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Fox DOSS Dropper Seatpost

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Fox DOSS Dropper Seatpost

Perfectly Positioned to Ride Any Trail

The all-new D.O.S.S. seatpost complements Fox's CTD ride dynamics system with on-the-fly seat-height adjustability, so you're perfectly positioned to tackle any type of terrain.

CTD 3-Position Integration

Gain complete ride control at your fingertips with the lever-actuated, three-position D.O.S.S. seatpost. It syncs with front and rear suspension settings Climb, Trail, and Descend - for instant performance optimization based on the terrain.

The easy-to-find middle position dual levers and the internal positioning system make it easy and automatic to find middle Trail position every time.

  • Provides 4-position mounting options: left/right, above/below, handle bar
  • Fast and easy reach accessibility
  • Dual levers make it easy to find middle trail position every time
  • Adjustable reach
  • Dual internal cam system for easy travel-setting activation
  • Air pressure is used to adjust the speed return (10-25 psi)
  • Saddle clamp has a no slip, 2-bolt design

If you're replacing your seatpost you may want to get a new saddle too. Take a look at our entire selection of saddles here.

Due to manufacturer restrictions we can only ship this item within the U.S.


Model D.O.S.S.
Material Alloy
Sizes 30.9mm / 31.6mm
Type/Application XC/trail/AM
Length Options 4", 5"
Cable Routing Left or Right
Travel Modes Climb, Trail, Descend
Weight 1.37 lbs / 620g (30.9mm x 5")

Showing Questions 1 of 1

Q: What is the length of the tube that inserts into the frame? I have a lrg trek 9.9 ssl (FS) from 2012. I need to know if it will fit in length wise . (4 inch post )

A: Overall length is 335mm, the minimum insert is 95mm.

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Best Purchase - Dec 31, 2015

1 2 3 4 5
5 out of 5 stars
Astoria, OR

I have the 30.9 diameter 5" dropper version. This post has been flawless. It is easy to maintain and set up. There is a little cable-lag felt with the lever, but the post still responds very quick. I am only running about 12psi in mine and this is perfect. This has been the best purchase for my bike and it truly is a FIVE star rating. The post is solidly built, continues to work the same as the day installed and is reliable. When looking for a dropper this and the Thomson were the only ones with zero mechanical issues. Yes, the lever is large, but when mounted under it looks fine. The bottom line is this post is great.

0 out of 0 people found this review helpful
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Simple and Solid - Aug 22, 2015

1 2 3 4 5
5 out of 5 stars
Astoria, OR

This post is great. It is fairly easy to set up. If routing semi through the frame; I recommend setting up the cable housing then feeding the cable. Get your measurements, double/triple check, mark and cut. The cable is retained securely by the set screw. The seat is held secure and the the overall travel is buttery smooth: better than the Specialized Command post and at least as smooth, if not smoother than the Reverb. I am very happy with this post! Lastly, ensure that you do pump or check the air psi with the valve facing up. If you do not some of the lubricating oil will come out.

3 out of 3 people found this review helpful
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A must buy! - Apr 27, 2014

1 2 3 4 5
5 out of 5 stars

This make a good mtb great! i had everything else on the bike, but finally had to get the dropper post. it works good takes time to set it up properly and i have to run like 45lbs pressure to get the post to come all the way back up, but ill never ride without one now :)

0 out of 0 people found this review helpful
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Love riding with the DOSS dropper - Sep 10, 2013

1 2 3 4
4 out of 5 stars
Denver, CO

I've been riding this dropper post for six months and I love it. The one-inch drop position is great for mild downhill sections and mostly downhill rolling trails. The four-inch (all the way down) position works great for steep drops and fast cornering. I put 12 PSI in it and it works great. I've demo'ed bikes with other droppers and this one is smoother and easier to move down. It's very solid. I really like the two-bolt seat attachment, totally rigid. The only thing keeping me from giving it 5-stars is the clunky remote lever. I made my own mounting bracket from an old brake mount and it works so much better. I don't even use the black lever. After a few rides, I got the hang of just using the silver lever to move it into either position and it works great.

5 out of 5 people found this review helpful
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