ras11 wrote:Dudes... are you joking!!! I'm all about pragmatic equipment.. but come on! Light rims/tires/etc.. make a huge difference!
Listen, micro-accelerations (those 1-5cm movements your frame/body makes during the pedal stroke) account for a massive amount of energy. To slow down and speed up a rotating mass to adjust for these micro-accelerations is a lot. There are two things one can do... one is make your pedal stroke and body position better, or you can reduce mass.
It's true that with every pedalstroke your bike accelerates a bit (especially when you're climbing, at hight speed you won't notice it anymore), and between the pedal strokes it slows down a bit.
If you have light rims, your bike will be easier to accelerate with each pedal stroke. But it will also decelerate between the pedal stroke.
Heavier rims will result in a more constant speed uphill: smaller acceleration when you pedal, but also smaller deceleration when you don't pedal.
So when your riding uphill at constant speed, weight is the only thing that counts for your speed.
With light rims the micro-accelerations and decelerations are bigger, so the bike will feel lighter and more lively.
By the way, the rotational speed af the cranks is sooo small compared to the rims speed that the influence of the mass of the pedal is almost neglectible.
A small calculation:
You're riding 39-23 at 20 kilometer per hour.
The orbital speed of your tire is 5,555 meter/second
Your pedaling frequency is 92 strokes/min
That's 1.545 rotations / second.
So the orbital speed of your pedal is 2 * 3,14159 * 0,175 * 1,545 = 1.69 meter second.
Adding 100 grams to the tire weight will increase rotational energy with 0.5 * 0,1 * 5,5555555^2 = 1.543 Joule.
Adding 100 grams to the pedal weight will increase rotational energy with only
0.5 * 0.1 * 1.69^2 = 0.1428 Joule.
So: rotational mass of the cranks has much less influence than rotational mass of the rims / tires.
If you ride at a higher gear, the influence of the cranks compared to the influence of the rims will be even much less.
So: swap your Keo's and buy Conti Supersonics