Recently saw Matt Simkins new aero brake design - kinda like the old Hooker TT brakes (which incidentally go for a very pretty penny on eBay). The big question is: Are they worth it?
According to Matts real world aero calcs (performed by Tom Anhalt, Google Wattage member), the Simkins brake had a CdA of 0.2125 vs the Cervelo brake mech of 0.2152, or a difference of 0.0027.
That's gotta be a pretty small difference... heading on over to analyticcycling.com:
250w, CdA 0.2152 = 11.62 m/s or 41.83 kmh (25.98 mph)
250w, CdA 0.2124 = 11.66 m/s or 41.97 kmh (26.07 mph)
So a difference of 0.04 m/s... thats 4 cm (about an inch and a half) further per second.
Over 40 km, that's 57:22 compared with 57:11, a scant 11 seconds saved for $335 USD or $30/sec.
Worth it? Might be if the race was a biggie, and the winning margin is less than that! Probably not if 10 seconds can be gained reasonably easily by some other means, like practicing a transition between swim and bike. For TT's only, there would be more merit as the podium is frequently exchanged on the basis of a few seconds here and there.
As an aside I actually sanity checked what a front brake assembly was worth in CdA terms; Cervelo front brake mech on and off the bike the CdA difference was 0.004 - roughly double the difference between the Simkins brake and the Cervelo brake. So the test results do seem to be reasonable.
You can check out Matt's site: www.simkinsdesigns.com