Investigating Race Starts

From the CRASH-B's to an online challenge, discuss the competitive side of erging here.
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Recess
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Investigating Race Starts

Post by Recess » March 7th, 2022, 8:43 am

I've been asked a LOT about making a video about Race Starts on my RowAlong channel. Here is my take on them.

https://youtu.be/D8keQc3vQZA

I'll say now, I went into this thinking I knew the answer. And spoiler alert - I was wrong! You may spot this by what I say as I lead into the first test.

Anyway. I go through three ways to start off a 100m row - and find out which was works best FOR ME. And that's the key here. You need to try out different starts - be honest, and then work out what's best for you.

After these 100m rows, I then go into how I would use this knowledge to help the start of a 2000m row - and how I would pace that row.

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Carl Watts
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Re: Investigating Race Starts

Post by Carl Watts » March 7th, 2022, 11:49 am

All I know is a "Race Start" is no good for a 100m PB full stop.

You lose up to 2 seconds using RowPro online for a "Race Start" as opposed to just setting up 100m directly on the PM5 due to all the start delays plus the way the PM5 starts the "stopwatch".

100m "Race Start" you have the stopwatch start before your even moving so there is the internet latency plus your reaction time plus the time it takes to get to the end of the first drive. You easily lose 1.5 seconds. This is massive in a 100m and many would argue you wouldn't even want to lose this even in a 2000m row.

100m programed on the monitor removes all the delays, the stopwatch doesn't appear to start until the end of the first drive, or at least you defiantly already moving before the stopwatch starts, there is no other way the PM5 can know you have started.
Carl Watts.
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Recess
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Re: Investigating Race Starts

Post by Recess » March 7th, 2022, 11:58 am

Yeah, that's why I was nowhere near RowPro or any proper race software for these tests. And the flipside to what you're saying is the people who time their first stroke just enough before the start that they don't miss the start at all, but not to much that it's a false start. It was really interesting watching all the starts for the 500m events on the recently WVRIC for that reason.

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Re: Investigating Race Starts

Post by Dutch » March 7th, 2022, 12:50 pm

Interesting video with trying all the different starts. I to have tried all the different types of starts and come to the same conclusion that full starts are probably the best for the average person. You are getting full power in a long stroke.
If you are not bulky and full of fast twitch fibres, quick starts are not going to happen the same as a 14 second 100m person. Some people are not big built and can start quick yes, but they are full of fast twitch fibres, the average person is somewhere in between, give or take a few percent.
I some times program in 100m and just pull the first 5 strokes and it is always the same give or take 1 tenth, practice after practice does not take chunks off, lol not for me anyway.
Age 52, 186cm 82kg

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Re: Investigating Race Starts

Post by Recess » March 7th, 2022, 1:18 pm

I do wonder if there's literally a terminal velocity for these things. One of the next videos I want to make will hopefully unpack this a little further. As being when I was testing machines, by 100m was 17.6 for both, and then all of these tests were between 17.6 and 17.8 - it seems like I've hit my speed.

So I'm looking forward to looking at whether that can be improved!

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Re: Investigating Race Starts

Post by Dutch » March 7th, 2022, 1:46 pm

There is probably a formula for it lol. speed times weight times height etc!
I think the only way for someone to improve their sprint dramatically (100m) is probably strength training. Stay the same body weight, but go up in strength, rather than just gain bulk I mean.
Bulking up 2 or 3 stone would probably have an effect. But if you are a light weight and wish to remain there then strength is the only key to be able to unlock any big further improvements I feel. Say 0.5 secs or maybe even a whole second.
Go from squatting 60 kilos to 110 kilos for 5 reps or so and there surely would be some difference. Same for other parts of the body that effectively help with rowing.
Age 52, 186cm 82kg

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Re: Investigating Race Starts

Post by GlennUk » August 5th, 2022, 6:22 am

Recess wrote:
March 7th, 2022, 1:18 pm
I do wonder if there's literally a terminal velocity for these things. One of the next videos I want to make will hopefully unpack this a little further. As being when I was testing machines, by 100m was 17.6 for both, and then all of these tests were between 17.6 and 17.8 - it seems like I've hit my speed.

So I'm looking forward to looking at whether that can be improved!
This is quite interesting, i plan to try to improve my 100m PB shortly, so acknowledging the point that the start is absolutely critical to getting the best time, i thought that the 'best' approach would have been the 1/2, 3/4, 1/2 approach.

Something not considered is the DF, which will impact on the rowers ability to pull a 'quick' stroke initially, historically i had set my DF to c.180 from memory, but when i set my all time PB in Nov last year, it was set to 160.

Makes me think that when i train for this in a few weeks that not just the approach to the start in terms of stroke length, but also DF will have a significant impact on the process.

For info, im a HWM but a small one at only c. 89Kgs and 1.8m tall.
Age 61, on 2/01/22 I rowed 115,972m 11hrs 17m 57s and raised £19k for https://www.havenshospices.org.uk/ Thanks for all the support

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Re: Investigating Race Starts

Post by JaapvanE » August 5th, 2022, 7:55 am

Carl Watts wrote:
March 7th, 2022, 11:49 am
100m programed on the monitor removes all the delays, the stopwatch doesn't appear to start until the end of the first drive, or at least you defiantly already moving before the stopwatch starts, there is no other way the PM5 can know you have started.
Carl,

For what I understand, it seems to depend on your flywheel velocity. I can compare the results directly with OpenRowingMonitor, and the PM5 is sometimes late to the party (with ORM 1 second ahead of the PM5). In the bluetooth specifications, it says the PM5 has a state which is called "STROKESTATE_WAITING_FOR_WHEEL_TO_REACH_MIN_SPEED_STATE", where nobody besides C2 knows what the speed should be. However, it does suggest that such a state precedes the normal rowing state (and thus metrics like the timer are triggered only after this transition is made). I haven't been able to stay below this speed long enough to test this behaviour.

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Re: Investigating Race Starts

Post by Citroen » August 5th, 2022, 8:57 am

Have you all looked at the "Racing" option? You can simulate real "Sit ready", "Attention", "ROW" starts with that.

Main menu > More options > Racing > Create race > Start race
(It can have from 1 to 8 PM5s connected.)

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Re: Investigating Race Starts

Post by gvcormac » August 5th, 2022, 9:02 am

My understanding is that the PMx monitor underestimates the power of your first several strokes, because it uses some default parameters for drag. So in trying to optimize your performance, you are actually trying to do two things, which may be incompatible: maximize your actual energy output, and maximize the extent to which it is captured by the PMx.

More research is needed to figure out which is best. I wonder if it depends on how quickly you can exceed whatever the default parameter settings give you. It is not clear whether this is done by pulling more strokes, or by getting more velocity on the first stroke. This may well depend on your stroke as well as the drag factor setting.

Personally, I hate trying to wrangle the machine and if I can do just as well without, I won't. I'll certainly try it out.

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Re: Investigating Race Starts

Post by gvcormac » August 5th, 2022, 9:09 am

Recess wrote:
March 7th, 2022, 11:58 am
Yeah, that's why I was nowhere near RowPro or any proper race software for these tests. And the flipside to what you're saying is the people who time their first stroke just enough before the start that they don't miss the start at all, but not to much that it's a false start. It was really interesting watching all the starts for the 500m events on the recently WVRIC for that reason.
In track events, any movement prior to 0.1sec after the gun is considered a false start.

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Re: Investigating Race Starts

Post by JaapvanE » August 5th, 2022, 10:41 am

gvcormac wrote:
August 5th, 2022, 9:02 am
My understanding is that the PMx monitor underestimates the power of your first several strokes, because it uses some default parameters for drag. So in trying to optimize your performance, you are actually trying to do two things, which may be incompatible: maximize your actual energy output, and maximize the extent to which it is captured by the PMx.
Your completely right on that one, for more reasons than one. Two things happen in the PM5 in the first stroke: the first indeed is that the PM5 doesn't have a dragfactor yet, so it assumes a default for the time being. I haven't detected if it corrects this retroactively once the first valid dragfactor comes in (which could be done technically). As such correction tends to be in the centimeter range, one wouldn't be able to detect it with layman's equipment, but you would notice it in short sprints in a 100 meters. However, everybody has the same handicap, although my estimate is that the PM5 assumes a default DF of 120, so when you row your sprint on a DF of 225, you might get a disadvantage.

Another thing that happens, especially at the start, is that C2 uses incomplete formula's for its power calculation (and thus for speed and distance), to keep things simple. University of Ulm detected this when they hooked up a robot to the C2. The PM5 assumes that the power can be calculated using the cube law based on the flywheel speed and uses this to calculate linear speed and distance (i.e P = k*ω^3 = c * u^3). This works well when the flywheel speed is more or less the same at the same point in the stroke. However, the complete formula is P = (Inertia * ( dω / dt ) * dθ + k * ω^2 * dθ) / t, which can be transformed in P = k * ω^3 + Inertia * ( dω / dt ) * ω. The second part of this formula has an additional factor "Inertia * ( dω / dt ) * ω" is especially important at the start, as dω /dt (i.e. angular acceleration) is considerable but isn't taken into account in the PM5's calculations. As the team in Ulm concluded, the effect is that the PM5 "rewards" stroke-to-stroke consistency and really "punishes" stroke-to-stroke inconsistency, but also is pretty bad at estimating the speed and distance when the flywheel still accelerates from stroke to stroke (i.e. the first three to five stroke at starts).

As I see it, to be as efficient as you can on the PM5, you need to get to a steady flywheel speed as soon as possible. So exploding at the start to get that flywheel up to speed would be most effective from theory. Whether people can do that, I guess it would depend on the person holding the handle....

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Re: Investigating Race Starts

Post by Recess » August 5th, 2022, 12:43 pm

Blimey. That’s a lot of maths…

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Re: Investigating Race Starts

Post by JaapvanE » August 5th, 2022, 4:15 pm

Recess wrote:
August 5th, 2022, 12:43 pm
Blimey. That’s a lot of maths…
Sorry about that. Can't help it, it is a occupational related insanity.....

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Re: Investigating Race Starts

Post by GlennUk » August 8th, 2022, 2:50 am

JaapvanE wrote:
August 5th, 2022, 10:41 am

As I see it, to be as efficient as you can on the PM5, you need to get to a steady flywheel speed as soon as possible. So exploding at the start to get that flywheel up to speed would be most effective from theory. Whether people can do that, I guess it would depend on the person holding the handle....
That would also seem logical from a subjective perspective also, i.e. the fastest time is achieved when the speed is higher for longer, assuming of course that having achieved max speed that it can be maintained for the distance required.

The key is how to achieve max speed of the flywheel as quickly as possible. I had always assumed that it was likley to be a combination of short strokes, and using a 'relatively' high DF, which is what i had always tried based on typical responses on forums such as this about race starts, this thread has made me wonder how best to achieve the max as quick as possible.
Age 61, on 2/01/22 I rowed 115,972m 11hrs 17m 57s and raised £19k for https://www.havenshospices.org.uk/ Thanks for all the support

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