Cirrus Kinekt 2.1 Suspension Seatpost

Last modified: October 13, 2019

Cirrus Kinekt 2.1

Price: US$249
Weight: 575 grams (27.2mm x 350mm version)
Travel: 35mm

Gravel bike suspension

Some newer gravel bikes incorporate minor suspension in the front or rear of the bike. Suspension not only improves comfort and performance when venturing off-road, but may also be useful for people who stay primarily on paved roads but want to maximize their ability to ride further by improving comfort.

Fortunately, you don’t need to buy a new bike to get a small amount of suspension. Suspension seatposts are now available to take the edge off of bumps that can be added to almost any bike that uses a round seat tube, including the Cirrus Kinekt 2.1 post that I review here. I’ve previously also tested the RedShift ShockStop stem that does an excellent job of improving front-end comfort, traction, and even speed on certain terrains.

Suspension seatposts

Suspension seatposts have a long history, with various styles and designs available. The most basic design, often found on city bikes, uses a simple telescopic shaft. Because seat tubes are tilted towards the rear of the bike, this design is less than ideal for absorbing bumps, which act more directly up and down. In addition, the narrow shaft and off-axis loading often means that such posts don’t have good longevity.

Designs that allow the saddle to move straight up and down instead of in line with the seat tube are therefore preferable. They require a more complex parallelogram linkage, and are therefore more expensive, but several models are currently available.

Cane Creek ThudBuster ST

The Cane Creek ThudBuster ST has been around for a long time and my wife has used one on the back of our tandem with some success, although we were never entirely pleased with it because the simple elastomer damper gave a rebound that was too strong while at the same time not being that sensitive to smaller bumps. Different elastomers are available, but we never found one that gave an ideal ride. There is now a smaller and much lighter version available called the Cane Creek eeSilk.

Suspension that uses springs tend to perform better and be more tunable than suspension that uses elastomers. The three suspension seatposts with parallelogram linkages and adjustable spring dampers are the Cirrus Kinekt that I test below plus the RedShift ShockStop and SR Suntour SP12 NCX.

There are also some rigid seat posts that are designed to maximize the amount of flex and so offer some comfort while at the same time adding barely any extra weight. I’ve ridden two of the better-rated posts in this category, the Specialized CG-R (formerly Cobl Gblr) and Ritchey WCS Carbon Link FlexLogic.

I’ve found the suspension effect of these pivot-less designs to be very marginal compared to a rigid post. Differences in saddle padding and tire pressure are certainly far more noticeable than the minimal flex offered by such posts, so I rate them as not being that effective and certainly not comparable to a real suspension seatpost. Because of the subtle effect that these posts have, the best way to measure their performance is in the lab, which James Huang at BikeRadar did a few years ago.

Cirrus Kinekt 2.1