Over the four installments of the deflection diaries, I’ve shared my experience with Redshift Sports’ ShockStop suspension stem, and it’s been quite favorable for the most part. The inherent limitation of the design, though, is that it’s a stem – it will only ever offer suspension at the front of the bike.
The boffins at Redshift Sports have taken notice, and listened to the demand for a counterpart solution to tame bucking at the rear end. They came out with the ShockStop suspension seatpost, which they told me about a few days in advance of today’s launch. They were nice enough to send me photos to share with you, too.
Rear view of the ShockStop seatpost, showing a bit more insight into the pivot mechanism.
REFINING AN EXISTING IDEA
Baking suspension into a seatpost isn’t a new concept, judging from the many designs that have come before. Perhaps the most popular example is Cane Creek’s Thudbuster, based around a mechanical parallelogram linkage damped by an elastomer.
Another school of thought takes advantage of the benefits of carbon fiber composite as a material. Hyro’s own carbon composite seatpost is a Giant D-Fuse type, the flat rear side shaped to promote flexion. Perhaps Canyon’s VCLS 1.0 and 2.0 seatposts, based on an Ergon design, are the modern poster children for this. This design basically splits the seatpost into two pieces, joined at the saddle clamp and at the other end, turning the entire assembly into a leaf spring and offering greater deflection.
Redshift takes the basic design concept of their own ShockStop stem and this time applies it to the seatpost. As before, there is a mechanical pivot providing the motion, and there is a damper controlling and keeping unwanted motion to a minimum. In this case, instead of resorting to elastomers, the damping comes courtesy of a selection of coil springs of different stiffnesses, hidden within the seatpost itself, which the user can swap out for ride and sag tuning. In this particular aspect, it’s similar to the Specialized FutureShock suspension cartridge for steerer tubes, which ships with three coil spring options for tuning.
Installed on an older Specialized Roubaix endurance road bike.
Similar to the ShockStop stem, the hardware here is hidden in a rather standard, round aluminum seatpost 27.2 mm in diameter, which means if your bike has a round seat tube accepting a seatpost at least that thick, it can mount right in. For bikes made around bigger seatposts, Redshift provides shims to make up the difference.
Installed on a Niner RLT9 gravel bike. The original aluminum RLT9 used to draw flak for flinty ride quality, so the ShockStop seatpost might be a good fit.
CROWDFUNDING COMMITMENT
By now, I’m sure you’ve heard of the many horror stories of projects that have resorted to Kickstarter or some other crowdfunding scheme…only to underwhelm with the finished product, or worse, not deliver at all and run off with the raised funds. So far, though, Redshift Sports has had a consistent track record of delivering on what they say. Their previous products, the ShockStop stem and the Switch Aero System, both began life as Kickstarter projects, were successfully crowdfunded, and are now both available at regular retail (which was how I got my stem).
It’s no surprise, then, that they’ve resorted to crowdfunding for this third go-around with the ShockStop seatpost. You can head down to their Kickstarter campaign page for more details. One interesting detail is that they’re offering backers a bundle where both ShockStop stem and seatpost are included – a “ShockStop system” if you will.
Fitted to a Gazelle Cittzen – a flat-handlebar commuter E-bike of the pedal-assist persuasion.
The ShockStop system – stem and seatpost – fitted to a Gary Fisher hybrid commuter bike.
UNFORTUNATELY FOR ME…
Hyro’s seatpost has a D-shaped profile, effectively rendering both it and the TCX seat tube as proprietary parts.
As this is a round 27.2 mm diameter seatpost, I can’t really take advantage of this design unless I get myself another bike. Hyro’s seat tube is specifically shaped to accept Giant’s proprietary D-Fuse seatposts, and Bino’s seatpost, while still round, is a comparatively massive, oversized 33.9 mm diameter common with Dahon and Tern folding bikes. Seeing video of the ShockStop seatpost in motion, it does look much more effective in providing deflection than Hyro’s D-Fuse seatpost.
SPECIFICATIONS
- 27.2 mm external diameter; shims available for larger seat tube diameters
- 6061 aluminum alloy, 3D forged and CNC machined, finished in anodized black
- 35 mm of suspension travel
- Rearward offset range: 0-22 mm; 10 mm at 25% sag
- Length: 350 mm
- Weight: 497 g
the accidental randonneur 