Removal of the flywheel balance weights

[Carl Watts]

Ok First up a big disclaimer, Concept 2 is NOT going to recommend you do this.

The following works and is better than the standard setup but you need an engineering background and the necessary screws and drills, taps etc.

Basically a 5mm button head cap screw has the same mass in the head of it as the typical flywheel weight balance clips that weigh 1.5 gram.

By drilling 4.2mm holes as close as possible to the root of the blade the clip is attached to and tapping them M5 you can put a screw through from the OUTSIDE of the flywheel into the 1/8" steel of the flywheel and pre cut and file the screws so they are flush on the inside when fully tightened. I used security Torx screws making them difficult to accidentally remove.

I removed all four of the inner clips, note that the clips can be thicker or thinner and Concept 2 has at least two weights, 1.5 gram and 2 gram. If you have a 2 gram clip just insert a thin steel washer under the head of the screw.

The issue we have in New Zealand is massive humidity and the clips will eventually rust away and or just fall off. If you didn't mark the position of the clips BEFORE they fall off your really stuffed, perhaps you can relocate the position of them by looking for a rust mark on the correct blade.

I did NOT remove the single clip on the outside of the blades, this could probably be done with just a grub screw into the plastic but the weight calculation is a little harder as your not replacing steel with steel your replacing steel with nylon plastic.

Note: You would think that such tiny balance weights would have little effect, don't be fooled they have a BIG effect and the balance needs to be near perfect. If its wrong and you have the standard play the bearing housings the flywheel emits a terrible sound on the recovery stroke as the whole flywheel try to bounce around in the housing and you get noticeable vibration in the rower.

Personally I would recommend that Concept 2 use the same technique to balance the flywheel as the car makers in the USA use to dynamically balance the flywheels on the engines.By having pre drilled and tapped holes round the flywheel you simply add the likes of loctite grub screws where required instead of clips. The Japanese precision balance Turbo compressor and turbine wheels that do up to 120,000 rpm by precision milling out a recess thereby simply removing a tiny mass instead of adding it to the opposite side. The other alternative is to at least make the existing clips from stainless steel.

Like I said I take no responsibility in anyone doing this to their rower so don't flame me. The best advice is if its not broke, don't try and fix it. My problem is that I like to make improvements and also modify just about everything I get my hands on.

[c2jonw]

You're right Carl- we do not recommend this. It should be noted that any drilling or filing done on the plastic fan will effect the overall integrity of it, and at high speeds the centrifugal force can cause the fan to come apart rather dramatically.........C2JonW

[Cyclist2]

If you didn't mark the position of the clips BEFORE they fall off your really stuffed

This seems to be the key, whether you use clips or screws. I think it's time to clean my fan housing AND mark the location of the clips!

[jackarabit]

Good point, Mark. The useful takeaway from Carl's experience is of the pound of prevention sort. If you think of a stress riser as missing an appointment or getting a notice of debt collection, best not indulge the latent boy machinist that lurks within! Get your spares from C2.

[Carl Watts]

You're right Carl- we do not recommend this. It should be noted that any drilling or filing done on the plastic fan will effect the overall integrity of it, and at high speeds the centrifugal force can cause the fan to come apart rather dramatically.........C2JonW

Yes which is also another reason why I did not touch the plastic fan. The Concept 2 fan is not rocket science, try rebuilding and modifying a turbocharger into a hybrid that doesn't go bang if you really want a challenge.

The steel part of the fan already has holes in it all over the place, some are pretty big and having had experience with others things with holes in that are moving rapidly, contribute to additional noise being generated.

Other things I noticed is the drag factor increased about 6 points with the weights gone, but then again the fan blades were cleaned also.

Like I said, I don't recommend everyone trying to do this.

The best idea for the masses is to stick a small white label or just use a permanent marker pen and write directly on the steel where the each of the weights are and write letters or numbers on them and a corresponding number or letter on the weight itself.This takes a couple of minutes when your next cleaning your Erg and it is piece of mind knowing you will not be stumped should a weigh ever come off.

[Anth_F]

Wouldn't have thought they could fall off all that easily tbh. Cleaned my fan a few times since owning the machine and them weights seem clipped on pretty solid to me.

Just don't be too heavy handed or clumsy around em when cleaning the fan and i could never see an issue arising.

[Carl Watts]

Wouldn't have thought they could fall off all that easily tbh. Cleaned my fan a few times since owning the machine and them weights seem clipped on pretty solid to me.

Just don't be too heavy handed or clumsy around em when cleaning the fan and i could never see an issue arising.

It depends on a a number of factors, including the number of weights on the flywheel. Some I have seen have a huge number of weights so the chances of one coming off increase. Mine had a total of 5 weights out of the factory.

Really did this as an improvement and it also reduces the risk of the weights coming off to zero and makes the flywheel easier to clean and is better all round if you want to make yourself a "Race Rig".

Also if you take a look at it from an engineering perspective, the factory set-up is not ideal, its a simple as that and there are much better ways to balance it.

If your in the USA a whole new flywheel may be a cheap option, but in other countries like mine you find a new flywheel here costs NZ$350.

[jackarabit]

In fairness to Carl, however little reason there is to believe yours won't throw a weight, the next time you do maintenance, there's even less reason not to trace around each and give it a number repeated on the vane. Cheap insurance.

[Carl Watts]

In fairness to Carl, however little reason there is to believe yours won't throw a weight, the next time you do maintenance, there's even less reason not to trace around each and give it a number repeated on the vane. Cheap insurance.

Exactly, look its up to you, take the advice or just ignore it but personally I have always found the old saying "A stitch in time saves nine", its just cheap insurance the next time you have the flywheel cover off just mark them.

The problem is most people will Google this post AFTER the fact when they find a weight floating about in the bottom of the cage or complain of vibration on the recovery stroke.

[Steve1960VA]

In fairness to Carl, however little reason there is to believe yours won't throw a weight, the next time you do maintenance, there's even less reason not to trace around each and give it a number repeated on the vane. Cheap insurance.

Yeah, sounds like a good idea to me. Simple enough and the price is right.

Might never make use of it, but if needed it would come in really handy.

Never had the cover off mine, but I might do it soon just to take a look-see and to mark these as discussed above.

[Carl Watts]

Never had the cover off mine, but I might do it soon just to take a look-see and to mark these as discussed above.

The Model D is incredibly easy to work on in terms of taking the flywheel cover off.

Just slacken the single outer mesh grille screw a few turns and remove the 4 flywheel cover screws being sure not to loose the nuts if they come out of the recesses for them in the plasic.

The Model C cover is hard work by comparison, trying to get the screws to line up again on reassembly.

Pays to take it apart once a year if your doing say 2 million meters or so.

[Cyclist2]

Just slacken the single outer mesh grille screw a few turns and remove the 4 flywheel cover screws being sure not to loose the nuts if they come out of the recesses for them in the plasic.

Never worked on a D, but potentially losing nuts sounds like harder work than aligning screws. I did the cleaning/weight marking on my C yesterday, took me less than 5 minutes. Just takes a little eyeball to line up the cover so the screws go right back in. One little adjustment bump with my palm and it was lined up. Easy.

In general, Carl, when I see all the work you do on your (or others?) ergs, I wonder just how much is necessary and how much is just you liking to play with it. I have a model B that is 30 years old - I've never had to replace anything except the shock cord. My model C has about 8m meters, and I only oil the chain and clean the dust about twice a year. I don't see any such intensive maintenance or repairs in C2 literature, and unless the machine is abused (like some gym ergs), I doubt such things are required. I'm an engineer and love building, fixing, and upgrading things, but I've never felt the need to mess with my ergs. (I don't sweat as much as you evidently, that is an issue I don't have to deal with).

Anyway, I find your posts very interesting, but can't see myself doing any of those things, other than the simple ones like marking the weights. You obviously enjoy it though, so good on ya!

[Carl Watts]

Overall the Model D has been pretty good, there are a number of improvements you can make to it but just a little regular maintenance is required if you want it to stay up to "Race Specification".

I have worked on a few rowers that are in a serious mess, I couldn't use them to row on at all, basically it needs to stay like its just come out of the box, i.e. like brand new. Even a bit of crud on the slide causing the seat to go over "Bumps" is as annoying as hell.

My Model C has actually been fantastic and pretty much have kept the slide clean and only replaced the shock cord quite recently. The problems with the D have mainly been related to just the ridiculous amount of sweat generated when rowing through summer to try and keep the meters up last season instead of taking like 6 weeks off through the hottest period of the year here in February. Really it was like pouring a bucket of salt water over it on a daily basis and it killed it.

I'm sure your aware like anything mechanical it requires a bit of maintenance for it to stay in top shape.

[Anth_F]

I have a model B that is 30 years old - I've never had to replace anything except the shock cord. My model C has about 8m meters, and I only oil the chain and clean the dust about twice a year. I don't see any such intensive maintenance or repairs in C2 literature, and unless the machine is abused (like some gym ergs), I doubt such things are required. I'm an engineer and love building, fixing, and upgrading things, but I've never felt the need to mess with my ergs.

I believe that to be the case for the majority of C2's. Shock cord replacement in the later years is about the only thing required. The erg is an effective training tool that only needs simple maintenance occasionally to keep it running like a dream.

I would never mess about with things that don't need messing about with (if it ain't broke don't fix it)