Just did an hour row, why is my watts so much lower than my bike?

[jamesg]

Was the OP on a C2 bikerg? If this and the C2 rowerg measure power the same way, it would be interesting to see how the same apparent effort or HR shows on them in Watts.

[Carl Watts]

Was the OP on a C2 bikerg? If this and the C2 rowerg measure power the same way, it would be interesting to see how the same apparent effort or HR shows on them in Watts.

Its irrelevant. If ANY bike is accurately measuring the power and the Erg is accurately measuring the power then the correction factor due to your body not being as efficient at generating power on the Erg compared to a Bike requires a 30% boost. Its that simple.

If you want to use the rower on Zwift with the cyclists, the Rowedbiker app just bumps your power 30% and it also doubles your rower rating and adds 40 so it brings up your numbers to closer match the cadence as well.

All your really interested in is attaining an identical effort as it relates to your heartrate to produce the same power on the rower as the bike.

Generating 200W on the rower will give you the same HR as generating 260W on the bike. There are other variances but clearly this is pretty close for your typical weight road cyclist in the 70Kg area.

[btlifter]

I won't speak to the physics of physiology...


But subjectively - and I know this is true of several who row at a level similar to me - the paths in power only become divergent after somewhere about 5-10 minutes.

For me, 2k and under I'm as fast/faster on the rower for the same effort. As the distance ce increases I become comparatively much more efficient at the bike (e.g my 100k on the bike and half marathon on the rower are about the same pace).

[mjk]

https://pubmed.ncbi.nlm.nih.gov/3193864/

"Results indicated that energy costs for rowing ergometry was significantly higher than cycle ergometry at all comparative power outputs including maximum levels"

Also, here's an old forum thread discussing the same topic: viewtopic.php?f=31&t=186612

[MartinSH4321]

Here's a study comparing rowing and cycling which says working efficiency for rowing is 0.19 and for cycling 0.23

https://link.springer.com/chapter/10.10 ... 0301-0_127

If I read it right the total effort of rowing at 190W and cycling at 230W are the same, or in other words, cycling is about 20% more efficient than rowing.

The study was done with "well-trained rowers" so bad rowing technique shouldn't be a problem.

[Carl Watts]

The variance would be pretty bad at the extremes ends of the scale. If you took an elite cyclist and stuck them on a rower and they had never rowed before it would be ugly. Also based on the fact that the ideal body type for both sports is totally different your going to see a variance there as well.

The 30% would be for your typical person of average weight and height who is "Equally" trained in both disciplines. I guess it just comes down to you personally doing the actual testing yourself but with a little understanding of the difference that exists, it shouldn't then come as a massive surprise and its not your equipment that is necessarily inaccurate at measuring power.

Note that this is also just about raw power, how this translates to actual speed on the bike on the road and the boat OTW are different again, its only about trying to look at a HR comparison between two static bits of exercise equipment that can measure power accurately so its just about trying to match the "Intensity" of the rower to the bike.

Really its only been of interest to me me of late when trying to use the rower in Zwift. You kind of want some sort of correction factor, even if its pretty crude. Its not like I'm somehow going to jump on the rower and go straight into the A cat anyway and for my age and performance it looks like the D cat provides others to ride with at sub 3W/Kg.

[Nomath]

If I read it right the total effort of rowing at 190W and cycling at 230W are the same, or in other words, cycling is about 20% more efficient than rowing. ...

It's not a constant percentage difference. Have a look at the graph on the previous page and you'll see that it is roughly a constant 50W difference at varying power levels.

... If ANY bike is accurately measuring the power and the Erg is accurately measuring the power ....

The RowErg is accurately measuring power input at the flywheel, but it is NOT accurately measuring the power input at the handlebar !
Boyas has shown that there is 20-25W difference between power measured at the handlebar and power measured at the flywheel. They measured power at the handlebar by a combination of a force sensor and a speed sensor (power=force x speed). Read the summary of the linked paper or look at the Figure 1A and 1B on the last page.

[Carl Watts]

The RowErg is accurately measuring power input at the flywheel, but it is NOT accurately measuring the power input at the handlebar !

Yeah but thats like saying the power at the pedals is not the same as the power at the rear wheel .Its not the same but you don't care.

Not interested in the mechanical loses in the machine, your interested in the efficiency of the human body to perform a certain exercise.

As fundamentally the bike and the Erg are pretty much the same with a chain and a few bearings you can pretty much cross the mechanical loss/difference out.

Cycling is "Easier" on the body, the power is applied in a more constant fashion and your not constantly moving the body like you are on the Erg. The two main differences add up to be a significant factor. Even the breathing is horrible on the rower, it reminds me more of swimming where it has to become part of the cycle so it becomes a factor of your rating. The power loss difference would also not be a constant as it changes with rating. The Erg also suffers badly from not being able to select a "Gear" to optimize the power delivery (Your not allowed to change the DF during a row) you could argue its like cycling on the flat with a fixed gear bike so its only "Perfect" over a narrow speed range that you have to get to then maintain for the best performance.

Bottom line is the rowing action is horrible. If it was any good a bike would have 4 wheels and you would be using the rowing action to power it. Yes they have been made but why would you want one when 2 wheels is faster.

The only real reason I use the Erg is because it uses more upper body muscles over the bike so its a better balanced exercise if you had to choose between one or the other. The bike is all legs.

[kini62]

Was the OP on a C2 bikerg? If this and the C2 rowerg measure power the same way, it would be interesting to see how the same apparent effort or HR shows on them in Watts.

Elite Suito and Zwift.

I appreciate the discussion. I'm going to agree with Carl that 24-30% difference is probably the norm for us average athletes.

[Cyclist2]

Bottom line is the rowing action is horrible. If it was any good a bike would have 4 wheels and you would be using the rowing action to power it. Yes they have been made but why would you want one when 2 wheels is faster.

Here is a two wheel rowbike: https://row.bike/ If they weren't so expensive I'd get one. I doubt they would be very efficient going up climbs, but you'd get a heck of a workout!

[frankencrank]

I had a similar issue. In fact, I used to believe that rowers put out more power than cyclists. I no longer believe this. (They have higher VO2max but they are less efficient for several reasons - see below) I was so amazed at how low my rowing wattage was I questioned C2 regarding the accuracy of their power meter. I have studied this and there are several things compounding together to make the difference.

1. Bikes measure power somewhere between the pedal and the road (pedal, crank, spider, chain, rear hub). There are minimal losses between what the rider does and what the power meter sees. On rowing ergometers (at least the C2) power is measured at the fan so the shock cord provides substantial lessening of the power the fan sees and what the handle sees (what the rower actually does). That is one source. That will vary with the stroke rate.
2. There are some physiological disadvantages to the rowing that makes the muscles less effective than they are in cycling. There is less time for blood flow during recovery because the muscles are contracted about half the stroke cycle whereas in cycling the muscle contract about 1/4 of a pedal cycle.
3. The cyclist can incorporate twice as many leg muscles as the rower. While the rower can use his arms, the leg muscles tend to be bigger than the arm muscles.
4. On my C2 when on the flat the slide moves slightly up during the power phase. This requires power to push the weight of the body up that slope that the flywheel never sees. (this is tiny in most but not zero if present).
5. At high stroke rates the kinetic losses accelerating the body back and forth are probably greater than the kinetic losses the cyclist sees making the pedals go around. Both of these losses will vary with the cube of the stroke or pedal rate so the difference could be quite substantial or small depending upon what you do on the bike and rower.
6. The upper body muscles used to generate power in rowing, especially the back and shoulders) are probably not very efficient in doing so even though they are quite large.

So, rowers burn more oxygen than cyclists on a pound for pound basis but generate less power on a pound for pound basis as near as I can tell. This difference is compounded on the rowing ergometer.

I did recently post an analysis of the physiology of rowing in which I bring up some of these differences. viewtopic.php?f=3&t=200997

[frankencrank]

This discrepancy is largely not due to the movement of the rower during the recovery, but probably caused by losses in the drive mechanism of the RowErg.

That discrepancy is almost entirely due to the potential energy being put into the shock cord during the power phase reducing the power seen by the flywheel. If they would have varied the stroke rate in their study they would have seen the discrepancy vary.

I am blown away at the choices C2 made in measuring power. Accurately measuring the power would have been so easy (and it didn't have to be measured at the handle).

Luckily, it is just a number and what most are interested in is whether they are improving or not.

[Ombrax]

That discrepancy is almost entirely due to the potential energy being put into the shock cord during the power phase reducing the power seen by the flywheel.

If the user doesn't get the work done on the bungee during the drive back on the recovery (which obviously would not be measured by the erg, but would still benefit the user) then the only place it can go would be to be converted into waste heat. One of these days I'm going to have to get a pyrometer and get before and after bungee cord temperature measurements. I bet it won't change much, if at all.

[Carl Watts]

The loss into the bungee and bearings is negligible. Also at least 60 to 70% of it is returned to you in the recovery.

kinetic losses moving your whole bodyweight up and down the slide at high ratings is massive.

[Nomath]

This discrepancy is largely not due to the movement of the rower during the recovery, but probably caused by losses in the drive mechanism of the RowErg.

That discrepancy is almost entirely due to the potential energy being put into the shock cord during the power phase reducing the power seen by the flywheel. If they would have varied the stroke rate in their study they would have seen the discrepancy vary.

Read the paper! The investigators increased the power stepwise from quite low to exhaustive. The stroke rate was left free to the subjects. It is very likely that in this incremental test the stroke rate also varied from low to high. The data do not indicate that the discrepancy varies with power.