Fly wheel stop before racing?

[GrantMatt]

When I go for a PB my routine is maybe a 5 min warm up, 1 min break while I plug in the distance/time, and then go for it.

However, this means when I start racing the fly wheel is still moving (albeit slowing down) and so the first few pulls would be easier then if it were completely stopped (which seems to take about 3 mins to stop dead). When it comes to 2km PB’s, a second or 2 advantage would be the difference between a PB or not for me.

I’m breaking no world records and if I’m only racing myself all that really matters is I’m consistent. But would like to know what others do; wait for the fly wheel to stop completely or not? Or perhaps just never thought too much about this…

PS: my 2km PB is 6.59 hence why I am wondering.

[Ombrax]

In group races I believe there's an RPM threshold set in the race computer that's used to determine if all the competitors' flywheels are essentially at rest (but not really). (this helps save time between starts if there's been a false start) I don't know if that's something that the organizers can change at will, or if it's typically hard-wired in, nor do I know what typical values are. However, the fact that the threshold exists tells us that perfectly normal and legal starts can be done before the flywheel is stationary.

I'm sure someone who's more familiar with racing will be able to provide more details.

[hjs]

When I go for a PB my routine is maybe a 5 min warm up, 1 min break while I plug in the distance/time, and then go for it.

However, this means when I start racing the fly wheel is still moving (albeit slowing down) and so the first few pulls would be easier then if it were completely stopped (which seems to take about 3 mins to stop dead). When it comes to 2km PB’s, a second or 2 advantage would be the difference between a PB or not for me.

I’m breaking no world records and if I’m only racing myself all that really matters is I’m consistent. But would like to know what others do; wait for the fly wheel to stop completely or not? Or perhaps just never thought too much about this…

PS: my 2km PB is 6.59 hence why I am wondering.

At races after a falls start we have wait, but not to a full stop. A home start is much faster to begin with, the rower does start, when racing, the computer does start and the rower reacts, which makes a clear difference. Thats the reason that 2k records need to be a race to be valid.

Re your problem, if you wait a few min. you have close to no gain left. Only for a 100m a moving fan should give some advantange. Your 2k would gain nothing.

[Carl Watts]

Only makes a big difference for the 100M so I use a moving flywheel below the monitor starting.

Before anyone jumps up and down and calls that cheating, I also do the 100M online as a race start so I loose over a second by the way that works. Firstly you have your reaction time at the start and any internet delay so the clock has already started before you pull.

If you just program in 100M to the monitor, the clock starts at the end of your first stroke giving you a big advantage.

If you want your best possible time, plug the 100M straight into the monitor, the difference would also be significant for the 500m and I'm not sure anyone racing at the top level would appreciate loosing even a second on the 2K.

[Citroen]

I don't know if that's something that the organizers can change at will.

With the old Venue Race software there were no external controls for stuff like that. The only control was the [START] button to set the "Sit Ready", "Attention", random pause, "ROW" going.

If folks want to practice racing starts with their PM4 or PM5 then it's possible to set-up a single competitor "wireless race" or "wired PC-less race" .

https://www.concept2.com/service/monito ... ireless-pc
https://www.concept2.com/service/monito ... pm5s#wired

That gives you the same "sit ready", "attention", "ROW" sequence.

Remember with a workout, you start rowing, the PM3/PM4/PM5 detects the stroke and starts the clock.
With a venue race, the clock starts, you react to "ROW" and start rowing.

That has a measurable difference on the final result, all other things being equal.

[Nomath]

As others have said already, the effect of an "early" start, after waiting only one minute, on the total time is negigible for a 2K time trial. I will show below that it is also hardly measurable for a 100m sprint.

If you would know the speed of the flywheel at the start, you can calculate its residual energy (E=½ I ω² ; ω is the angular speed ; I is the moment of inertia of the flywheel). If you divide this residual energy by the average power during your time trial, you get a very good estimate for the time advantage compared to a start at complete standstill.

Regarding physics, the ergometer itself is a fairly simple and predictable machine. If there is no externally supplied power, the rotation period of the flywheel increases linearly with time. The rate at which the rotation period (Tr) increases is proportional to the drag coefficient Cd and inversely proportional to the moment of inertia of the flywheel :
d(Tr)/dt = 2π * Cd/I
The moment of inertia is manufactured by Concept2 within very narrow tolerances. It is known to be close to 0.1 kg m².
The drag coefficient is related to the drag factor. For a drag factor of 120, the drag coefficient Cd = 0.000120 kg m²
Using these two characteristics and a very strong last stroke with a handle velocity of 3 m/s (this corresponds roughly to a 600W stroke!), I calculated the residual energy of the flywheel over time. This is shown in the figure below. Note that the residual energy is plotted on a logarithmic scale, because the loss in energy is very fast.



Now assume that you wait for 1 minute after your last stroke. At the finish of the last drive, the rotational energy of the flywheel was about 2 kJ. After waiting 1 minute the energy has reduced to only 8.5 J. A 2K PB of 6:59 corresponds to an average power of 305 W. So the time advantage would be roughly 8.5/304 = 0.03 second.

I guess that for a 100m sprint, your average power might be roughly 800W (i.e. 500m pace 1:16). Your time advantage is then 8.5/800 = 0.01 sec on a total time of roughly 15.2 sec. Still hardly measurable.

[GrantMatt]

As others have said already, the effect of an "early" start, after waiting only one minute, on the total time is negigible for a 2K time trial. I will show below that it is also hardly measurable for a 100m sprint.

If you would know the speed of the flywheel at the start, you can calculate its residual energy (E=½ I ω² ; ω is the angular speed ; I is the moment of inertia of the flywheel). If you divide this residual energy by the average power during your time trial, you get a very good estimate for the time advantage compared to a start at complete standstill.

Regarding physics, the ergometer itself is a fairly simple and predictable machine. If there is no externally supplied power, the rotation period of the flywheel increases linearly with time. The rate at which the rotation period (Tr) increases is proportional to the drag coefficient Cd and inversely proportional to the moment of inertia of the flywheel :
d(Tr)/dt = 2π * Cd/I
The moment of inertia is manufactured by Concept2 within very narrow tolerances. It is known to be close to 0.1 kg m².
The drag coefficient is related to the drag factor. For a drag factor of 120, the drag coefficient Cd = 0.000120 kg m²
Using these two characteristics and a very strong last stroke with a handle velocity of 3 m/s (this corresponds roughly to a 600W stroke!), I calculated the residual energy of the flywheel over time. This is shown in the figure below. Note that the residual energy is plotted on a logarithmic scale, because the loss in energy is very fast.



Now assume that you wait for 1 minute after your last stroke. At the finish of the last drive, the rotational energy of the flywheel was about 2 kJ. After waiting 1 minute the energy has reduced to only 8.5 J. A 2K PB of 6:59 corresponds to an average power of 305 W. So the time advantage would be roughly 8.5/304 = 0.03 second.

I guess that for a 100m sprint, your average power might be roughly 800W (i.e. 500m pace 1:16). Your time advantage is then 8.5/800 = 0.01 sec on a total time of roughly 15.2 sec. Still hardly measurable.

Thankyou for all responses. But your post Nomath is next level. I was expecting a few people say they do wait for the fly wheel to stop, and others don't, but to get an answer based on physics + a graphical representation puts the issue to dead. I wont lose sleep over the 0.03 advantage I have been giving myself

[KeithT]

I was just going to give the generic answer that I wait for fly wheel to stop before doing TTs but didn't think the advantage was too big if you didn't and that was just proven.