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Product Review: Redshift ShockStop Suspension Seatpost

My first review of a Redshift product was for their ShockStop suspension stem. At the time the ShockStop suspension seatpost had just been launched on Kickstarter. I pre-ordered one and have been using it for a few months now. It was on my bike during the 280km IIUM Endu-ride at the end of last month.


One knock against suspension seatposts is they are not particularly attractive. The Redshift ShockStop is fairly minimalist compared to, from left, the Cane Creek Thudbuster ST, the Kinekt-BodyFloat, the Suntour NCX and the Specialized CG-R suspension seatposts.


The ShockStop seatpost is made of 6060 T6 aluminium alloy. It is 350mm long and 27.2mm in diameter. Shims are available to fit 30.9mm or 31.6mm seat tubes. The saddle clamps are compatible with 7mm round and 7x9mm oval saddle rails.

This seatpost weighs 497gm.

Photograph courtesy of


The 35mm of suspension travel is provided by a main spring. A second inner spring can be combined with the main spring to provide a stiffer spring rate, up to the rider weight limit of 110kg.

The spring stiffness can be fine-tuned by adjusting the preload plug at the bottom of the seatpost.

Diagram courtesy of


Installation is straightforward. A comprehensive set of printed instructions comes with the seatpost. An installation video is also available on the website.

Graphic courtesy of

Ride Quality

The Redshift website says that the ShockStop suspension seatpost “lets you float over rough terrain – ride further, faster, and more comfortably on the bike you already own.”

This seatpost delivers on that promise. Saddle movement is fluid, without any jerkiness as it moves through the 35mm of available travel. This creates a plush feel that is effective at isolating the rider from vibrations and larger impacts.

The four-bar linkage keeps the saddle angle constant throughout the range of movement.

A nice touch is a fender or cover that attaches magnetically to the rear of the suspension linkage. This keeps the moving parts of the linkage and saddle clamp bolts clean when riding on wet roads.

Animation courtesy of


The Redshift ShockStop suspension seatpost is well-engineered, easy to adjust and has a smooth and impressive suspension action you can tune to your own personal preference.

I like this suspension seatpost so much that I bought a second one for my other bike.

Purchase online at Redshift.

FSA K-Force Light SB25 Seatpost

Posted on

Seatpost In Action

Graphic courtesy of Road Bike Review

I have written a few posts about my Alchemy Eros.  Starting with A Bicycle for the Cognoscenti Adventure, followed by My New Best Bike:  the Alchemy Eros, and 4,000 km / 2,500 mi Update:  Alchemy Eros.

A common theme in the two later posts is that the trade-off for a stiff and sharp handling titanium frame is a ride that is sometimes jarring.  I have owned, and still own in the form of a Ritchey Break-Away Road Ti / Carbon, Ti bicycles that are more comfortable.

I lived with the tradeoff between frame stiffness and comfort until I read an online article in VeloNews titled Getting the Most From Your Post.  First published in June 2012, the article is somewhat dated, but still relevant.  The article attempted to determine the role the seatpost plays in rider comfort.

In its typically thorough fashion, VeloNews set out to answer this question by testing 14 seatposts of different materials, setback and design philosophy. At Boulder’s Microbac accredited test laboratory, they measured vibration damping over small bumps with an accelerometer, and they measured linear deflection (flex) under body weight in two dimensions.

The winner was the FSA K-Force Light SB (Setback).  VeloNews judged the FSA seatpost to be the best choice for long road rides.   The FSA seatpost has excellent vibration damping, which makes it noticeably more comfortable, especially on long rides, dirt roads, or concrete or asphalt with lots of small cracks and expansion joints.

The seatpost that came with my Eros is the Ritchey Comp Carbon.

Ritchey Carbon Comp

Photograph courtesy of Ritchey

This seatpost was not one of those tested, but three other Ritchey seatposts, the WCS Carbon SB, the WCS Aluminium SB, and the WCS Carbon Straight, are among those in the Velonews review.  The Ritchey seatposts came in sixth, tenth and last respectively.

The Comp Carbon sits at the lower end of Ritchey’s seatpost offerings.  I thus assume that it would score even lower than its siblings on the VeloNews test.

Eager to soften the ride of the Alchemy Eros, I bought an FSA K-Force Light.

FSA K-Force Light

Photograph courtesy of Full Speed Ahead

I have the version with the same 25mm of setback that my Ritchey Comp Carbon has.  For purely aesthetic reasons I opted for the black and grey graphics rather than the red and white.

VeloNews had discovered that a setback post will give you greater pedaling efficiency and more high-frequency vibration damping.  My usual routes don’t have big bumps, where the greater flex of a straight seatpost is an advantage.

I have ridden 370km / 230mi on the FSA K-Light.  The ride quality of my Eros has noticeably improved.  Even with 10psi more air pressure in each tire.  There is much more vibration damping now.  My Eros rides much more like I would expect a Ti frame to ride.  So my qualitative impression so far matches the quantitative findings at VeloNews.

I have a 240km / 149mi ride, split over two days, this weekend.  I am looking forward to a more comfortable long-distance ride than I have had before on the Alchemy Eros.