Sea Otter 2015: Pacenti PDent bar/stem system

by 13

Before the Sea Otter yesterday, there was a select meeting of a dozen people in a hotel room away from the Sea Otter. There was a mix of journalists and big name OEM bar and stem (and fork) manufacturers for Kirk Pacenti’s big reveal.

Pacenti’s PDent system in the flesh

You might know Kirk’s name from his championing (or even pioneering) of the 650B tyre and rim size before the big names caught on. This time he promised to shake up the bar/stem world in the way that the 27.5in wheel shook up the wheel and tyre world.

Tested in the real world too, not just on the CAD machine
Wide clamping area with nothing going on in the middle, stress-wise.

Kirk’s thing is a ‘surely someone must have patented this before, but no, they don’t seem to have’ simple idea to shorten stems beyond the 32mm current minimum length before the bar touches the steerer.

Yes, you can patent a dent.

Companies, like Mondraker in particular, have been playing with shorter and shorter stems, but they have always had to raise the handlebars up so that they sit on top of the steerer. Kirk’s idea is to put a dent (anything up to 15mm) in the back of the handlebar to allow the bar to sit closer and shorten the cockpit even further. This allows a responsive steering bike and keeps the rider’s weight more balanced between the wheels on today’s longer and longer top tubes.

You might think that it’s a highly stressed area, but the handlebar makers we spoke to there seemed to agree that between the stem bolts, there’s not a lot of stress – it’s only outside the stem where things start moving around. So putting a dent there is completely fine – and in fact Kirk’s early ‘don’t try this at home’ experiments involved a chunky block of aluminium as a stem and a handlebar that he’d simple holesawed a chunk out of to create the dent.

‘It was this big!’ Kirk showing how he loves a 26in top tube.

Pacenti’s idea is to license this design to bar and stem manufacturers so that everyone can use it. His company will also be producing a range of bars and stems in the near future – and we hope to get a testable sample in the next month or so to see if the benefits are as great as Pacenti claims.

Will we see them on bikes next year? That’s a distinct possibility. One of the turn-offs of Mondraker’s zero stem idea has been the extra stack height, the need to chop down the steerer exactly, and the gopping visual look of the thing. Pacenti’s idea allows a normal looking stem, the ability to fine tune the ride-height with stem spacers and a range of lengths from 15mm (or even shorter) to 29.9mm (where his patent runs out)






Support Independent Mountain Bike Journalism

Like what you are reading?

Bookmark us now and come back again.

Try out Singletrack membership today from only 49p per week

(49p is the weekly equivalent price of the £25 annual digital membership)

Support Independent Mountain Bike Journalism

Singletrack World is a largely reader funded community with over 6,000 members trusting us for their mountain bike news, reviews, adventures, advice and big views.  

Try out Singletrack membership today from only 49p per week

(49p is the weekly equivalent price of the £25 annual digital membership)

Chipps Chippendale

Singletrackworld's Editor At Large

With 22 years as Editor of Singletrack World Magazine, Chipps is the longest-running cycling magazine editor in the world. He started in the bike trade in 1990 and became a full time mountain bike journalist at the start of 1994. Over the last 30 years as a bike writer and photographer, he has seen mountain bike culture flourish, strengthen and diversify and bike technology go from rigid steel frames to fully suspended carbon fibre (and sometimes back to rigid steel as well.)

More posts from Chipps

Comments (13)

    Do you get any room to rotate the bar back and forth a bit to fine tune position?

    Or is it locked in place by the dent?

    It looks like the dent is a smaller radius than the steerer, so the bar is rotatable. I would imagine that the steerer and bar stay out of contact anyway to stop them rubbing against each other.

    Well done Mr. Pacenti I say

    A wider deeper dent than the corresponding stem would allow you to rotate the bars. Depends on how much the bar can be dented before they become too weak though.

    off to patent a steerer with a dent in it….

    “off to patent a steerer with a dent in it….”

    Competing standards, lol.

    How deep a dent is needed to use with a 15mm stem? Is it the dent shown? Or deeper?

    And how short a stem could you use with a 25.4 or 22.2mm bar, without deforming it near the clamp?

    That’s a 6mm dent in the pic, which would allow a 25mm stem. A 50% dent of 15mm or so is still possible without unduly weakening the bar (reckons Pacenti anyway). Smaller diameter bars were talked about, but it seems we like our 31.8s.

    Would it not be easier to build bars and stem as one unit? I can’t understand why mondraker haven’t done this.

    [ quick bit of maths ]

    So, dent shown allows for a 25mm stem with a 31.8mm clamping area. Using a 25.4mm clamping area without a dent, which has already been proven to work fine on mtbs, allows a 26mm stem. I know which seems the obvious answer to me.

    Going shorter… a 15mm dent in a 31.8mm bar seems a bit crazy… although I’m sure it can be made to work fine strength wise in both metal and carbon easily enough. Just a bit counterintuitive.

    Darn. My guess at 32.5mm bars didn’t happen.

    It’d be ultra cool if these dented bars were combined with andyl’s dented steerer. 😉

    Kelvin, a 15mm dent allows a 17mm stem. (Minimum normal stem length with a 31.8 is 32mm or so.) and that’s where Pacenti reckons the sweet spot of stem length is.

    YAY! I want one.

    I don’t mind this in theory… but saying that the sweetspot is directly within your newly patented standard does grate a bit. C’mon admit it, anything with +/- 150mm will be fine 😉

Leave Reply