An admitted shoe geek waxes philosophical about running, triathlon, and life in general.
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Tuesday, March 20, 2018

Why it works -- Some Kinekt details from my perspective

To say I was enamored with the Softride system is to invoke the British gift of understatement. I've had three dedicated Softride bikes, by two different framebuilders.

I raced them. On the road and on the track. In a transitional era when bike racing and what constituted an acceptable machine was still steeped in tradition, and anything "not normal" was derided. Constantly. But in spite of being on something so unusual (and before they were deemed "no longer legal" for international competition), I did fairly well for myself.

I've now been riding on a Kinekt seatpost for a little over a week. Well, actually, I've put in five rides on it. Three days in a row over the first weekend (Aaaaaah!), then a week riding my single-speed monster-crosser without the Kinekt, a weekend of trainer rides (and Netflix)... I brought the Kinekt to work to put on that bike to ride over VERY familiar terrain (almost 40 hours so far just this year on these trails/gravel roads).

 Oh, yes! It made this:

feel more like this:

But I'm not so much wanting to gush about how good it feels, rather I want to take a little time to expound on why I think it works so well for gravel and even road riding.

Most of what hits you on gravel is fairly low amplitude single bumps, non-rhythmic stuff going over embedded small rocks, sticks, small pot-holes-in-the-making, and the occasional grass clump. We're not talking about the big stuff that you should be avoiding or jumping anyway (your tires will thank you), but the constant undulations, pokes, prods, and little jolts that you unconsciously (or consciously in many cases) unweight the saddle to roll over.

It's exactly this kind of constant upsetting in which the Kinect post shines. There are two reasons for this, in my opinion: Direction of movement, and active nature.

Direction of movement

When the rear wheel rolls over a small bump, the entire bike rotates around an axis. Initially one might think that the point of contact of the front tire to the ground is that axis, but the entire bike is not a rigid body. The wheels rotate, or from another perspective, the bike also around the wheel at the hub. The axis of the bike when the rear wheel hits a bump is at the front hub rather than the front tire's contact patch. The rear hub motion is vertical, only because it is at a horizontal position relative to the front hub. The saddle rigidly attached to the frame moves in an arc upward and slightly forward. To counteract this in an ideal manner, the suspension motion must be down and slightly rearward.

Which is just what the Kinekt does. Unlike telescoping systems, the parallelogram moves the saddle in very nearly the ideal direction.

Active nature

The second reason the Kinekt works so well on the small, constant hits is its active nature. Shock-absorber based suspension systems rely on seals and dampers to keep the suspension medium (air and oil) in the fork and working. These seals produce friction -- resistance to the suspension doing its job. Additionally, dampers slow the motion of the shock so that it doesn't "pack up" or over-rebound. This is great on the big hits, but a shock system tuned for hits like that is fairly inactive over small stuff. And that's the nature and need in the mountain bike world. For gravel riding, the hits are smaller, and you want a suspension that lacks the "stiction" (static friction) of an air/oil shock based system. You want it to be active on the small hits.

Again, the Kinekt shines in this regard as well. Where the Softride worked as essentially a big leaf spring (with an elastomer layer for damping), the Kinekt uses coil springs inside the parallelogram, and extremely little in the way of friction. The result is a very active suspension that responds to the small bumps, with enough travel to take up most of the normal little stuff that you'd ride over.

The big hits? Potholes, large, sharp half-buried rocks? Still go around them or jump over them. You'd be pinching a tube or denting a rim anyway, so just don't go there. The Kinekt won't save you from reckless abandon or sheer lack of smarts.

And that's all well and good when the pavement runs out. But how about road riding? 

Well, again, the very active nature of the Kinekt system reacts to even the smallest of vibrations, so all those chip-sealed backroads feel more like that newly laid asphalt on the main highway. All that little buzz is something that you don't even notice until it's gone, and you wonder how you didn't realize what it was doing to you. It's fatiguing. Taking it away doesn't make you necessarily faster -- in the first hour. But as the ride gets longer, the difference is very apparent.

So... Still a very enthusiastic two-thumbs-up vote. 

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