Resistance on new black model D

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Re: Resistance on new black model D

Postby Atorrante » February 28th, 2013, 2:13 pm

It is very suspicious that a relative high number of different users find the new black D harder. When I bought it in november I inmediately find it harder, but thought it needs a break in. After almost half million meters logged in it hasn't softened. Back with my 8 years old D my 30 minutes pieces were in the 1:55 pace range, but after the new black D they dropped to 1:57 :(
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Re: Resistance on new black model D

Postby Atorrante » March 1st, 2013, 3:10 pm

With my old D I didn't use at all the drag factor future and tend to use instead the fan numbers. Today I decided the see at what drag factor I was using the new blackly and it was 125. My best remind of the old D was that I row at 115 drag factor, so lowered the fan number from 4.5 to 4 and the DF set to 117. It softened the machine and I was able to reduce my split in the 6K a little. With these new setting I felt it less harder and be a little more motivated to reach for my old faster times.
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Re: Resistance on new black model D

Postby wilyliam » March 4th, 2013, 5:31 pm

I just got mine - I thought it was kinda hard, but I attributed that to the fact that I had not erged regularly in greater than five years ...

:wink:
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Re: Resistance on new black model D

Postby Atorrante » March 5th, 2013, 1:32 pm

wilyliam wrote:I just got mine - I thought it was kinda hard, but I attributed that to the fact that I had not erged regularly in greater than five years ...

:wink:


Yes, it always happens by default. :lol:
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Re: Resistance on new black model D

Postby rowbike » March 6th, 2013, 11:10 pm

I compared the drag factors on my new black model D and the one year old grey model D at the gym with two damper settings. They are as follows:

Damper / Grey / Black
5 / 126 / 147
10 / 198 / 231

I basically have to adjust about 2.5 damper settings to get the same drag. Granted, the grey is a year old and has some dust in the fan, but not too much since it is cleaned regularly. I read on the C2 website that a brand new model D should have a drag factor of 210-220 at damper setting 10, and my black is 231 after about 300k meters.

http://www.concept2.com/service/monitor ... rag-factor

If the 210-220 range is true, its possible there is something about the black models that makes them harder to row. But the weird thing is that C2 says a new rowers should have a drag factor of 90-100 at damper setting 1, and mine is only 83 (That is when my damper is all the way to the bottom. Is that setting 1 or zero?)
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Re: Resistance on new black model D

Postby Ergmeister » March 7th, 2013, 7:46 am

Similar to cars, identical model Ergs drive a little differently from Erg to Erg, year to year. The only way to really fairly evaluate the black versus gray models would be to compare out of the box new black to out of the box new gray.

The PM drag factors should be a constant and a lot of engineering has gone into them to ensure that. I find that all Ergs vary but the drag factor numbers are true and that's why they have them; so that you can adjust any Erg to your desired level. If you disregard the damper position and numbers, and pull only to a specific drag factor, I think on that basis you'll find the differences virtually indistinguishable. I get comments that most will drop their damper by 50% when they get a rebuilt Erg back due to the increase in drag from the rebuild/restoration process. For sure drag factors at a set damper position will drop steadily over time and that's why C2 encourages checking it regularly if you want to be constant.
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Re: Resistance on new black model D

Postby c2jonw » March 7th, 2013, 4:34 pm

I compared the drag factors on my new black model D and the one year old grey model D at the gym with two damper settings. They are as follows:

Damper / Grey / Black
5 / 126 / 147
10 / 198 / 231

I basically have to adjust about 2.5 damper settings to get the same drag. Granted, the grey is a year old and has some dust in the fan, but not too much since it is cleaned regularly. I read on the C2 website that a brand new model D should have a drag factor of 210-220 at damper setting 10, and my black is 231 after about 300k meters.

http://www.concept2.com/service/monitor ... rag-factor

If the 210-220 range is true, its possible there is something about the black models that makes them harder to row. But the weird thing is that C2 says a new rowers should have a drag factor of 90-100 at damper setting 1, and mine is only 83 (That is when my damper is all the way to the bottom. Is that setting 1 or zero?)


Drag factor is a numerical representation of the rate of deceleration of the flywheel, ie, how quickly the flywheel is slowing down. A bigger drag factor number indicates a faster rate of deceleration, and a higher energy requirement to accelerate the flywheel from one given rpm up to another. Air coming in contact with the fan blades is the source of resistance- let more air in (higher damper setting) and the drag factor increases. Close the damper down (or block the air flow with rabbit hair) and the drag factor drops. At a given damper setting on a given machine, the drag factor will increase as the temperature drops (cold air is denser than warm air). DF will decrease as elevation increases and as barometric pressure decreases (less dense air). Air which already has some velocity imparted to it before it enters the flywheel cover will also effect the DF.

From a manufacturing viewpoint, The perforated metal that surrounds the flywheel cover has a tolerance range for the hole size, and this will have an effect on drag factor range. Given all those possible variables, I think the numbers you're reporting are all withing range.

Personally, whenerver I'm setting up an erg I go to the DF screen on the monitor and set the damper for my preferred DF (115-120) and don't pay much attention to the damper number.....C2JonW
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Re: Resistance on new black model D

Postby rowbike » March 7th, 2013, 5:33 pm

I've never relied on the dapmper number. I always set the damper by the drag factor on the screen to be about 135, and it always varies by unit.

I had assumed that as a unit got more dust in the fan the drag factors decreased throughout the range. My black seems to have a wider range than C2 is indicating new unit should have, though I'm sure their numbers are just a general average. I've got no problem having a wider range of drag factors and adjustment.

Despite aligning drag factors, my black model D still feels harder to row than the other grey model D's I use at the gym. This may be due to a newer bunge cord as mentioned earlier.
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Re: Resistance on new black model D

Postby Atorrante » March 8th, 2013, 11:26 pm

My new blackly also feel harder than my old grey. So despite of the clear explanation Jon did about the importance of the drag factor and its relevance to the actual feel and performance each one will have on the erg, my feeling is not anecdotal and I ultimately has accepted I'm not as fast as 4 months ago, but I'm FIT. B)
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Re: Resistance on new black model D

Postby btb1490 » March 19th, 2013, 4:17 pm

I started a post just like this when I first got my Model E for home. I said it felt like it was a lot harder to row than the well used Model E at the gym, given the same drag factor. Everyone said it was all in my head. So where were you guys back then who are now saying the same thing that I said? I could have saved thousands of dollars in psychiatrist visits! :lol:
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Re: Resistance on new black model D

Postby Carl Watts » March 20th, 2013, 3:38 am

I think the only main difference can be the bungee cord tension on a new machine.

What I will say however is that it pays to lubricate the two chain guide rollers inside the frame with a good quality synthetic lubricant as they are assembled dry.

My Model C recently developed a bad squeak / squeal on the drive and it was the rollers. I used a small syringe with a long tip to apply oil right into the bearing. These rollers have been known to seize totally at gyms and then the chain litterally cuts right through it to the bolt !

If you analyse what your trying to overcome in the drive besides the fan resistance, then its not alot. The one way locks onto the shaft so all the bearings in the flywheel are stationary so you have a couple of bearings each side of the sprocket shaft and a few bearings moving on the bungee rollers and chain guide rollers and losses in the chain. Even if the one way bearing is not as free on my Model D as it is on my Model C it makes no differerce as it is absorbed into the flywheel drag factor calculation. The flywheel on the C spins for ages after the same pace at the finish on the same drag when compared to my Model D but I do expect this to improve with time.
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Re: Resistance on new black model D

Postby RBFC » March 21st, 2013, 12:02 am

A couple factors that haven't been mentioned:

1. Is the chain and lubricant the same on the new machines as it has been on the older models?

2. Are the seat rollers and their contact patch area the same on new and old models? Are the same bearings used?

Understand that while these factors may/may not be involved, it pays to look at all moving parts of the system.

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