You should be able to draw three conclusions from the data in table 1. One, changing out the standard wheels has the greatest effect on drag. Gios verse the Schwinn track bike. Two, the drag difference between the two aerodynamic frames is very small, but quite large in comparison of standard round tubes. Three, even with the rider you can still have a measurable difference in drag. Our point here is that the ZR would have the aerodynamic performance resembling the Lotus and Super bike 2 by similarity.
So how does the aerodynamic drag benefit the rider? Table 2 is a mathematical model of the effects reduced aerodynamic drag has as function of time saved at a given distance and speed, provided the power out put is constant. The time saved in some cases is the margins by which a race is won or lost.
Table 2 Time Saved Due to Reduced Aerodynamic Drag
|
Drag Reduction |
Time savings in seconds |
|||
|
1000 meters |
4000 meters |
40 kilometers |
||
|
Pounds |
Grams |
35.2 mph (56.7kph) |
31 mph (49.9 kph) |
30 mph (48.3 Kph) |
|
0.02 |
9 |
-0.06 sec. |
-0.28 sec. |
-3.0 sec. |
|
0.04 |
18 |
-0.11 sec. |
-0.56 sec. |
-6.0 sec. |
|
0.10 |
45 |
-0.26 sec. |
-1.26 sec. |
-13.0 sec. |
|
0.20 |
91 |
-0.53 sec. |
-2.52 sec. |
-25.0 sec. |
|
0.40 |
181 |
-1.06 sec. |
-5.06 sec. |
-51.0 sec. |
|
1.00 |
454 |
-2.71 sec. |
-13.04 sec. |
-131.0 sec. |
The aerodynamic advantage of wheels with fewer spokes is well understood. The next aerodynamic advancement is the frame. Upgrading the aerodynamics of your frame is not an aftermarket option. If you have a non-aerodynamic bike frame you are as optimized as you'll get without buying a new frame. Remember that in general 80% of your road races are just battling the wind, and if you’re a triathlete its 100%. So why even consider a traditional frame if you're in the market for a new frame.
The following equation is the energy equation for a bicycle.
E = KE + PE + ME
Total Energy = Kinetic Energy + Potential Energy + Mechanical Energy
KE = ½mV2
m = rider + bike mass
V = your speed
PE = mgh
g = gravity constant
h = height gained as you climb
ME = Mechanical Energy = sum of all Rotational energy + sum of Spring Energy
Rotational energy is the energy required to "spin" all rotating parts
Spring Energy is the energy lost due to lateral flex in the frame and wheels
ME = R+ S
R =
I = mr2
I = Moment of rotational inertia
m = mass of each component (wheels, cranks)
r = radius at which the body of rotation is moving
W = angular velocity
S = N½Ky2
N = number of cycles in a given linear distance X
K = Stiffness constant of the frame and wheels
y = the deflection
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