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Shock Cord Adjustment

Posted: August 9th, 2010, 1:28 pm
by Montanaandy
I believe that my wife and I have finally reached the point after many millions of meters rowed where I need to tighten my shock cord through an adjustment. The handle while not completely slack, does not seem to provide the same "resistance" that it used to and has a bit too much slack for my liking. I plan on replacing the shock cord as well as the rollers at some point in the not too distant future but want to address the shock cord issue ASAP.

My question is this - how much of the existing shock cord should I pull through the "hook" mechanism in order to get the shock cord tight? The C2 Shock Cord Adjustment PDF is confusing in that the photos initially show about 2-3" of shock cord being pulled through but then the last photo (#8) shows about 1" of cord remaining. Is this because you cut off the other 2" so that only 1" remains. There is no indication that you are supposed to cut the shock cord but I don't see how you get from step 5 to step 8 without doing so. Any assistance would be appreciated. Thanks, Montanaandy

Re: Shock Cord Adjustment

Posted: August 9th, 2010, 4:50 pm
by Citroen
The shock cords should pull the handle back to the front with a force of around 6-8lbs (2.7 to 3.6 newtons). So you can measure that with a fishing scale (or other spring balance). There's no hard and fast rule for length of the cords as they a) stretch with use and b) may be differing lengths due to manufacturing tolerances.

Re: Shock Cord Adjustment

Posted: August 9th, 2010, 7:46 pm
by Atorrante
Mine has about 4 years and more than 3 million meters rowed, and the shock cord pull the handle with enough force to keep it from falling. I think it doesn't need adjustments for now.

Re: Shock Cord Adjustment

Posted: August 10th, 2010, 2:13 am
by Carl Watts
The shock cord only needs enough pull on it to retract the chain. The condition of the chain and bearings will have an influence on this. Mine is definatley not as strong in the retract area as it was but it is now 10 years old, however the chain, sprocket and bearings are all up to race standard so the return friction is minimal.

Ideally you do not want any more tension on the cord than neccessary as your just wasting energy every stroke to overcome it.

The handle should retract all the way to the chain guides by itself or you need to do something about the shock cord. A recent tip that someone gave me is NOT to leave the handle in the holder when your not using the Erg but to let the handle go to the guides. This is better for the cord long term.

Re: Shock Cord Adjustment

Posted: August 10th, 2010, 12:43 pm
by Montanaandy
Thanks for all of the input. I think that I will take a "wait and see" approach at this point based on what I am reading here before I open the machine up and mess with the shock cord.

The handle still retracts back to the front but it tends to slide down towards the bottom of the front area when it is not being used to row, whereas before it would stay in the middle and seemed to be a bit tighter. It is not drooping outside of the area or anything like that.

I really have no way of measuring the lbs of force that are being applied because I don't have the tools which are needed.

Curiously, I was wondering if I was perhaps "cheating" by not having the cord tight(er) and therefore not having as much tension on it as I possibly could on each stroke. Carl's statement that "deally you do not want any more tension on the cord than neccessary as your just wasting energy every stroke to overcome it" put this in a different light and makes sense. I do keep the chain lubricated and clean and keep the rollers and rail clean too. I have never done anything to the bearings or sproket. The machine (C) is around 9-10 years old.

Fortunately, I learned from the start that you only want to keep the handle in the holder when setting the PM for the piece that you are going to row because this will help preserve the tension in the shock cord when it is not in use. Unfortunately, just about every club/place where I use an Erg when traveling does not understand this and I always find the handle pulled into the holder by the previous user and left that way. Montanaandy

Re: Shock Cord Adjustment

Posted: August 10th, 2010, 6:57 pm
by Byron Drachman
Montanaandy wrote: I really have no way of measuring the lbs of force that are being applied because I don't have the tools which are needed.
Montanaandy
You can tie a piece of string to the handle with the other end of the string tied to a bag. Loop the string over a rolling pin held in place. Keep adding stuff to the bag such as cans of food until the handle moves. Now weigh yourself on a bathroom scale with and without holding the bag and take the difference.

http://s149.photobucket.com/albums/s59/ ... handle.jpg

Cheers.

Re: Shock Cord Adjustment

Posted: August 10th, 2010, 10:02 pm
by Bob S.
Byron Drachman wrote:
Montanaandy wrote: I really have no way of measuring the lbs of force that are being applied because I don't have the tools which are needed.
Montanaandy
You can tie a piece of string to the handle with the other end of the string tied to a bag. Loop the string over a rolling pin held in place. Keep adding stuff to the bag such as cans of food until the handle moves. Now weigh yourself on a bathroom scale with and without holding the bag and take the difference.

http://s149.photobucket.com/albums/s59/ ... handle.jpg

Cheers.
Hey Byron, neat! My own thought was that there were no tools required, but I did think in terms of a pulley and known weights. You really got it down to what could be done with the stuff just lying around in almost any household.

Bob S.

Re: Shock Cord Adjustment

Posted: August 11th, 2010, 4:33 am
by Citroen
Bob S. wrote:
Byron Drachman wrote:
Montanaandy wrote: I really have no way of measuring the lbs of force that are being applied because I don't have the tools which are needed.
Montanaandy
You can tie a piece of string to the handle with the other end of the string tied to a bag. Loop the string over a rolling pin held in place. Keep adding stuff to the bag such as cans of food until the handle moves. Now weigh yourself on a bathroom scale with and without holding the bag and take the difference.

http://s149.photobucket.com/albums/s59/ ... handle.jpg

Cheers.
Hey Byron, neat! My own thought was that there were no tools required, but I did think in terms of a pulley and known weights. You really got it down to what could be done with the stuff just lying around in almost any household.

Bob S.
Since the weight is approximately six to eight pounds you wouldn't need to use scales. Pick grocery items in tins with the content weight on the outside. When the sum of the contents is six pounds the collection including the tins will weigh seven pounds - roughly six standard tins of Heinz/Bush's baked beans will do the job (plus will provide a good hearty meal).

A 400g tin of Heinz spaghetti in tomato sauce (we're out of beans - I ate the last half of the last can on toast last night) weighs 460g (1lb == 454g) un-opened.

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