Tech features: The Niner RDO Carbon seatpost is designed to deflect, offering what Niner claims is a small degree of suspension. The RDO (Race Day Optimized) seatpost’s monocoque design is made lighter by eliminat- ing bonded sections. Niner claims that the internal structure of the post is designed to disperse impact energy throughout the entire structure, damping trail vibrations and increas- ing fore/aft flexibility to absorb shock. The seat clamp is a two-bolt clamp with zero setback. The RDO is available in 27.2x400-, 30.9x370- or 31.6x400-millimeter diameters and lengths. One 30.9x370-millimeter post with all-mounting hardware weighed 7.1 ounces, or more than half an ounce less than Niner’s claimed weight. The post carries a Niner C5 Carbon warranty (good for five years, even if you race). 

Field test results: We had recently tested the Niner Air 9 RDO (September 2012), but this bike uses an all-carbon frame that is very comfortable and compliant to begin with. We felt a dual-suspension bike would make it 

difficult to isolate the advantage (or lack of advantage) the seatpost was bringing to the party. We settled on slipping a 27.2x400- millimeter RDO seatpost into an aluminum- framed Specialized Carve Pro hardtail 29er. The saddle (a Specialized Body Geometry Carve SL) mounted easily, and the two-bolt clamp allowed for infinite saddle-tilt adjustments.

The ride quality difference is remarkable over the stock aluminum seatpost. It is not a subtle difference that would require a skilled profes- sional to sense. A beginner would be able to feel the difference. We won’t go so far as to say the RDO adds suspension to the bike, because the saddle height doesn’t change a measurable amount when the seatpost is working. What it does add is a lot of forgiveness to the bike’s rear triangle. This can be felt while hammering along in the saddle, as the seatpost muffles trail chatter. The best attribute of the RDO is revealed when the rider tags a flat-edged bump at speed. The jolt the rear end sends to the rider who didn’t get out of the saddle fast enough never arrives through the RDO.

When asked what is the best-value upgrade, we usually suggest tires, handlebars or pedals. Scratch that. To riders of aluminum hardtails (with 29- or 26-inch wheels) or low-priced carbon fiber hardtails (that can be way more brutal than an aluminum frame), we would say that buying the $200 RDO seatpost is money well spent that will save some weight and keep paying you back with every mile of singletrack. It is a must-have for riders with back pain issues.