Pacenti Developed a 25mm MTB Stem using PDent™ Apr 21, 2015


MTB stems keep getting shorter, but there’s a barrier to ultimate stubbiness. That threshold seems to be around 30mm. Maybe that’s short enough, but for not for Kirk Pacenti. In his quest to push new ideas, Kirk has developed a patent pending PDent™ system, allowing stems to go as short at 15mm, with initial test products coming in at 25mm. Now, 5mm isn’t anything to brag about, but this is an interesting concept and an even moreso, something worthy of discussion.

Rather than paraphrasing Pacenti’s PR, I’ve pasted it in below, along with a few product photos.

Pacenti_040715-2_lowalt crop

Designer Kirk Pacenti is best known as the leading advocate for the game-changing 27.5” (650b) mountain bike wheel size. But when he addressed a packed house of MTB editors and industry buyers At Sea Otter last Friday, the topic was an entirely different kind of game-changer: breaking the 30mm stem barrier.

“Riders have been using shorter and shorter stems for years to improve handling in increasingly technical terrain” Pacenti explains. “And designers have started making frames with longer top tubes to accommodate them. But until now, the shortest practical stem available has been 30mm. Any shorter, and the handlebar runs into the bike’s steerer tube. Further evolution of frame geometry has come to a standstill due to the limitations of stem design.”

040715-5 Pat Pending CU

Enter PDent™, Pacenti’s patent-pending technology that offers an elegantly simple solution to the 30mm barrier. PDent features a dimpled bar allowing the use of stems as short as 12mm (the initial product is 25mm). As the PDent™ logo implies, dimpling the bar (D) lets is come closer to the steerer tube (P).

Pacenti explains, “In CAD terms, the “dimple” is a swept radial cut forming a pocket that allows the bar to wrap around the steerer tube. The dimple is designed to allow for a range of head tube angles (63° – 69°), plus several degrees of fore/aft rotation.

“By dimpling the handlebar we can make stems pretty much as short as we want. And unlike current sub-30 stems, we can also keep stem and handlebar heights just as low as traditional designs.”

PDent™ technology is already rolling out, with production samples later this month and full commercial availability by year-end. And Pacenti is already in discussions with several large manufacturers interested in licensing the technology.

“But the bottom line,” he says, is not just about PDent™ technology, or even about making shorter stems. It’s about opening doors to help designers create better bikes.”

  • Jaap

    Nice work-around, but it seems to me that the stem /steerer/fork design should get a rethink..

  • Harry

    Frame design is at a standstill because stems are too long? Bizarre statement Mr. Pacenti.

    • James Norman Woodley
    • boomforeal

      standstill is overstating it, but there definitely seems to be a wall looming. most companies are pushing the reach/top tube lengths on their 5-6″ travel bikes, and will eventually run into minimum stem-length requirements unless there’s a way to overcome bar/steerer tube overlap – which is what mr. pacenti seems to have accomplished here

  • gvnstewart

    Unless this dimple has a large enough radius for bar angle adjustment why not just make bar stem combos like BMX flatland has been for quite a while. A MTB enduro Cinelli integralter style bar-stem combo could look awesomely terminator.

    • boomforeal

      recent history suggests that the mtb industry likes continued incremental change, especially if it helps make year-old components obsolete. so next year they’ll be all over pdent, and the year after it will probably be integrated bar/stem combos. and the sheep will follow

    • gvnstewart

      Another thought… why not just make bars that s curve back. You could have a +35mm stem and a -35mm s-curve on the bars to give you effectively a neutral 0mm stem. No patent pending dimple required.

  • Jesse Rinyu

    So, how do I adapt this to work on the quill stem of my sweet, sweet Schwinn High Sierra?