Sources of resistance not picked up by drag factor

[btb1490]

This goes along with my previous post here:
http://www.c2forum.com/viewtopic.php?f=10&t=12050

I may be just spinning my oars here, but I got a Model E rower for home a few weeks ago, the same exact model that I use at the gym. The splits I can hit at home are consistently never as good as the splits I can hit at the gym, despite the same drag factor settings. Today, I did my first 2k TT on the home rower, and it was 10 seconds slower than my TT attempt just the previous week, which was on the gym rower. I felt strong and put in a good effort, but the final time didn't reflect it.

While mopping up after my row this morning, I nudged the seat so I could wipe the rail off and noticed the seat only moved about 1 inch before stopping. At the gym, the seat easily glides from one end of the rail to the other when you nudge it. At home, when I lifted the back end of my rower, I had to lift it pretty high in order to get the seat to move. So my guess is that this seat friction may play a part in why my rows at home don't match my rows at the gym.

But then I got to thinking "what other factors could add to the rowing resistance that may not be picked up by the drag factor calculation?" Does the shock cord tension add to how hard it is to pull the handle? I know from my cycling days that chain lubrication or tight links can add a lot to the resistance of the pedal stroke, so I suspect the same holds true here. What about the freewheel sprocket? A sticky one of those will slow things down, but I think that is something that the drag factor would pick up.

I probably shouldn't care so much, and just be happy with my workouts, but if there are other factors that can add to the difficulty of your row that the drag factor doesn't take into account, certainly in a competition it would matter, and one rowing machine would have an advantage over another.

[Carl Watts]

I run a Model C that can take two monitors for testing purposes. It is fitted with two tach pickups and when rowing the two monitors are never identical with the readings, when in theory they should be.There may be very slight changes between the differnt monitor revisions

Other things I notice is the Flywheel on the C continues to spin long long after the D when I have stopped rowing. This would just be due to the lower milage on the D and the grease in the bearings is causing more braking. There may be an advantage moving to some high quality, lower friction bearings here but it would be very very small I should imagine.

If you have clean set rollers, good bearings and a clean slide and the floor is level the seat should roll down to the catch position unassisted.

There have been others here who have had a rave about the losses in the bunge cord, but really there are other things that are more important to worry about like the condition of the chain and sprocket and a little lubriaction to the plain bearings inside the frame for the chain rollers..

[johnlvs2run]

the seat only moved about 1 inch before stopping. At the gym, the seat easily glides from one end of the rail to the other when you nudge it. At home, when I lifted the back end of my rower, I had to lift it pretty high in order to get the seat to move. So my guess is that this seat friction may play a part in why my rows at home don't match my rows at the gym.

Definitely. There are 3 sets of holes under the seat, that adjust the seat tightness on the railing. I always put the bolt through the last set of holes, so the seat would glide as easily as possible.

But then I got to thinking "what other factors could add to the rowing resistance that may not be picked up by the drag factor calculation?" Does the shock cord tension add to how hard it is to pull the handle? I know from my cycling days that chain lubrication or tight links can add a lot to the resistance of the pedal stroke, so I suspect the same holds true here. What about the freewheel sprocket? A sticky one of those will slow things down, but I think that is something that the drag factor would pick up.

The drag factor only picks up the resistance of the fan.

I feel tight bungees can definitely make a significant difference in the times. When I changed the bungee in my old modelB, the rowing got more difficult. It became more difficult to hit the same times from previously.

[Citroen]

Definitely. There are 3 sets of holes under the seat, that adjust the seat tightness on the railing. I always put the bolt through the last set of holes, so the seat would glide as easily as possible.

No they don't. The bolts hold the bearings to the frame of the seat, nothing more. New bearings may start out a bit stiff as Carl pointed out above.

The drag factor only picks up the resistance of the fan.

I feel tight bungees can definitely make a significant difference in the times. When I changed the bungee in my old modelB, the rowing got more difficult. It became more difficult to hit the same times from previously.

The drag factor is simply calculated from the tacho signal from the flywheel pickup. The pickup is triggered by the magnets on the flywheel. That's the only connection between flywheel and monitor. The position of the damper lever is NOT sensed by the monitor.

Your times get worse ase you age, that's normal.

[Dickie]

Definitely. There are 3 sets of holes under the seat, that adjust the seat tightness on the railing. I always put the bolt through the last set of holes, so the seat would glide as easily as possible.

No they don't. The bolts hold the bearings to the frame of the seat, nothing more. New bearings may start out a bit stiff as Carl pointed out above.

Yes they do. the bolts also adjust the amount of play between the upper and lower rollers on each side of the rail. if there is not enough space between the upper and lower rollers then they squeeze the rail and do not move easily. This is discussed in the documentation of every new machine where instructions are given to alleviate this problem.

Fred Dickie

[Citroen]

Definitely. There are 3 sets of holes under the seat, that adjust the seat tightness on the railing. I always put the bolt through the last set of holes, so the seat would glide as easily as possible.

No they don't. The bolts hold the bearings to the frame of the seat, nothing more. New bearings may start out a bit stiff as Carl pointed out above.

Yes they do. the bolts also adjust the amount of play between the upper and lower rollers on each side of the rail. if there is not enough space between the upper and lower rollers then they squeeze the rail and do not move easily. This is discussed in the documentation of every new machine where instructions are given to alleviate this problem.

Fred Dickie

But it's unlikely that a factory fresh machine is going to have badly adjusted seat bearings.

[johnlvs2run]

No they don't. The bolts hold the bearings to the frame of the seat, nothing more. New bearings may start out a bit stiff as Carl pointed out above.

Actually it's the rollers being discussed, not the bearings. Thank you, Fred.

The drag factor only picks up the resistance of the fan.

The position of the damper lever is NOT sensed by the monitor.

No one said that it was

Your times get worse ase you age, that's normal.

Not within a 5 minute change of the bungee they don't.

[Dickie]

No they don't. The bolts hold the bearings to the frame of the seat, nothing more. New bearings may start out a bit stiff as Carl pointed out above.

Yes they do. the bolts also adjust the amount of play between the upper and lower rollers on each side of the rail. if there is not enough space between the upper and lower rollers then they squeeze the rail and do not move easily. This is discussed in the documentation of every new machine where instructions are given to alleviate this problem.

Fred Dickie

But it's unlikely that a factory fresh machine is going to have badly adjusted seat bearings.

Unlikely or not, mine needed to be adjusted when I got my model C

Fred

[btb1490]

Good discussion here, thanks.

This is hardly scientific, but one thing I took note of on my home rower was how much effort it took to hold the rowing handle in place after pulling it out about 3 feet. I just held it with my pinky finger on one hand and resisted it from retracting back into the housing. It took a fair amount of effort. Then at the gym today, I did the same thing, and it hardly took any effort to hold the handle in place. So I'm thinking that's probably the main source of the extra resistance I feel on my machine at home as compared to the one at the gym. The seat issue probably adds a little to that as well.

I guess if I ever decide to do a rowing competition, I should bring some sort of a portable device to measure how much force there is to hold the handle in place on each machine, and pick the one with the lowest value!

[Bob S.]

I guess if I ever decide to do a rowing competition, I should bring some sort of a portable device to measure how much force there is to hold the handle in place on each machine, and pick the one with the lowest value!

Lots of luck! I have never been at a competition where there was a choice. The seat assignments were all made well in advance. Also, as they are all brand new machines, it is unlikely that there would be detectable differences in them.

Bob S.

[Citroen]

I guess if I ever decide to do a rowing competition, I should bring some sort of a portable device to measure how much force there is to hold the handle in place on each machine, and pick the one with the lowest value!

Bring a fisherman's balance and a couple of feet of fishing line (so you can make a loop to connect the balance to the handle). The pull on the chain should be about 6 to 8 pounds.

That two pounds of tolerance could be crucial to whether you get 6:29.8 or 6:29.9

[Carl Watts]

I guess if I ever decide to do a rowing competition, I should bring some sort of a portable device to measure how much force there is to hold the handle in place on each machine, and pick the one with the lowest value!

Bring a fisherman's balance and a couple of feet of fishing line (so you can make a loop to connect the balance to the handle). The pull on the chain should be about 6 to 8 pounds.

That two pounds of tolerance could be crucial to whether you get 6:29.8 or 6:29.9

Which is true for those who can see the bigger picture. The losses in the cord are obviously not 100% and are probably more like 20% so 80% of the energy you put into the cord on the drive assists you in the recovery. I'm no expert in biomechanics but its pretty obvious your leg muscles are far more efficient on the drive than the recovery (you can leg press way more than you can leg curl) so any energy in the cord that you put in on the drive is offset by it's assistance in the lesser efficient leg muscels in the recovery. The overall is that the difference in losses in the cord between one new machine and another at a competition are insignificant compared to the hundreds of Watts required to drive the flywheel. It's pretty hard to come up with another sport where the playing field is this even.

[johnlvs2run]

the energy you put into the cord on the drive assists you in the recovery

Well then just lock up the cord at the cage.

This way you won't even have to move, and you'll still go just as fast.