Changing DF during BikeErg race

[MudSweatAndYears]

Prior to doing a time trial over a C2-recognised race distance (e.g. 1k or 4k, etc) one is asked to confirm calibration. This calibration is required for achieving verification on the C2 ranked result. I was under the impression that this verification would be frustrated in case the damper setting would be changed during the workout. However, recently I noticed that this appears not to be the case: the piece still gets verified in the ranked results even after changing the DF during the workout, as long as the calibration was carried out as instructed by the PM5 monitor.

It appears to me that changing the DF during say a 1k race can be highly beneficial: one can start at a low DF to get the flywheel quickly spinning, and than increase the DF so that too high spinning rates are avoided. (Just like the use of a derailleur on a road bike.)

Now my question is: would this be considered cheating? Or is this entirely acceptable (and might people actually be doing this already)?

[Nomath]

Cheating who? Yourself or others?

What you suggest is not a smart way of cheating others but yourself. If the erg has been 'calibrated' on a low Drag Factor, it has no way to find out that you changed the calibration during the exercise in other ways than by the damper setting (damper settings are part of the calibration procedure and a change will also change the DF-value). The power measurement goes approximately as : P = DF * ωm³ , in which ωm is the average angular velocity of the flywheel. Changing to a higher DF by other means than the damper setting will reduce the angular velocity but not the DF value used in the measurement, hence the 'measured' power and pace and distance are lower than your actual power input.

The smart way of getting to inflated power, pace and distance figures is to calibrate at a high DF and change to a low DF during the run by dropping a towel over the flywheel cage.

[MudSweatAndYears]

The smart way of getting to inflated power, pace and distance figures is to calibrate at a high DF and change to a low DF during the run by dropping a towel over the flywheel cage.

That would be straight cheating. Let''s not go there.

This thread is not about corrupting the power measurements, and not about inflating power readings. It's about getting more power out of your body by keeping the cycling cadence close to optimal. As the BikeErg's flywheel cage is fitted with an angle detection on the damper lever, adjusting the damper setting during a race can be put to use in optimising your cadence without causing any corruption in the power measurements. As I said, this is akin to using a derailleur on a road bike. But still, the question remains: would this be considered legal for BikeErg workout ranking purposes?

[gvcormac]

It is my understanding that, while it doesn't offer any tangible advantage, DF changes are generally prohibited in rowing races. I'm not sure about bike races, but I would not be surprised.

The DF has no effect on the inertial mass of the bike, and little effect at low speeds, so starting at a lower DF won't help much to get the mass moving. And even if it did, the PM5 would give less credit for the faster flywheel.

Maybe there's some second-order effect but I'd think that it'd be a better use of your hands to pull on the handlebars to increase your pedal force than to fiddle with the damper.

[MudSweatAndYears]

The DF has no effect on the inertial mass of the bike, and little effect at low speeds, so starting at a lower DF won't help much to get the mass moving. And even if it did, the PM5 would give less credit for the faster flywheel.

That's a valid point. To overcome the drag on the flywheel, lowering the drag factor acts as lowering the gear ratio. But when it comes to overcoming the flywheel inertia, lowering the drag factor has zero effect. So I should tamper my expectations on the positive effect of lowering the drag factor at the start of a sprint.

It is my understanding that, while it doesn't offer any tangible advantage, DF changes are generally prohibited in rowing races. I'm not sure about bike races, but I would not be surprised.

Right. That should carry over to bike races I guess. Thanks! (It leaves me puzzled though why the PM5 software does validate the result even when a damper lever position change is detected during the race.)

[mementobeansbeef]

I noticed that changing the damper setting (DF) mid-workout doesn't mess up the verification process. In fact, it can even be a smart move! Starting with a lower DF to get that flywheel spinning and then cranking it up to avoid crazy-high spinning rates sounds like a legit strategy, just like using a derailleur on a road bike.

[JaapvanE]

It is my understanding that, while it doesn't offer any tangible advantage, DF changes are generally prohibited in rowing races. I'm not sure about bike races, but I would not be surprised.

Right. That should carry over to bike races I guess. Thanks! (It leaves me puzzled though why the PM5 software does validate the result even when a damper lever position change is detected during the race.)

AFAIK, the PM5 on a bike sees the damper position directly via a variable resistor in the cage, where in a rower we observe it via the slowing of the flywheel. Older PM's used to average acros quite some strokes, creating a considerable advantage for over 150 meters. Newer PM's use another approach and the change in damper is detected within 3 strokes. So this rule might be a relic of the old days.

[CaseyClarke]

Looks like someone didn’t read the rules!

5. There is no required damper setting. You are free to choose the setting you prefer and you may change the setting during the piece as long as it is done by the person using the machine. Learn more about damper settings!

As for starting on a low drag, then changing to a high/er one on a sprint?! No! Works better the other way around. When you start on a low drag on a sprint it takes far longer to get up to pace compared to starting on a higher one, so you lose too much in the first split. Actually better to start high, then drop it down part way into the sprint if you can do that without affecting the pace. Every tenth is important in a short sprint.

[MudSweatAndYears]

5. There is no required damper setting. You are free to choose the setting you prefer and you may change the setting during the piece as long as it is done by the person using the machine.

Ah, right! That settles it. Thanks!

As for starting on a low drag, then changing to a high/er one on a sprint?! No! Works better the other way around. When you start on a low drag on a sprint it takes far longer to get up to pace compared to starting on a higher one, so you lose too much in the first split. Actually better to start high, then drop it down part way into the sprint if you can do that without affecting the pace. Every tenth is important in a short sprint.

You are right (once more!). This counter-intuitive effect must be related to the fact that when starting from a stationary flywheel the PM5 doesn't measures the total wattage put into the flywheel, but only the wattage used to overcome the air drag. The wattage that goes into overcoming the flywheel inertia is ignored. Lower drag factors increase the contribution of inertia over drag, which exacerbates the effect.

I experimented with low and high drag factors in 9 sec sprints (starting from stationary flywheel):

DF = 57
0-3 sec: 19 m
4-6 sec: 33 m
7-9 sec: 38 m
total: 90 m

DF = 158
0-3 sec: 26 m
4-6 sec: 38 m
7-9 sec: 39 m
total: 103 m

A difference of 12 m in just the first six seconds. And I haven't maxed out the drag factor yet. I will experiment a bit more, further increasing the drag factor, and testing if manually reducing the drag factor after the start causes significant loss in speed (reading the rules, equipping the lever with an extension is not allowed, so you have to bend down significantly). To be continued...

[johnlvs2run]

I experimented with low and high drag factors in 9 sec sprints (starting from stationary flywheel).

How did you do 9 second sprints, and get the meters to show up for every 3 seconds on the pm5 monitor?

[MudSweatAndYears]

I experimented with low and high drag factors in 9 sec sprints (starting from stationary flywheel).

How did you do 9 second sprints, and get the meters to show up for every 3 seconds on the pm5 monitor?

I programmed a 3 second intervals (zero rests) BikeErg workout in the ErgZone app.