A possible DIY solution for hanging gymnastics rings from a too-low ceiling

mydavesat

New member
Here is an idea I had the other day that I would love to run by this community. It should allow people to add an extra meter or so to the suspension of their gymnastic rings without needing a taller ceiling -- a "virtual meter" if you will... It is a DIY solution that should be relatively easy to implement for your average handyman. I am looking for comments and feedback.

The official height for the suspension of gymnastic rings is three meters (about ten feet), but in practice virtually no private person will have a high-enough ceiling. Even in many climbing halls the anchor points in the training area are lower, despite often being located in old industrial buildings.

This can be somewhat of a problem. The rings move on the surface of a sphere with a radius equal to the strap length. The longer the straps, the less stable the rings and the more difficult the exercises. Hence the need for gymnasts to standardize the length of the straps.

The idea is to add a virtual length H to the straps by suspending the rings from a cable of length L that itself is anchored to the ceiling with two anchors a distance w apart. If the strap glides over the cable relatively frictionlessly, by means of grease or lubricants for example, it will be as if the rings are suspended from a virtual anchor a distance H above the ceiling. This figure should make clear what I mean.

However, the point connecting the strap to the cable describes an ellipse instead of the circle we need. Luckily, cable length L and anchor distance w can be geared to one another such that the ellipse well resembles the circle with the needed radius (technically, both will have equal curvature for small deviations from equilibrium). The cable length L that does the trick is given by L = w sqrt( 1 + 0.25 w[sup]2[/sup] / H[sup]2[/sup] ). In the figure a good approximation to this formula is given for those that don't have access to a scientific calculator with a square root.

Let's fill in some numbers. If we want to add an extra meter, then H = 100 cm, and if we also choose the anchor points w = 100 cm apart, then the cable length L needs to be 112 cm. For our American friends: set w to 40 inch and L to 45 inch to gain an extra H = 40 inch in height.

A few remarks:
  • The sagging of the cable has been accounted for completely, the virtual anchor is a distance H above the ceiling, not above the lowest point of the cable.
  • Has anyone heard about a similar system before? How realistic/practical do you think it is?
  • This will only move the suspension upward for one direction of movement. If you're interested in improving your iron cross, for example, the cables should be installed laterally with respect to your body.
A final remark on safety. For the strap to glide well over the cable, we want a relatively large opening angle. However, this multiplies the forces on the anchors. The opening angle A and multiplication factor M can be calculated with A = 180° - 2 acos( w / L ), and M = 0.5 / sqrt( 1 - w[sup]2[/sup] / L[sup]2[/sup] ). For the numbers above, this yields A = 126° and M = 1.11 Meaning that in this case the load on each anchor is only 11% more than normal, and since this is well within the natural weight variation of users, anchors of about the same quality as usual must be used. Finally, never ever loop the cable through anchor 1, to anchor 2 and then back to anchor 1; as this almost doubles the load on the anchors, it is affectionately called the "American death triangle" in the climbing community.

Edit: Lots of feedback. The structural engineers seem to be worried about bending and shear forces on the anchors. So proceed with care. Many practitioners seem to think adding the extra meter is not worth the hassle as the difference in stability isn't all that big.
 
@mydavesat Oh man it has been a while since I've thought about this stuff, but I would be concerned about the type of load on the anchor instead of just the change in magnitude. An anchor that was previously mostly in tension now has shear and bending force on it.
 
@mydavesat I'm a structural engineer who has worked both with and suspended from IRATA approved ropes access anchor systems. I would highly recommend against installing anchors that will see dynamic loading in a residential ceiling without seeking advice from an appropriate engineer in your area.

Dynamic effects may induce extremely high loads into your system - often many multiples of a person's own bodyweight (say 5x-6x). Please don't pull your ceiling down on you. This will ruin your day.

Nevertheless, if you have received expert advice that this loading is able to be borne by your house ceiling structure, you could research IRATA approved ropes anchors from suppliers. These are designed to work in shear and bending. I'm sure there are other alternatives too.
 
@kenthi Thanks a lot. Would this system differ substantially from a normal implementation for rings? I mean if you were to just bolt the anchors into the ceiling, ie without all this cable stuff i ve proposed here, would there be the same type of problems or would you be better off?
 
@mydavesat It depends really. The dynamic stuff never goes away as that has more to do with your movements than what you're holding on to. Generally, the way to reduce dynamic loads without getting rid of the user is to add some springiness into the support system, but this can become complex quickly.

The other factor is that you have two anchors per ring with your cable arrangement, rather than just one with a traditional fixing (I think?). However, like you said, this is a mixed blessing as this can actually amplify the forces in the system depending on the rigging arrangement (angle A and whether the cable is loaded symmetrically or off to one side).

Sorry, I'm not sure that's super helpful but I'm not able to give you specific design advice.
 
@kenthi I appreciate your comment. Could you please differentiate said situation from one where someone is jumping on the top of the same structure, as often happens? It would seem that similar or worse large dynamic loads are seen by the same structure in the latter situation.
 
@kenthi
I would highly recommend against installing anchors that will see dynamic loading in a residential ceiling without seeking advice from an appropriate engineer in your area.

That applies to every kind of Rings i guess? Not just self made setups.
 
@kenthi To add to the above as well; when the ‘Y’ angle between the dashed lines on your diagram exceeds 120degrees you will start to apply more loads to the anchors and cables than you actually weigh. You will also apply a greater horizontal load to the structure than vertical potentially loading the joists through their weak axis, or causing torsion and twist. Coupled with the dynamic effects described above you may be asking a lot of the structure above and fixings
 
@rejoiceinreality If I’m understanding the graphic correctly, this is reminiscent of the aptly named “american death triangle” style of anchor that rock climbers are warned not to use when building anchors for the exact reasons you’re describing. You can easily end up with several multiples of the weight of the climber on the anchor points depending on the geometry. I can only imagine that similar issues would be at play in this use case.
 
@mydavesat Hah you’re right...that’ll teach me not to read the post in its entirety...that said, it seems like you’d still be multiplying forces by well over 11% given the angles that appear to be far in excess of 45 degrees. I’ll defer to your math though
 
@wc0476 The magnitude of the forces isn't really the problem. They get multiplied by 1, ie stay the same, for 120 degrees. Here it's just 126 degrees and a magnitude just 11 pct more. Some commentators were more worried about bending and shear on the anchors as that is absent in a normal suspension.
 
@mydavesat A few observations:

The official height for the suspension of gymnastic rings is three meters (about ten feet),

This is the official FIG rings frame standard specifications. This means 3m/9.85ft from the ring attachment point to the bottom of the rings. Then they will be another 2.8m/9.2ft over the mat.

I don't know what you mean by 3m in this context, did you mean just the strap length? In summary, you would want the attachment points of the rings to be 50cm/19.7cm wide (W) but changing this does change how it feels on the rings for different elements. Some people prefer them a little wider if they have broad shoulders and their straps are not long enough to not cause interference with the rings touching the body.

I'm about 5' 8"/171cm tall and for me to have a setup tall enough so I can do a hang with toes pointed and not touch the ground and be able to hang inverted without touching the ceiling I would need nearly about 10.5ft or greater but them my strap length would be only 1m. I'd prefer to have them longer, naturally, so 2m would be better than 1m so that makes the preferred setup about 4.1m/13.5ft.

The longer the straps, the less stable the rings and the more difficult the exercises. Hence the need for gymnasts to standardize the length of the straps.

Is it correct that longer straps make elements more difficult? I don't have a problem with straps being too long since my gym setup allows for shorter than desired straps. When I travel and I hang my straps in a new location sometimes the ring straps are much shorter and this makes elements much harder in my opinion, for what it's worth.

Maybe you should try your theory and then let the community know how it works and your own observations for Inverted, and elements above the rings,
 
@bibbigo I meant a 3 m strap length indeed.

I'd love to build this setup myself but right now it's not possible for me. So I thought I'd at least share my thoughts so far.

I'm a bit surprised by your experience of shorter straps being harder. I am under the impression they're easier.
 
@mydavesat Have you worked with elements that use RTO, or transitions where the rings are moving around, e.g. iron cross progressions... ?

Shorter straps vs. longer straps will feel different just like cables with swivels vs. typical 1.5in wife straps feel different.
 
@mydavesat There is a reason gymnastic rings hang from a metal frame mounted to the floor with cables anchored to the floor rather than hanging from the ceiling of the gymnasium. And that is because no ceiling was ever constructed to support weight like that. You’re asking for disaster.
 
@tinekarobinson This is a question worth asking ... but there is hope.

Ceiling joists are often designed for high snow and wind loads (if under a roof) and floor loads (if under another floor). I hang my rings from the floor supports for the floor above and spread the load over two by running a plank perpendicular to the supports.
 
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