2012 Blacx Jewel magnetic air dropper height adjustable seatpost for xc am fr dh mountain bikes with detachable remote

Barcelona’s Blacx has created what looks to be a superb height adjustable seat post. Their 2012 Jewel looks as though it addresses the spectrum of common concerns among drop post users, including rotational play, breakage and durability.

The main cylinders, clamp head and rail clamps are all machined from 7075-T6 aircraft grade aluminum alloy, and the upper cylinder and seatpost clamp head are a single piece, nothing’s bonded in. This not only makes it lighter, but should make it stronger, too. The clamp mechanism allows for separate fore/aft and tilt, with all bolts easily accessible through or under the saddle when installed. The clamps are designed to work with round or oblong seat rails, and they’ll also work with I-beam saddles.

The drop mechanism is magnetically actuated and moved by air pressure, the speed and strength of which is easily adjusted by changing the pressure through a bottom-mounted Schrader valve. Internally, they’ve brought out the big guns with Igus and Quadrant bushings and SKF and SIMRIT seals. By using three parallel keys slotted into the post and tight tolerances, they’re claiming zero rotational play and fore/aft flex. The main tube is reinforced to prevent binding from over-tight seatpost clamps, another somewhat common complaint. By combining all that with PTFE-infused Quadrant polymers and Kluber silicone oil, they’re promising sharp, precise and smooth operation. For life. That’s a tall order for a component typically known to develop play.

Drop in for specs and more details…

Shown above from left to right are the XC, AM, AM+ and DH posts. They use preset drop indents (like the Specialized posts) rather than free floating adjustments (like the Rockshox Reverb). Quick specs:

  • XC – 0mm/30mm/80mm drop – 375mm long – from 479g
  • AM – 0mm/40mm/110mm drop – 375mm long – from 501g
  • AM+ – 0mm/45mm/125mm drop – 395mm long – from 519g
  • DH – 0mm/70mm – 375mm long – from 471g
All four are available in 30.9 and 31.6 diameters with black, silver, gold, red or blue anodized collar, lever and clamps.

2012 Blacx Jewel magnetic air dropper height adjustable seatpost for xc am fr dh mountain bikes with detachable remote

In addition to the solid construction, two particularly innovative features stand out. The first is a detachable adjustment cable, which should make installation super easy and reduce the likelihood of major damage in an accident. As nice as this is…

2012 Blacx Jewel magnetic air dropper height adjustable seatpost for xc am fr dh mountain bikes with detachable remote

…the under-the-bar remote thumb button might be the best feature of all. Ergonomically, it allows you to keep your full grip on the handlebar, a particular bonus when you’re dropping your post at the last minute over a sketchy precipice. Those in the know will appreciate the “duh” ingenuity of this immediately and I imagine plenty of other product designers smacking the “why didn’t I think of that” onto their foreheads right about now. It’s a flexible design, though, so you can run it above or below, left or right without swapping mounts. The only downside? You’ll have to slide your grip, shifter and brake lever off to install it.

The Jewel is designed and made in Barcelona, Catalonia by Blacx.


  1. Is this the company that is finally going to do the dropper seatpost right. I like what I see. I love that the cable is fixed on the slider so it doesn’t move with every adjustment. I would like to find out where I can get these. I’m going to do that right now!
    Thanks bike rumor

  2. love the idea these posts….do people actually use the step adjustments? I would think either full up or full down would be the best right? i honestly don’t know, never used one, so if you have, can you explain?

  3. The magnetic operation is interesting and I see that they are putting the cable on the fixed section of the post like the Kind Shock LEV. I don’t see much special about the remote compared to the KS remotes that double as ODI grip clamps to save bard space, or the Rock Shox remote that fits on a Matchmaker mount.

  4. As to full up/full down, a middle setting is really nice for rolling terrain where there are steep and tech sections, but also sudden climbs, etc. I prefer the infinite adjust of the Reverb personally, but the three-setting is fine once you get used to it.

    would love to try one of these posts

  5. The first version of this post had huge problems- but kudos for them to keep trying and continue to refine the product. I hope this version works out.

  6. Nice.
    They look like serious players in the field.
    The only problem is… well… it’s like for all the others: we’ll know only next year if they are really great products.. or not.
    Time is the real test for adjustable seat posts… The “For life” warranty seems to mean that they are game, but I am still not ready to have my seat post shipped to their customer service every 2 months…

    Wait and see, folks… Wait and see…

What do you think?