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The Cannondale Six System
 
By Staff
Date: 3/6/2007
The Cannondale Six System
 

The DP investigates the experimental aspects of Cannondale's System Six with Cannondale's Team Liaison and Project Engineer, Curt Davis.

By Alicia Hopkins

Mauro Da Dalto's System Six

You have said that front-end stiffness was the most important feature of the System Six, but you have also made massive improvements on the bottom bracket as well. What is the end result on torque improvement?

By concentrating on the whole bike as a system, the rider benefits in every way. The most important tube on a frame is the downtube, the System Six uses a 58mm diameter downtube on the 56cm and up and a 54mm diameter downtube on the 54cm and smaller frame sizes. The downtube shares the force applied to the pedals as it sees this in a torsional load, and this is the same load it encounters in a sprinting situation, or when a climber stands up and accelerates. The oversize double butted Aluminum chainstays have been responsible for much of our Cannondale feel over the years and this is true on this frame as well. The big gains in bottom bracket stiffness are the result of the chainstays, downtube and SI Hollowgram's 30mm oversized AL. Bottom bracket spindle working together!

The System Six utilizes unidirectional carbon fiber for the chassis, have you done any experimentation with other materials such as carbon nanotubes? Aluminum alloys are also used; how familiar are you with amorphous alloys, and has that direction been discussed? How is the Aluminum fused to the carbon sections?

Unidirectional carbon allows us infinite flexibility in achieving specific ride properties for frames also, by not using a decorative weave we can save weight while achieving a unique look. At this point nanotechnology is in the early stages, and it can't be applied to frame technology to cost effectively achieve strengths or properties that a medium to high modulus carbon has right now. We use 6000 series aluminum, heat treated to T6 and the carbon is co-molded in a press while being bladder molded to the Aluminum rear. The Carbon front triangle is not made ahead of time, it is laid up and by co-molding it to the Aluminum there are no glues to add weight or increase variability in our process.

The System Six was compared to similar bikes made by Scott, Specialized, etc. Why were there no comparisons to manufacturers such as Look or Ridley?

We test every high level, recognized competitor's frame in our test lab. We perform non-destructive and destructive tests ascertaining deflections, and load numbers to failure. I think we choose certain companies to compare them to because of the public's familiarity with these brands.

How long has Cannondale been involved in crank development, and was this just a natural evolution following the improvements on the bottom bracket? How did the prototype ridden by Charly at the Tour of California perform?

We have been developing cranks for 10+ years, starting with the Magic motorcycle crank, then the successful 900 outboard bearing style , this used the familiar AL splined crank arm interface ridden for years by Saeco and Volvo Cannondale MTB'ers, to the recent, Si Hollowgram Al integrated cranks ridden since 2000 by all of our pro teams to many victories trouble free. The Super light cranks Charlie used are about 45 grams lighter (just arms per pair) then the current Al SI HOLLOWGRAM and performed flawlessly, just a note, we had tested them in the lab first to insure Charlie's safety!!! We try to get team riders on our equipment as soon as possible, but we always consider their safety.

Pellizotti at the start of Stage 6
Photo courtesy of Will Swetnam of Rideventura.com

How many years has the System Six been in development, and which suggestions from the teams and riders were the most useful?

The System Six was a multi year project, starting shortly after the first 6_13 then running concurrently until it reached production. The team's liked the 6_13 but wanted a frame that was more "scatante" a frame that had more stiffness in the front end a crisp feel when accelerating. I should mention that I have yet to meet a pro rider that has ridden a frame with too much lateral stiffness, with what these guys do (high speed descending, cornering, sprinting, climbing) their needs can differ form the needs of a domestic amateur racer or enthusiast. The System Six frame stiffness requirements were derived from feedback from team Saeco and Lampre riders. Diluca was one of the riders who we worked with to obtain our design goals. The feedback provided led us to use larger tubes....and thus a super large headtube downtube/ toptube cluster. The front end stiffness was of the utmost importance on this frame as well as high speed confidence and stability. This large head tube gave us the room to improve fork stiffness, our all carbon forks (even dropouts) uses a 1 1/2" steerer for the bottom 3 inches that tapers to a standard 1 1/8" steerer allowing the uses of an off the shelf stem. This oversize tube junction coupled with the proper lay up of unidirectional carbon fiber makes for a super stable, stiff, and efficient frame. The shape of the toptube give the frame some road bump compliance and the shape and thin walls of the Al rear end also offer the rider compliance.


How much research and development has Cannondale been engaged in concerning time trial bikes, and have you been to the wind tunnel?

We have our aero frame (6_13 slice) which has been tested in several ways. In the wind tunnel (LSWT San Diego) Jan 2006 with Nathan O'Neill and Faris Al Sultan (Faris won Ironman Hawaii 2005 on the Al only version). The testing was very informative especially with the help of Nathan as he has been in the tunnel several times before and really understands how to test. He is meticulous with his bike set up and trains very specifically with an SRM so he knows what wattage to test at, and what wattage he TT's at and he has all of his previous tunnel records so we had some tests to compare against. Faris has tested in the wind tunnel but has also conducted many tests on the track in Cologne Germany with Ulrich Schoberer (SRM founder) we were also able to compare Faris' tests to other frames he had ridden in his career, some Cannondale, some not. We use this information in the decision on geometry (very large percentage of importance to rider) and with tweaking tube shapes. We use a 75 degree seat tube angle frame with a seat post that can effectively slacken or steepen the ST Angle , this will allow a UCI governed athlete to compete successfully or a triathlete to maximize his off the bike running efficiency. Each time we go to the tunnel we are able to see improvements and quantify them.

I know that you use Finite Element Analysis for vibration and fatigue analysis. Have you simulated the brutality of Paris-Roubaix, and how does the bike compare to others who usually ride steel for the race?

We feel as though our in house testing lab gives us great piece of mind when our pro riders hurl themselves over the cobbles of Northern Europe. I can't say that we have looked at the course of Paris Roubaix specifically, but we believe that our full carbon Synapse frame, with tube shapes that allow for some vertical compliance should leave the riders no excuses!

Other than the possible implementation of nanotechnology, what other technological advances would Cannondale envision implementing into the development and further adaptation/improvement of the System Six?

We will continue to evolve our flagship road racing frame, as we did from the 6_13 to the system 6. We will be looking to reduce the weight while keeping an overall system stiffness that our Healthnet and Liquigas riders have come to expect. I would imagine we'll have to use more material with a lower molecular weight to achieve this wherever we can.

Kjell Calström' s System Six awaits the start of Stage 3 at the Amgen Tour of California

Photo courtesy of Brian Dallas at www. rideventura.com

Cannondale offers the System Six in 8 sizes, and the three teams Cannondale sponsors, Health Net, Barloworld, and Liquigas all ride stock frames.

 
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