Formula for calculating Average Split (Avg. Min/500M) for rowing machines

Maintenance, accessories, operation. Anything to do with making your erg work.
Post Reply
dungnguyen
Paddler
Posts: 2
Joined: March 21st, 2024, 1:04 am

Formula for calculating Average Split (Avg. Min/500M) for rowing machines

Post by dungnguyen » March 25th, 2024, 1:36 am

Hi guys,

I'm a very-new member and hope that I can learn much from people. I have some questions

1.Is there a time limit for Stroke Time?
For example, I made 3 strokes as below
S1: This takes 4 seconds
S2: This takes 10 seconds
S3: This takes 3 seconds

There are 3 approaches
A1: The Total time will 4 + 10 + 3 = 17 seconds. No any strokes skipped
A2: S2 is greater than a limit so that it will be skipped. The Total time will 4 + 3 = 7 seconds
A3: S2 is greater than a limit so that it will be the limit. For example the limit is 5/ The Total time will 4 + 5 + 3 = 12 seconds

Which one is correct? or If there is another option, please tell me

2.For formula to calculate Avg. Split
It is Avg. Split = (500 / Distance) * Time

Time here will be the Total time I have mentioned in the question above, right?

User avatar
Citroen
SpamTeam
Posts: 7957
Joined: March 16th, 2006, 3:28 pm
Location: A small cave in deepest darkest Basingstoke, UK

Re: Formula for calculating Average Split (Avg. Min/500M) for rowing machines

Post by Citroen » March 25th, 2024, 5:47 am

Stroke rate is a secondary metric. Some cheapo rowing machines use that as the primary (only) measure.

The power you get per stroke is what the PM2, PM2+, PM3, PM4 or PM5 is measuring. It's all measured in watts then the other units are derived from that by the maths that the PM is doing.

https://eodg.atm.ox.ac.uk/user/dudhia/r ... meter.html

JaapvanE
10k Poster
Posts: 1117
Joined: January 4th, 2022, 2:49 am

Re: Formula for calculating Average Split (Avg. Min/500M) for rowing machines

Post by JaapvanE » March 25th, 2024, 6:59 am

dungnguyen wrote:
March 25th, 2024, 1:36 am
1.Is there a time limit for Stroke Time?
Yes, based on my experiments, when the flywheel has decelerated enough and it is around 6 seconds since the last drive, the PM5 (and most of its predecessors) will consider it a pause. So 10 seconds per stroke is way too long.
dungnguyen wrote:
March 25th, 2024, 1:36 am
2.For formula to calculate Avg. Split
It is Avg. Split = (500 / Distance) * Time
In theory, yes. But ErgData and the C2Logbook will nicely calculate it for you, so why bother.

JaapvanE
10k Poster
Posts: 1117
Joined: January 4th, 2022, 2:49 am

Re: Formula for calculating Average Split (Avg. Min/500M) for rowing machines

Post by JaapvanE » March 25th, 2024, 7:17 am

Citroen wrote:
March 25th, 2024, 5:47 am
It's all measured in watts then the other units are derived from that by the maths that the PM is doing.

https://eodg.atm.ox.ac.uk/user/dudhia/r ... meter.html
I think you interpret Annu's work the wrong way. The power formula links the linear and rotational systems in a linear erg. But it doesn't state that one should first calculate power and then one can calculate average speed across the stroke.

Although I have no insight in the inner workings of a PM5, I do know how we resolved this translation in OpenRowingMonitor, and why we did it. The route to calculate the power and then use that to calculate other dependent metrics tends to be cumbersome and actually not too robust against noise. The main issue is that Power is only defined well at the end of a stroke, making such an approach vulnerable to errors in stroke detection. When you use his formula's to rewrite them to robust math, you get nice simple equations like
u = (k/C)^1/3 * w
where u is the average linear velocity, k the dragfactor, C the magic constant and w the average rotational velocity. As w is an average across the entire stroke for all instantaneous w's, small errors in stroke detections will not affect it much. As these instantaneous w's are also needed for the force curve, they are to be generated anyway. Please note, this also opens the door to instantaneous linear velocity.

iain
6k Poster
Posts: 927
Joined: October 11th, 2007, 6:56 am
Location: Reading, UK

Re: Formula for calculating Average Split (Avg. Min/500M) for rowing machines

Post by iain » March 25th, 2024, 9:24 am

JaapvanE wrote:
March 25th, 2024, 6:59 am
dungnguyen wrote:
March 25th, 2024, 1:36 am
1.Is there a time limit for Stroke Time?
Yes, based on my experiments, when the flywheel has decelerated enough and it is around 6 seconds since the last drive, the PM5 (and most of its predecessors) will consider it a pause. So 10 seconds per stroke is way too long.
dungnguyen wrote:
March 25th, 2024, 1:36 am
2.For formula to calculate Avg. Split
It is Avg. Split = (500 / Distance) * Time
In theory, yes. But ErgData and the C2Logbook will nicely calculate it for you, so why bother.
I think it depends upon what you are rowing. On "Just Row" then the monitor will ignore the time from the shut down to the next stroke, but for a distance or time piece / interval then I believe that the clock keeps running for much longer although it may stop recording metres after 6S or so. THat said, rowing below 6SPM is very rare, so unlikely to be a concern.
55, lightweight in pace, trying to get back to Lwt by gravity. Currently training 3 times a week after a break to slowly regain the pitiful fitness I achieved a few years ago. Free Spirit, come join us http://www.freespiritsrowing.com/forum/

dungnguyen
Paddler
Posts: 2
Joined: March 21st, 2024, 1:04 am

Re: Formula for calculating Average Split (Avg. Min/500M) for rowing machines

Post by dungnguyen » March 26th, 2024, 6:50 am

JaapvanE wrote:
March 25th, 2024, 6:59 am
dungnguyen wrote:
March 25th, 2024, 1:36 am
1.Is there a time limit for Stroke Time?
Yes, based on my experiments, when the flywheel has decelerated enough and it is around 6 seconds since the last drive, the PM5 (and most of its predecessors) will consider it a pause. So 10 seconds per stroke is way too long.
dungnguyen wrote:
March 25th, 2024, 1:36 am
2.For formula to calculate Avg. Split
It is Avg. Split = (500 / Distance) * Time
In theory, yes. But ErgData and the C2Logbook will nicely calculate it for you, so why bother.
Thanks you, it helped me a lot

Post Reply