Im going to race in a duathalon(first one) this spring, the bike part is 16 miles.Is it worth the money for me to get a aero fork? I will be rideing a cannondale r900si.
An aero fork will make a difference of about 30 seconds over 40 kms according to Jim Martin, et al and other researchers. All aero forks are quite aero so you’re likely talking less than six or seven seconds or so from the latest gollygeewhiz $$$ model to any other.
I know that the Giant TCR aero fork tested very well and I’ve seen these on ebay quite cheap from time to time. If one of them or something similiar will fit your cannondale (it should)you don’t have to spend huge dollars.
Other low buck but big performance add ons - CH Aero disc covers for $59.95, a used front wheel such as Hed Jet 60, Campy Shamal ($100 or so). This combo will save a minute or so over regular wheels.
Be sure also to get appropriate aero bars for a road geometry bike. You’ll want them shorter such as Oval “big slam”, Profile Jammer GT or use small size tri bars such as small Syntace C2, etc.
Get fitted and setup in a comfortable aero position first.
Ride alot in aero position. Get an aero front wheel, then a rear wheel and lastly the aero fork. Good luck.
As Cerveloguy noted, the “free speed” you stand to gain from an aero fork over that distance is marginal. Other ways to gain even more speed with zero or minimal added expense would include:
-Working on your transitions, including using elastic laces or lace locks (I like Yankz).
-Working on achieving and maintaining a good aero body position.
-Cleaning and lubricating your drive train and hubs.
Have a great race!
An aero fork can be a disaster if you get the one with the wrong rake. Too much rake on a steeper head tube and you have problems, too little rake on a shallower head tube and you have huge problems. You can end up with the rubber side up during an evasive maneouver as the steering can be too quick for the intended steering geometry. It would be best to measure your fork rake and shop for forks that fit within the range.
That being said, I think the fork is the last thing you should change out. Work on your position, your wheels, and the really free aero changes (like flapping cables, etc.) before attacking the fork. I would even suggest an aero helmet before the aero fork, just my blunt opinion.
Dus are fun. If you are concerned about your transitions (with such a short bike leg, I would be), I would get some Pyro platforms; they are really quick. I would only use them in short races, though.