Asymmetry in Cycling

One of our most frequently asked questions is about asymmetry, so we thought we’ll cover the key parts in this post (p.s.: everyone has some degree of asymmetry).

Imprint asymmetry

The imprints we’ve seen usually include two types of asymmetry: sideways twist, and left/right depth difference.

Picture A shows a cyclist’s imprint captured when they sat on the foam while facing forward. If we draw a line through the sitbone impressions, we expect it to be parallel to the foam’s front edge (white dotted line). In this particular case however, we see that the corresponding (blue dotted) line is at an angle, indicating the cyclist’s torso was turned slightly to the left even though they’re facing forward.

The second kind of asymmetry we’ve observed is almost always present. An example is given in picture B, which shows the cross-section of an imprint as seen from the front. Here, the left depression appears to be deeper than the right, even though the cyclist doesn’t think they’re tilting to the left when sitting upright.

Asymmetry categories

The asymmetries observed earlier are the symptoms, which may be the same even though the root causes are different. Depending on the cause(s), the solutions and the need for any may differ. There are two primary categories of root causes: natural bias (or muscle-related) and skeletal.

Natural bias

Natural bias is a result of the way we use our muscles. In the second case above where the left depression is deeper, the cyclist has a history of carrying heavy loads using their right arm. This causes them to tilt slightly to the left even when they’re upright.

Most people have some degree of natural bias, which we’ve learned should not be reflected in our saddle models. Based on our conversations with health professionals and our testing, we concluded that we should not be using the imprint as it is. To eliminate the effect of natural bias present in almost all our imprints, we symmetrize our saddle models by mirroring either the left or right side onto the other.

Put in a different way, we believe that any saddle that adapts to the cyclist should not do so based solely on the pressure exerted on it, and that natural bias must also be taken into account.

Skeletal

The second category is skeletal in nature, and includes leg length difference, scoliosis (sideways curvature of the spine), and hip asymmetry. It is our understanding that leg length difference is the most common, followed by scoliosis, and finally, hip asymmetry is relatively rare.

While symptoms of skeletal asymmetry manifest at the saddle, potential solutions if any differ based on the root cause. For leg length difference, a shim on the shorter leg is the usual approach. Picture C (a) shows the key body and bike parts when everything is symmetrical. Picture C (b) shows a hip that is higher on one side: an asymmetrical saddle is a suitable solution. Picture C (c) shows the result of using an asymmetric saddle when the hips are not: an inappropriate twisting of the upper body/spine.

To determine the root cause(s), we strongly recommend consulting with an appropriately trained medical professional, such as a medical doctor or physical therapist (but not a bike fitter).

How Meld can help

Once asymmetric hips are determined to be the root cause, we recommend the following quick test: Place a folded towel on one side of your saddle and take a short ride. The key is the ‘untwisting’ of the upper body. If the simple test shows some benefit, we will send you three pieces of padding with different thickness. These can be combined and stacked on your current saddle, and you can determine which combination works well for you.

To confirm that the solution works and has no long term repercussions, we strongly suggest working with a physical therapist (not a bike fitter) during this process. Once you and your physical therapist are sure an asymmetric saddle is the right solution, we will then build your Meld saddle with the same additional combination of padding.

Recommended steps

We end our short discussion on asymmetry with our recommended steps from a cyclist’s perspective:

Do you encounter any asymmetry-related issues while cycling?

+ No — you’re probably ok.

+ Yes — you should consult with an appropriately trained medical professional, such as a medical doctor or physical therapist (but not a bike fitter), to determine the root cause(s).

If root cause of asymmetry is determined to be skeletal and hip-related:

+ Perform a simple test: place a folded towel on your current saddle, take a short ride, check that upper body untwists.

+ If simple test indicates improvement: you can contact us to get a padding set, then stack and test which combination works best. Verify with physical therapist (but not bike fitter) that solution works without long term repercussions.

Found this article useful? Check out other cycling-related stuff at meld3d.com/blog.