Anyone know why this doesn't exist?

[Dutch]

Df on the bike erg in a recent 500m sprint had a big effect for me. I did one at 110 df and got 42.9, I struggled the last 150 meters as I had blown out. I lowered it to 100df the next time out and got 42.8 and the last 150 again I started to struggle but I had a little more zip as the df was slightly lower.
I did one Friday and did it at 120df, having done alot of strength training and 10ks rides with the df on 120 to 130 and my legs died at 150 and by 50m to go I felt like I had lead on my feet.
For me, 130 df for on bike is brilliant for 200m, but not much more.
As well, df over 160 has an upper limit of about 150m flat out and that's it my legs are slowing, a 1k ride and I am down below 60 rpm.
Some of the top guys on the concept bike erg here are doing 100 and 200k on df 120 with an rpm of about 80 for about 3 to 6 hrs. I do 10k with an rpm of around 66 average. I flirt now and then with a 20k on a lower df of 80 but that's it.
The df for me on the bike is a resistance level, not a gearing.

[emar]

This is more for posterity (and for anyone lurking), since I probably will never have the time to actually make it myself:

I'm imagining something like an Raspberry PI connected to an actuator that directly attaches onto the flywheel housing and over the DF adjustor that mechanically moves the lever to the desired DF by detecting the current DF using the C2 SDK, with a supporting Android app that allows pre-programming simulated terrain and/or intervals.

Shout out to JaapvanE for possessing literacy. I'll rapidly respond to everyone else without using names.

Manually adjusting the drag factor during a workout disrupts the workout; this is undesirable. Automatically adjusting it also allows for a gradual adjustment over time. This is desirable.

A device would increase the cost and complexity of maintenance; that's why I said "aftermarket" and "I know C2 prioritizes simplicity of maintenance, so I totally understand why C2 doesn't produce one (or come standard), but why hasn't anyone else made one?"

As far as reasons, dynamically adjusting the drag factor would allow for a mimicking of different terrain, as C2 states on their page on damper setting for the SkiErg:

From Damper Setting 101:

Many people confuse damper setting with intensity level or resistance. Instead, the intensity of your workout is controlled by how much you use your core, legs and arms to move the handles—in other words, how hard you pull. This is true regardless of where the damper lever is set: the harder you pull, the more resistance you will feel. Because our SkiErgs use wind resistance (which is generated by the spinning flywheel), the faster you get the wheel spinning, the more resistance there will be.

Think about skiing on snow. Regardless of whether you are skiing in fast or slow conditions, you will need to increase your intensity and apply more force to go faster. The difference is in how it feels to go faster in different conditions. Increasing your speed in fast conditions requires you to apply your force more quickly. Increasing your speed during slow conditions also requires more force, but the speed at which you apply the force will be slower over the course of the pull.

At a damper setting of 1–4, the SkiErg feels like faster snow conditions, flats and down hills; at the higher numbers, the SkiErg feels like skiing in slow conditions or uphill. Regardless of the setting, you will need to increase your effort to increase your intensity.

The goal would be to mimic the conditions of the sport, which would be primarily for the SkiErg and BikeErg, not the RowErg. I don't think this hypothetical device would necessarily meaningfully apply to the RowErg, which is why I said "It seems like it'd be a perfect match for both the BikeErg and the SkiErg (probably also the RowErg, but rowing up and down a mountain doesn't seem as apt)."

I personally would still use such a device on the RowErg for gradually switching between low DF high SPM workouts and high DF low SPM workouts. The answer of why I'll leave as an exercise to the reader.

I honestly don't care about logging my workouts, but this is probably the real reason it doesn't exist. Namely, that it invalidates ranking the workout.

Cheers!

[JaapvanE]

I'm imagining something like an Raspberry PI connected to an actuator that directly attaches onto the flywheel housing and over the DF adjustor that mechanically moves the lever to the desired DF by detecting the current DF using the C2 SDK, with a supporting Android app that allows pre-programming simulated terrain and/or intervals.

OpenRowingMonitor can calculate DF and can be connected to Zwift. We can't recieve BT-commands (yet?), but the new version we are working on has the essentials for intervals and is pretty accurate in measuring distance on a C2 rower (currently 0.3% off from the PM5). I have the schematics and it is based on a simple prefab board. Adding a small controll loop driving an actuator is doable, but I have no experience in driving actuators from a Pi.