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Friday, August 8, 2008

8 2 2008 Pro Lite with Hed disk and Aerospoke

Wheel weights with tubes, tires and cogs:

-Hed clincher disk - 3.15 lbs = 1,429 grams

-Aerospoke front clincher five spoke - 4.11 lbs = 1,864 grams

-Zipp 404 front tubular - 2.04 lbs = 925 grams

-Zipp 404 rear tubular - 2.09 lbs = 948 grams

-Mavic ellipse front clincher - 2.14 lbs = 971 grams

-Mavic ellipse rear clincher - 3.06 lbs = 1,388 grams

-American classic front clincher - 2.05 lbs = 930 grams

-Hed tri spoke rear clincher - 3.04 lbs = 1,379 grams

-Specialized tri spoke front tubular - 2.10 lbs = 953 grams

Based on some research and reading this is what I gathered:

Newton second law of motion is Force = Mass x Acceleration (F=ma). The variables which affect the propulsion of a bicycle are:

-Aerodynamic drag resulting from - rider, frame, front wheel, rear wheel

-Inertial forces - bike and rider mass, front and rear wheel mass and its distribution (wheel inertia)

-Rolling resistance - total system mass, tire pressure and width

-Gravitational forces - bike and rider mass, front and rear wheel mass

-Miscellaneous - drive train losses, component flex

Wheels account for almost 10% of the total power required to race your bike and the dominant factor in wheel performance is aerodynamics. Wheel mass is a second order effect (nearly 10 times less significant) and wheel inertia is a third order effect (nearly 100 times less significant). The best wheels in terms of performance are the ones that are lightweight, aerodynamic and are strong enough to get you to the finish line. The problem with these high performance wheels, though, is that they sacrifice on the other two key variables important in wheel selection: durability and price. High performance wheels are neither durable nor cheap.

In summary the rider pushing the pedals matters most, so swapping out your wheels may not make you the next Eddy Merckx. They may, however, help out a bit in the next race.

So the dilemma is choosing the right combination of wheels to ride a fast kilo and 200 meter time trial.

Not withstanding I am leaning towards the super heavy and aerodynamic configuration above with the Hed disk in the back and Aerospoke in the front for the Kilo. Although the heavier wheels would initially take more force to accelerate the flywheel effect (inertia) should kick in once they are up to speed.

1 comment:

barca96 said...

Nice bike you got there.
Do you still have it?
I have a question though, why did you buy a bike with a single speed/gear?
Isn't that harder to go around with?