Drag Factor From A Wheelchair

Talk about the ski ergometer and training tool from Concept2
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wheels19751
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Drag Factor From A Wheelchair

Post by wheels19751 » February 16th, 2022, 12:12 pm

Hi

I own the SkiErg as a wheelchair user and love it. Yesterday I wanted to set my drag factor to around 120 after reading the blog post about the drag factor of Olympians. In that article, it was said that a drag factor of around 120 should equate to a damper setting of 4. In my case, in order to achieve drag factor of 120, my damper setting has to be about 8. I realize that this is most likely due to the fact that I do not harness drive and power through my legs. However, drag factor 120 is relatively low and high damper settings are hard to sustain for long periods.

Any ideas about this? Am I doing something wrong or is this just something I have to accept as a wheelchair user?

Nomath
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Re: Drag Factor From A Wheelchair

Post by Nomath » February 16th, 2022, 3:34 pm

The drag factor is a measure of how fast the flywheel drops in rotation speed when there is no power input. It doesn't matter how strong your pull is. However, the drag factor depends on the air circulation in and out the flywheel cage. If the perforated air outlet is dirty or dusted, the drag factor drops. So you probably have to clean the flywheel cage if a damper setting at 8 results in a drag factor of 120.

It is remotely possible that for a very weak stroke the resistance of the spinning flywheel is not purely from moving air because the resistance of the flywheel bearings is no longer negligible. The calculated drag factor then becomes dependant on the stroke power ; however, the stroke power calculated by the PM5 also goes wrong. I think this is very unlikely to happen.
Last edited by Nomath on February 16th, 2022, 3:36 pm, edited 1 time in total.

Spinal
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Re: Drag Factor From A Wheelchair

Post by Spinal » February 16th, 2022, 3:36 pm

Damper setting of 4 on my 18 month old SkiErg produces a drag of around 80.

I wouldn't fancy more than a short sprint at 120 drag
1981, 174cm, 70.5kg LWT
Row 2k 6:58.2 5k 18:43.8
Ski 5k 18:49.1 60mins 15105mtrs HM 1:23:59.6

winniewinser
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Re: Drag Factor From A Wheelchair

Post by winniewinser » February 17th, 2022, 3:16 am

wheels19751 wrote:
February 16th, 2022, 12:12 pm
Hi

I own the SkiErg as a wheelchair user and love it. Yesterday I wanted to set my drag factor to around 120 after reading the blog post about the drag factor of Olympians. In that article, it was said that a drag factor of around 120 should equate to a damper setting of 4. In my case, in order to achieve drag factor of 120, my damper setting has to be about 8. I realize that this is most likely due to the fact that I do not harness drive and power through my legs. However, drag factor 120 is relatively low and high damper settings are hard to sustain for long periods.

Any ideas about this? Am I doing something wrong or is this just something I have to accept as a wheelchair user?
That reference may have been referring to Rowergs perhaps.....I've heard similar previously.

The Skierg has a slightly different setup where there is a cover on the flywheel so the DF's are lower compared to Rowergs unless you remove that cover.

Personally I find something around 80-85 works for me for 2km upwards. I would push it higher for anything shorter in distance. I would struggle to use DF120 for a 2k.
6'2" 52yo
Alex
Recent 2k - 7:19
All time 2k - 6:50.2 (LW)

Nomath
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Re: Drag Factor From A Wheelchair

Post by Nomath » February 17th, 2022, 7:46 am

winniewinser wrote:
February 17th, 2022, 3:16 am
The Skierg has a slightly different setup where there is a cover on the flywheel so the DF's are lower compared to Rowergs unless you remove that cover.
I didn't know this cover and it probably explains why the drag factor is much lower at a damper setting at 4.
Anyhow, the drag factor has no relation with how you produce a force on the handle -by legs, hips or arms- and with the magnitude of the force.

JaapvanE
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Re: Drag Factor From A Wheelchair

Post by JaapvanE » February 17th, 2022, 9:51 am

But it could be a deliberate modification to adapt the skiErg to a specific group of users, making the damper setting more useable for that group. A dragfactor of 225 of a clean unmodified machine is already considered dangerous for olympic athletes. So modifying the damper provides a much more useable range in the damper settings. In all honesty, I'm wondering why they don't install such modification in gyms by default to prevent injury. On the other hand, neglect in cleaning it typically resolves this as well.

However, novice users might get trained in setting the damper to 8 at home, just to find a well maintained unmodified SkiErg and be taken by surprise.

winniewinser
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Re: Drag Factor From A Wheelchair

Post by winniewinser » February 17th, 2022, 10:31 am

JaapvanE wrote:
February 17th, 2022, 9:51 am
But it could be a deliberate modification to adapt the skiErg to a specific group of users, making the damper setting more useable for that group. A dragfactor of 225 of a clean unmodified machine is already considered dangerous for olympic athletes. So modifying the damper provides a much more useable range in the damper settings. In all honesty, I'm wondering why they don't install such modification in gyms by default to prevent injury. On the other hand, neglect in cleaning it typically resolves this as well.

However, novice users might get trained in setting the damper to 8 at home, just to find a well maintained unmodified SkiErg and be taken by surprise.
Most gym users whack it up to 10 either for their ego or cos they think it will make them go faster :roll: . I've tried telling people before but they don't care.....even the Gym PT's don't know how to set it correctly.
6'2" 52yo
Alex
Recent 2k - 7:19
All time 2k - 6:50.2 (LW)

wheels19751
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Re: Drag Factor From A Wheelchair

Post by wheels19751 » February 17th, 2022, 11:49 am

Hello:

Thank you for all the replies. I now understand a little better. I will definitely clean the flywheel. I also find that I do pretty well for longer sessions at a damper of 5. The ability to modify the Skierg on the fly based on the type of user would be great

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Re: Drag Factor From A Wheelchair

Post by jamesg » February 17th, 2022, 11:57 am

1. In my case, in order to achieve drag factor of 120, my damper setting has to be about 8.
2. I realize that this is most likely due to the fact that I do not harness drive and power through my legs
1. What's so special about 120? If you can't pull hard, use a lower drag to keep the speed up: Power = Force x Speed, so both are needed.
2. Drag is a machine characteristic and does not change with force applied, only with the amount of air that passes through.

I'd try setting drag as low as possible while still keeping the PM operational and your pull fast and at a force level where you want it. Drag is there to suit the machine to us, not us to the machine.
08-1940, 179cm, 83kg.

mict450
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Re: Drag Factor From A Wheelchair

Post by mict450 » February 17th, 2022, 12:14 pm

winniewinser wrote:
February 17th, 2022, 10:31 am

Most gym users whack it up to 10 either for their ego or cos they think it will make them go faster :roll: . I've tried telling people before but they don't care.....even the Gym PT's don't know how to set it correctly.
Truer words were never spoken.
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hjs
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Re: Drag Factor From A Wheelchair

Post by hjs » March 5th, 2022, 7:19 am

wheels19751 wrote:
February 16th, 2022, 12:12 pm
Hi

I own the SkiErg as a wheelchair user and love it. Yesterday I wanted to set my drag factor to around 120 after reading the blog post about the drag factor of Olympians. In that article, it was said that a drag factor of around 120 should equate to a damper setting of 4. In my case, in order to achieve drag factor of 120, my damper setting has to be about 8. I realize that this is most likely due to the fact that I do not harness drive and power through my legs. However, drag factor 120 is relatively low and high damper settings are hard to sustain for long periods.

Any ideas about this? Am I doing something wrong or is this just something I have to accept as a wheelchair user?
In a Skierg c2 does put a ring in the cage to lower the drag. That can be removed if you want to and will give a good bit extra drag.
That said, if you are sitting, and only using your arms/upperbody drag 120 sounds high. I would use a lot lower. The top guys, who pulled sub 6 on the skierg do use 120 ish.

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