Nerding Out: Do Kinetic Graphs Really Describe Suspension Performance?

I recently noticed this interesting comment in Alicia Leggett’s recent Revel Rail review.

Techniques developed to measure how active the suspension is on a bike – anti-squat and anti-rise – seem somewhat unremarkable when it comes to this design. If they don’t tell the whole story, what measurements do we have? How do two bikes with the same lever curve have different suspension forces, all other things being equal?

The rail’s anti-squat curves and leverage don’t look all that different on many other modern bikes, so does that mean the suspension won’t work any different?

This topic is something I’ve been thinking about a lot since I reviewed the Marin Wolf Ridge 9 in 2018. This bike is one of three bikes I’ve tested since then using Naild’s R3act suspension, which features a sliding suspension component in combination with the links. Marketing claims indicate that it works in a fundamentally different way from other designs, which allows it to have the best characteristics of other systems without any downsides. Information on how to do this was lacking (and I asked a lot), but I was told not to worry about the kinetic graphs because the Naild system works differently than other bikes, so its true brilliance cannot be explained using the usual methods.

By the way, if you’re wondering what terms like “anti-squat” and “leverage curve” mean, I recommend Dan Roberts’ articles on the topic here and here.

In fact, the Naild system operates at the same level of physical limitations as any other suspension system. It’s basically a four-bar suspension layout, except it uses a slider instead of one of the link axles, so the usual tools (squat resistance, rise resistance, leverage ratio, etc…) explain how it works as well as any other bike . As you can see in this article, they are tuned towards higher resistance to squats and higher pedaling compared to most other bikes, which is not a bad thing because they made them pedal very Efficiently despite the light shock, but there were drawbacks to it.

Therefore, I would be very skeptical of any brand that tells you that their design – no matter how many links, sliders or dangling parts it has – is too revolutionary and has benefits that can’t be seen in any motion graphs, or that they manage to bypass the usual compromises . Commenting is all about compromises.

But to answer the crux of the question, do these graphs tell the whole story of how the suspension system works? of course not.

First, there’s a lot more to unpack in these zigzag lines than sometimes gets to be unpacked. People often quote a single number—like the percentage of squat resistance when slouching, or the change in leverage ratio between the start and end of a flight—as if it tells the whole story, but there’s a lot more to it than that. For example, file regression From the anti-squat curve it may affect how stable the suspension is under force, or the shape of the leverage curve as it swings between the start and end points may be more important than the leverage numbers at these two points.

Another often-forgotten caveat is that squat resistance and anti-rise are dependent on the bike’s center of gravity and the rider, so if you’re comparing the anti-squat curves of two different bikes, they can’t be compared directly unless they are both computed with the same set of assumptions for the COG center. The tire size, sequence, and sprocket selection should be the same to make things fair. But with all those caveats and subtleties, the kinetic graphs describe the suspension Connectivity excellent.

But how the suspension behaves and how the bike actually rides depends on much more than the attachment of the frame. The choice of shock and its damper language are arguably more important—in the case of Marine Wolf Ridge, the subtle damping melody is perhaps the main reason the suspension performance was unusual and divisive in opinion, rather than the slider. Meanwhile, geometry, wheel size, and components can also affect how much harshness is passed on to the rider. All of these factors and more interact with each other in a way that is too complex to fit into any graph. This, I hope, means that we bike reviewers will still have a job for the foreseeable future.


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