Product Test: Fox D.O.S.S. Seatpost

Remote control: The D.O.S.S. seatpost in climb (full extension) and descend mode. The actuation cable takes a ride down with the saddle, making cable routing critical.

A dropper seatpost (a seatpost that can be lowered on the fly without tools) from Fox has been one of the most anticipated products since…well, since we saw a prototype almost three years ago at Interbike. The $439 Fox D.O.S.S. (Drop On Steep Stuff) seat-post is finally a reality, and Fox is taking this so seriously that they changed the name of their company from Fox Racing Shox to Fox, Redefining Ride Dynamics, to reflect that they no longer think of themselves as a suspension-only company.

Thumb-wrestling: The remote levers are big and easy to find. The lever interface with the rider required a deliberate and calculated effort.

Tech features:
The Fox D.O.S.S. is available in either 30.9- or 31.6-millimeter diameters with your choice of a 4- or 5-inch saddle-height drop. Keeping consistent with the 2013 CTD suspension technology, the D.O.S.S. had three height settings: climb (full extension), trail (about 1.5 inches lower than climb) and descend (fully slammed). The remote lever has a split perch (so you don’t have to remove the brake and shifters to mount it), and it can be positioned on the left or right side of the bar. The saddle clamp is a two-bolt design. Air pressure, added through a Schrader valve at the bottom of the post, regulates the rate at which the saddle returns. Our 30.9-millimeter D.O.S.S. in the 5-inch drop version weighed 1 pound 6 ounces, including all the mounting hardware, cables and remote levers.

Field Test Results:
The Fox D.O.S.S. seatpost mounted easily to our Pivot Mach 5.7 Carbon, as did the remote lever. Fox’s saddle clamping system offers infinite saddle tilt adjustment and never allowed our WTB saddle to slip during testing.

Two-tone: Push both the black and silver lever to drop to trail mode, or push the silver lever to drop to descend.

The remote actuation levers are the largest we have come across in our dropper seatpost testing—and the worst ergonomically. The two-lever system is not intuitive, and neither lever allowed our thumbs to actuate them with a smooth and natural motion.

The two drop heights are not a deal-breaker, but this system is less convenient than a dropper post with infinite height settings. We did find ourselves in the middle mode from time to time (that had little to do with “trail” mode riding), but most often we used full extension for all pedaling sections or fully dropped for descending. When in fully slammed mode, the actuation cable moves down with the saddle, so care needs to be taken in its routing so that it does not contact the rear wheel or suspension. Fox refuses to offer a product that is not 100 percent reliable (their suspension is a testament to this).

We assume the levers are so big because Fox feels this is necessary to meet their reliability goals. That is to be commended. If you are sick of using a dropper post that explodes every three months, develops play in a matter of weeks or has a remote that loses its touch, the D.O.S.S. will keep you dropping instead of shopping. Still, we need a lever that is smaller and interacts more naturally with our thumbs. Once you put a dropper post on your bike, you will want to use it a lot. The Fox levers make that harder to do.

This review originally appeared in our November 2012 issue. Subscribe to MBA here.