Marzocchi’s Doppio Air System

“Doppio” in Italian literally means double, or perhaps dual. Hence, Marzocchi Doppio forks are dual air forks, having air in both legs and therefore lack coil springs. All operations of a fork, compression, rebound (decompression) and travel adjustment mechanisms, become functions of manipulated air pressures. So, to clarify there are three separate air chambers:

• Main compression air chamber (damping cartridge) - right leg
• Rebound air spring which also controls the travel adjust (increasing the rebound pressure conversely decreases the travel) - left leg
• PAR (Progressive Air Resistance) adjusts the ramp up rate towards the end of the travel, specifically also controlling the bottoming resistance for approximately the final 30mm-40mm - left leg

In my own humble opinion, the PAR chamber is perhaps the most significant advantage to the Doppio Air System by Marzocchi. By adding in this level of control, coupled with the TST damping system, Marzocchi now makes the most tunable forks on the market. The PAR chamber permits the rider to determine the amount of ramp up and bottoming resistance without ever adversely effecting the top end performance of the fork.

Forks Without Marzocchi’s PAR
Other forks, including Marzocchi hybrid forks (one side air, the other coil) do not have the capability to single out each function of their suspension. This means that when a rider desires to increase the bottoming resistance, they must now increase the air pressure in the main chamber. This results in the fork becoming more stiff at the top end, making it less small bump sensitive or less reactive for the initial amount of travel.

Marzocchi SL/Race Forks With PAR
The PAR chamber is advantageous really for any rider. There are three main groups however that particularly benefit from it though: light weight riders (under 140lbs.), heavier riders (185+ lbs.) & aggressive riders (who push the fork to its intended max). Lighter riders gain the HUGE advantage in that they can set up the Marathon SL for example, according to their weight, riding in the TST setting with the least amount of resistance for bump compliance without running the risk of bottoming the fork due to a linear or softer spring and still get pretty much all of the travel. Heavier riders can essentially do the same thing, but really crank up the pressure in the PAR chamber to provide more bottoming resistance than even a coil may be capable of, without sacrificing the loss of precious travel and making the fork too stiff over all. Aggressive riders compare rather closely to heavier riders in terms of PAR application. Again though, the key here is unparalleled tunability.

Marathon Race
I am not the person to get an unbiased opinion of this fork from. Normally, I make a concerted effort to approach each cycling component with as much of an open mind as possible. When it comes to this fork though, I just cannot wrap my mind around it. Not that it is a terrible fork, but I held on to the belief that Marzocchi wouldn’t ever make a fork based upon weight alone, and here they have! Shame on them! If you need or want a sweet 80mm air fork, hands down Fox is the ONLY way to go. I call it “Fox: The 80mm Advantage.”

Marathon SL
This is a pretty nice fork; light for a Marzocchi at around 3.7lbs, the tunability of Marzocchi’s TST (Terrain Selection Technology) and the ability to adjust the travel between 100mm – 120mm. These options make this fork a great in between fork, sandwiched between a Fox F80RLT and the Fox TALAS in terms of weight, function and intended use. Most race forks tend to reduce the amount of abuse you can dish out to it, thus limiting (in some sense at least) the amount of fun you can have. With this fork on a frame designed for a 100mm suspension fork, you can cheat the system a little bit by taking the travel up to 105mm-110mm for a tiny extra amount of cushion without really compromising the frame or its performance. For a light weight racing-ish fork, it is also capable of some decently aggressive riding and a whole lotta fun! The Marathon SL is an appropriate compromise to the racer who also likes to break it loose sometimes. Even still though, for a better performing fork, take a look at the Marathon XC, despite the heavier weight.

All Mountain SL
As a 130mm – 150mm all mountain dual air fork, it is certainly a contender, though not particularly my favorite option in this category. I lump this together with other options like the Rock Shox Pike Team, Fox TALAS RLC, Fox F130RLC, Marzocchi All Mountain 1 and the Z1 FR SL. My preference in this category would be to go with a Fox TALAS RLC if you’re dead set on getting an all air fork and want to stay more or less permanently at 130mm of travel. If you are attracted to the Marzocchi All Mountain SL for it’s travel adjustability because frequently you want to take it to the next level of aggressiveness, I recommend moving up to the Z1 FR SL which offers the same travel adjustability, the new high end RC2 cartridge specifically designed for all mountain and freeride applications, all as a fork that only comes with about 1/2lb. weight penalty. The 20mm thru axle and extra lateral stiffness are definitely worth it in my book – just too many benefits to pass up not moving up to the Z1 FR SL.

Z1 FR SL
Hands down the air fork I would get if I were looking for a 5lb. long travel dual air fork capable of maximum versatility IF you’re not interested in the ETA’s enhanced climbing abilities and do not see the need to stick with a coil spring. Over the All Mountain SL the benefits are just too great, especially with all the advantages of the 20mm thru axle (despite the hassles other riders claim) at such a minimal extra 1/2lb. weight penalty.

66 SL
Even though the concept of a dual air extreme freeride fork is something that I am fundamentally opposed to, this particular application is somewhat intriguing to me. As a 170 pound all mountain rider myself, I find it difficult to justify any of the 66 coil forks for a freeride set up because I’m simply not used to having that much fork up front. Not just travel, but stiff compression and such a burly chassis. With the exception of the 66 ETA, the 66 coil forks come standard with Marzocchi’s heaviest spring kit for the absolute most aggressive riding. Since I am not looking to optimize the stiffness of compression at either end, top end or bottom, the prospect of one of the other 66 forks seems a little daunting. Again, I’m merely providing my own perspective here.

Therefore a couple of my goals in approaching a freeride bike include keeping the front end less top heavy and maintaining small bump sensitivity while adding exponential lateral stiffness and bottoming resistance (just in case I decide to go big or accidentally find myself faced with a compromising situation). On a hard core freeride frame worthy of the Marzocchi 66 SL (given my background and style) I would not be so concerned with brake dive as I would on say a Z1 series fork with 150mm. However, when I decide to lower the fork down to 150mm, I have ultimate adjustability to make it feel like two different forks entirely. As a novice freerider, I would really take to the unparalleled tenability of the 66 SL, especially the travel adjust, so that I could dial in the exact geometry that I need for each situation.

For me, an extreme dual air freeride fork sounds crazy, but the idea of a Marzocchi 66 SL is just so intriguing to me, that I want to go get a frame right now just so that I can try it out. Just a little perspective here . . . from a guy who isn’t a very big dual air fork fan. This is perhaps the ONLY dual air fork I could see myself falling in love with.