A discussion about rowing "SPI"

[ampire]

Its was my goal to generate some constructive dialog and gather a broader perspective on this topic and that has certainly been the case (with added humor to boot).

I can definitely echo what Ampire said...

Personally, a year ago I was getting some decent time trial results but my every day training was often in the 28-32 SPM range and my SPI was pretty poor for those.

I spent the past couple months R18-22 and the result is I think I am more efficient and probably have better form because of it. Now I am roughly doing the same paces I was doing a year ago but at R20 instead of R28 for example.

This has been my exact experience as well... When I started in 2017, my rowing was pretty much r27+ all the time. Now, after 4 years, I routinely get better results at much lower rates (r18 to r24). Its for this reason why I record SPI in my logbook. Its been a helpful yardstick in measuring my ability over time.

I wonder how well I can re-adapt to high rating again. I am a shorter rower so initially my performance at low rating stuff wasn't great due to lack of leverage, I am hoping to make up for this with training in that range, but eventually if I decide to do time trials / races / tests I'll have to start training high rating again. I sort of planned to get to 2:00/500M for 45 mins R20 and then I was going to switch to Pete Plan, hoping that whenever I reach that point, my CNS is more normal and I don't feel as punished as I do now whenever I do high rating sprint pieces.

When I switched to slides from a static C2 Model D, it was pretty hard initially to make wattage at low ratings but I have adapted to it now and it feels pretty decent. My force curve looks much better now than it did a year ago.

[nick rockliff]

Didn't realise that so many people drilled down into the numbers so much

After nearly 20 years using the erg and 10s of millions of metres I can honestly say that I've never had the PM display on anything other than pace. I wouldn't have a clue what the watts are for a given pace and it's not really of interest to me.

We have to dig into the numbers if we are ever to get close to your all time PB's

You don't need to dig into numbers you just need to get your finger out

[faach1]

May someone enlighten me by explaining who Paul Smith is? (The SPI “creator”)

What are/were his edging credentials? Etc..

[robbiep]

I'd like to apologise. I think that, rather than a can, I've opened an entire barrel-load of worms with my original question !

I suppose I can see what people are talking about with SPI, thinking about it it does seem to be an indicator of strength as anything else (a larger frame will be able to pull harder than a smaller frame, for the same stroke rate), and I can also see how it could be a guide to an improvement in technique over time (if you can pull more efficiently, then that would translate to faster pace (and more watts) for a similar stroke rate too.

However, you'd have to untangle that from your training giving improvements, to what extent is one helping rather than the other, etc

Unlike Nick, I do occasionally look at my watts or calories. But I can safely say my PM3 spends 99+% of the time on pace

My workout today, I did 6k in 24:36, at 21spm, drag factor 143. That calculates out at 188W average, which is 8.95 'something' in the SPI.

I could just as easily pulled harder per stroke, dropped the rate down to 18, and ended up with the same time. But it would be a figure of 10.5 or so.

Or I could drop the drag factor down to 120 or so, do light fast strokes, and do the same workout at 24spm, and turn out a figure of 7.8.

I'm not sure any of those 3 figures - 7.8, 8.95, or 10.5, would actually tell me anything worth knowing.

My bigger build and distance swimming (and running) background suits a lower stroke rate - I'm comfortable grinding out pieces at 20-22spm, I can just keep on going at that rate. Even my 2k pieces don't go above 30spm

[Citroen]

May someone enlighten me by explaining who Paul Smith is? (The SPI “creator”)

What are/were his erging credentials? Etc..

Paul invented the C-Breeze. He was also active on here at one time.
memberlist.php?mode=viewprofile&u=21 (he was more active before the Great Forum Disaster of March 2006)

He invented "Paul's Law" (more correctly "Paul's Conjecture"). viewtopic.php?f=3&t=7708

http://www.ps-sport.net/AboutUs.htm

[Yankeerunner]

May someone enlighten me by explaining who Paul Smith is? (The SPI “creator”)

What are/were his edging credentials? Etc..

Paul Smith had been quite a good rower in his day and became an excellent coach. While occasionally sarcastic, depending on who had riled him, he was a great contributor on this forum. It's too bad that he's not here anymore.

One of his techniques that led to all my PBs was to do most training at 10 meters per stroke while rowing strapless, aka S10MPS. It enforced a power discipline at assured that improvements were made in fitness and technique rather than fooling oneself by simply upping the stroke rate to get a fast split. Rowing strapless assured that the recovery wasn't rushed and the ratio of drive to recovery was in the right ballpark. Of course on race day one would strap in and lift the rate, but with power on the drive and recovery ratio hopefully ingrained. Rocket Roy Brook became a world champion and world record holder with Paul as his coach. And so did Dennis Hastings.

Back when WIRC (CRASH-Bs) had morning heats and an afternoon final for the Open championship sometimes the fastest time of the day came in the morning heats by someone who wanted to be absolutely sure of being in the final, only to do poorly in the afternoon because of exhaustion. Paul suggested a special award, a Sledgehammer, for the fastest time to honor such full efforts. Although CRASH-Bs never did that, and eventually went to a one race only format, the Newburyport Erg 2 Kilometer Championships (NE2KC) adopted the idea and named it for Paul......The PaulS Sledgehammer Award. There are 14 of them throughout the country.

His thoughts on SPI were hijacked and used for evil.

I wish Paul Smith was still on the forum offering good advice.

[hjs]

May someone enlighten me by explaining who Paul Smith is? (The SPI “creator”)

What are/were his edging credentials? Etc..

Mostly the guy who invented 10 mps training. Meters per stroke. Only a limited number of people used it.
Most training strapless.
10 mps means no low rate work.
Most sessions 6/8k. Often with speedbumps.

It can get you fit pretty rapidly. Sessions are relative short.

[ampire]

Something probably more accurate to watch is the peak force (and average force) on the ErgData app. I pay attention to my peak force and try to push a similar peak force each stroke, but sadly it doesn't upload those numbers into the logbook. Consequently, it's a little harder to track over time as opposed to dividing two numbers to get the ratio (SPI = watts / stroke per minute).

[flatbread]

I know that very smart engineers developed the C2 erg -- but, my experience with powermeters (I first used SRM in '98, and have used a variety of devices since then) makes me ask "where's the strain gauge?" "how do you calibrate this?" "how do you know it's accurate?"

looking at watts, or watt minutes, is interesting -- but what's the way to check the calibration and accuracy of an individual C2? Or, is it like a turbo trainer for the bike -- it has a predictable power curve, and the PM5 does the calculation based on flywheel speed, but it's just an estimate, not a direct measurement (with a calibrated strain gauge).

(which is a perhaps obtuse way of asking "why not just look at pace?")

[Citroen]

I know that very smart engineers developed the C2 erg -- but, my experience with powermeters (I first used SRM in '98, and have used a variety of devices since then) makes me ask "where's the strain gauge?" "how do you calibrate this?" "how do you know it's accurate?"

It's based on the angular momentum of a rotating body with known mass.
http://eodg.atm.ox.ac.uk/user/dudhia/ro ... meter.html

The flywheel sensor is a simple hall effect rev counter.

[nick rockliff]

"why not just look at pace?"

Why not? Indeed.

[Yankeerunner]

One last (probably) word from me on SPI is that my recollection is that Paul Smith thought it useful in putting together team boats. For instance, way, way back when I was capable of doing sub-7:00 for 2K I wasn't necessarily a good fit in a boat with other sub-7 rowers. In order for me to go that fast I needed to row at 37-38spm for most of the race and kick in the last 500 at an ever increasing rate of up to 48. Most other rowers would accomplish what I did with a much lower stroke rate. Testing me using SPI would probably mean putting me in a different boat than other sub-7 rowers, much to the relief of those who could generate that pace at 30-32spm and would find me to be an anchor at that stroke rate.

[flatbread]

I know that very smart engineers developed the C2 erg -- but, my experience with powermeters (I first used SRM in '98, and have used a variety of devices since then) makes me ask "where's the strain gauge?" "how do you calibrate this?" "how do you know it's accurate?"

It's based on the angular momentum of a rotating body with known mass.
http://eodg.atm.ox.ac.uk/user/dudhia/ro ... meter.html

The flywheel sensor is a simple hall effect rev counter.

what cycling powermeter nerds would call "virtual power." yes, it's a known mass, but how are the manufacturing tolerances? with turbo trainers, the mass and the fluid resistance are known, and it's easy to do the math(s) and plot the curves. then you compare the virtual power to a calibrated powermeter and see that many units from the same manufacturer have variances (as do strain gauge powermeters, but that's another rabbit hole).

(I think)

[jackarabit]

Gather ye picofarads as ye may, W’/stroke WILL drop as ye age out sans eyes, ears, nose, and working limbs.

[jamesg]

know that very smart engineers developed the C2 erg

Thanks to them and the intermittent rowing action, with an air-braked flywheel, PM can calculate how much work we did last stroke. The necessary and sufficient data that reaches the PM is an impulse stream from the flywheel, approximately one impulse every 3 cm of chain travel during the pull.

This system was available only from C2 well before consumer strain gauges. Being inherently digital, the C2 system is not subject to drift due to age, temperature, false zero etc, and needs no calibration.

From work last stroke, PM derives Watts, speed, pace, meters, force, length of stroke, and we can see them any and all of them as we like.

Since training happens only if I do any work, and I am prepared to see how little work I actually do (about 10 kWh this year so far), using Watts I can track cause and effect directly. An hour a day at 200W would be 73 kWh per year.