Wheels and Aerodynamics
The maximum speed one can reach on a bicycle depends on two factors.
* One; the amount of power the rider can generate.
* Two; the amount of resistance generated by aerodynamic drag (90%) combined with the resistance of moving the mass of the bike and rider (10%).
Obviously the aerodynamic resistance (drag) plays a much greater role (excluding climbing).
The faster you ride, the more drag you create, therefore you have to produce more power exponentially just to maintain speed. Using this power to it's fullest potential requires efficiency. Since 90% of the resistance is drag the largest area to improve efficiency in cycling is aerodynamics. With all the "aero" wheels out there knowing which ones you should buy can be difficult. So we've put together a reference source for aero wheels.
For a pair of aero wheels to be effective the rider must be traveling at least 14mph. However once these speeds are reached slower riders gain the most from aerodynamic wheels as they will travel longer (in time) through the air over a course that is the same length.
The front wheel is more important than the rear wheel as it is the one that breaks the air first.
If a pair of aero wheels are heavier than your current wheels it does not mean they will be slower. As we stated above aerodynamics comprises 90% of the resistance while cycling. Therefore the extra weight should be insignificant when compared to the aerodynamic savings. For specific information see; How Important is Aerodynamics Vs. Weight?
Approximate time savings are:
40K Savings Ironman Savings
Front
Xlab / Hed Alps / Zipp 404 64s 4m 48s
3 spoke / Zipp 808 82s 6m 9s
Rear
Xlab / Hed Alps / Zipp 404 38s 2m 51s
3 spoke / Zipp 808 49s 3m 40s
Disk 58s 4m 21s