Concept2 Forum

I am looking for some information and insight into drag factor. I have read on the forums and the C2 website and understand the difference between the damper settings. (3/4 vs. 10). I even have the chart which shows the different drag factor equivalents for the different models of ergs relative to a Model B.

I am (re)starting my indoor rowing journey for fitness and am enjoying it immensely.

I own a model B erg (love it!!) with a PM5.
I have installed the flywheel damper extension ring.
The monitor is running the latest updates:
PM5 firmware version 169
Hardware version 634
set to model B/C.

When using the monitor to check my drag factor - I get a drag factor of 114. I am HWT.

When I am using the erg to do workouts (Asensei) the drag factor can vary as much as +/- 2 to 5 or more.
I was under the assumption of "set it & forget it" and was not expecting the drag factor to vary.

The erg does not vibrate (on a concrete floor), nor does the flywheel damper extension ring seem to shift.

dust/crud ??

Any insight would be much appreciated. thanks !!

Maximum rating on the erg is about 40, which gives us 1.5s for a complete stroke and so just under half, or 0.6-0.7s for the pull.

Drag is set so that at training ratings (18 to 23) the pull time is the same: 0.7s or a little lower, when pulling full length, full force. That's what we do to train, since it's the type of stroke that can be called rowing.

This for everyone; so if you are big, young and strong and can pull hard, you can set high drag, say 130-140.

If old, weak and lazy like me, set drag to around 90 or less. I pull at about 1.9 m/s and 40 kg; height now 185, 80kg. But in any case check your pull force, length and speed, using Ergdata.

High force and high pull speed mean we work hard. Since we all have legs strong enough to climb stairs, why not. It may well be unpalatable to start with; so keep the rating low. But never compromise your stroke.

Variations seen for DF may depend on the impulse stream from the flywheel (if it's like the C I have). The C gives an impulse every 30mm travel, so 40 or 41 impulses for 120 cm travel. But if the travel was only 119 cm, there could be 39 impulses, 2.5 to 5% difference, and this may cause a variation in the drag reading; but not in the real drag.

It does change a bit over the extremes of rating vs pace.

Also it slowly just continually drops over time with dust buildup.

Mine can be 124 or 125 without changing a thing.

There are also way more flywheel pulses coming off the model D and the flywheel design is totally different so I would expect greater accuracy and consistency, things move on. The Model B is a bit old now.

I get some drag variation in my D/PM5. When I take time to set it its 145. Looking at my logs various sessions get recorded at 143 - 147 without me adjusting the lever. Part of the variation comes when I switch on the fan that I use for cooling. It sits right next to the cage (on the left of the erg) and is aimed at my front. Presumaly affects airflow through the cage in some minor way. Thing is though, even after all these years I'm not a good enough erger to notice the difference of just 3 or 4 on the drag factor so I don't bother about it at all. I've found differences of 10 or more are very noticeable and do affect my performance....

Drag is recalculated on every stroke.
It's sensitive to clogging in the fan cage, elevation, temperature and local air pressure.

So a little bit of hysteresis can be expected but it's mostly self calibrating.

Cleaning the fan cage, including the magnets and hall-effect sensor may make things more stable.

MPx wrote: ↑

December 6th, 2021, 7:18 pm

Part of the variation comes when I switch on the fan that I use for cooling.

I noticed this as well, so I located the fan to blow on me, but not the wheel. I also had the machine pretty close to a wall (on the wheel, or right, side) when I first set it up in the room. The turbulence between the wall and machine made it vary quite a bit, so I moved it about 2' away and the DF was much steadier.