identical to the 15-tooth. That doesn't make sense. If the damping and chain speed are kept constant then for the same amount of chain movement you're getting 15/14ths or 14/15ths of the rotational velocity - that must make some difference.

[Carl Watts]

Row a 30 minute piece on the monitor and also use a stopwatch. As long as the two are within a second, there is nothing wrong with the monitor as far as it's internal crystal timing is concerned.I presume you are using a PM1. It would also pay to put new battereis in at and give it a proper reset.

As already pointed out the monitor is self calibration in terms of the drag factor, which you can adjust by moving the chain sprocket you are using.

[Bob S.]

The pace is supposed to be equivalent and not dependent on the gearing

So you're saying that the 14-tooth is identical to the 15-tooth. That doesn't make sense. If the damping and chain speed are kept constant then for the same amount of chain movement you're getting 15/14ths or 14/15ths of the rotational velocity - that must make some difference.

No. That is not what I am saying. The pace displayed by the monitor is based on how fast the flywheel slows down and is independent of how it is speeded up - gears, chain movement, whatever.

Since the B and D have different flywheels, the monitors used on them have to have different programming. Any major discrepancy between the results on a B and on a D is most likely due to a monitor with the wrong program and we have seen a number of instances of that on this forum and you have pointed out what needs to be done to correct that.

In regard to the B and position, as you said yourself, the monitor is self-calibrating, so the damping and any other restrictions of airflow, like nearby walls, are already compensated for.

Bob S.

[Citroen]

In regard to the B and position, as you said yourself, the monitor is self-calibrating, so the damping and any other restrictions of airflow, like nearby walls, are already compensated for.

Bob S.

Except with the PM1 which didn't calculate drag on every stroke so was more sensitive to external effects. All models don't create sensible numbers if the flywheel is too close to a wall and has restricted inflow.

[Bob S.]

Except with the PM1 which didn't calculate drag on every stroke so was more sensitive to external effects. All models don't create sensible numbers if the flywheel is too close to a wall and has restricted inflow.

O.K. I remember something about that now. Is that the original reason that you weren't allowed to change the damper in the middle of a race?

Bob S.

[Citroen]

O.K. I remember something about that now. Is that the original reason that you weren't allowed to change the damper in the middle of a race?

Correct.