Pacenti PDent

Words Pete Roggeman
Date Apr 19, 2015

We all have a seat on the short stem bus, right? Stubbies give us quicker handling with less steering input, the ability to use wider bars for more control – short stems are sticking around for good reason. They also complement the benefits of long top tubes: a steeper seat tube puts you in a better pedaling position, a longer front center makes you more stable, and your fore/aft position will leave you more centered and less prone to go OTB.

Pacenti-3

Aggressive trail bikes are designed around long top tubes and short stems, but Pacenti wants to figure out the limits of each.

Bike geometry is a complex series of interrelated dimensions, but short stems and long top tubes do an unusual number of good things for handling and bike fit, so Keith Pacenti’s pursuit of the longest possible top tube required the shortest possible stem, and vice versa. His problem was the one thing that has stood in the way of testing the inner limits of stem length: the steerer tube.

So he tested his idea by cutting a hole in a bar and butting it up against the steerer, held in place by a short stem. The commercialized version of that design is called PDent, and it features a dimple in the back of the bar that allows it to rest snugly against the steerer tube when mounted. Simple and clever. One downside of the system is that your bar’s dimple has to correspond to the stem length you want to run – the shorter the stem, the larger the dimple, and if you want to switch your stem length, it’ll require a new bar. PDent bars can be mounted in conventional length stems, but if you’re experimenting with short stems, it’s unlikely that would ever be needed.

The dimple is compatible with different head tube angles and includes a few degrees’ worth of fore/aft adjustment while you’re fine tuning your cockpit’s fit. Bonus time: lining up your bar just became a no-brainer. For his next trick, maybe Kirk can come up with a method for easy stem alignments…

Pacenti_040715-2_hi

Looks about right, doesn’t it?

 

Pacenti_040715-3_hi

Top view of the Pacenti PDent’s dimple.

Pacenti thinks that optimal stem length is somewhere between 12mm and 30mm, the shortest currently available without mounting on top of the steerer tube, which sacrifices handling. If you go shorter than about 10mm he figures your hands will be too far behind the steering axis and it’ll feel like you’re holding a tiller.

Pacenti PDent 107

The bar/stem/steerer interface area is nice and clean. 31.8mm bars are a bit easier to work with since the dimple doesn’t have to be as large, so we may see licensees sticking with that standard rather than 35.

Pacenti was showing carbon bar PDent samples, and of course the question of strength came up. Their FEA testing showed that the dimple doesn’t create any stress riser issues or other issues of concern.

So does that mean you will have to buy a Pacenti bar and stem to take advantage of PDent? The answer is no. It will be protected technology but Pacenti will be licensing it. We’ll see a test sample later this Spring, and it’s expected to be available for purchase later in 2015. Pricing will be competitive with other carbon bars and machined stems on the market.

Pacenti PDent 105

Got a Stubby chubby, or is 30mm short enough for you?

Trending on NSMB

Comments

john
0
John  - April 19, 2015, 10:50 p.m.

Can't get the bar rotation wrong can u

Reply

etal
0
etal  - April 19, 2015, 9:50 p.m.

I just don't get it, they put all this effort in putting a 5mm dent in the bar and then do a 20mm forward sweep on it. Wouldn't it be easier to curve the bar differently to get the same hand position instead of requiring a special bar & stem combo?

Reply

cam@nsmb.com
0
Cam McRae  - April 19, 2015, 11:06 p.m.

Forward sweep? There is no unusual sweep on this bars in my understanding.

Reply

etal
0
etal  - April 20, 2015, 1:14 a.m.

Just look at the top view picture, the stem area sits behind the frontmost part of the bar.

In the end the length of the stem does not matter, the only thing that matters is the location of the hands in relation to the steerer tube. You could have gotten exactly the same rider position and steering characteristics by having the stem a little bit longer and bending the bar differently.

Reply

CoilAir
0
CoilAir  - April 20, 2015, 9:30 a.m.

There are off-road moustache bars out there, etal. If you want to ride with that, more power to you. I think most MTBers much prefer the traditional aesthetics of a "normal" handlebar.

Reply

agleck7
0
Agleck7  - April 20, 2015, 10:50 a.m.

I think that's an illusion with the rise, not sweep. Look at the rider pic. Looks normal to me

Reply

pete@nsmb.com
0
Pete Roggeman  - April 20, 2015, 10:54 a.m.

That photo is just a bit deceiving. It's not shot looking straight down, so what looks like a forward sweep is actually the rise and sweep.

Reply

nomad
0
Nomad  - April 19, 2015, 8:06 p.m.

Forget the gimmicky bar/stem, I want to know how that Avvy shock is working out!

Reply

pete@nsmb.com
0
Pete Roggeman  - April 20, 2015, 10:55 a.m.

I think it's a Push. In any case that action shot was supplied by Pacenti - we don't have a test sample yet.

Reply

nomad
0
Nomad  - April 20, 2015, 1:32 p.m.

Whoops, too late for my brain I guess. Looking forward to the Push review, hopefully you guys can get your hands on one.

Reply

Please log in to leave a comment.