Originally Posted by maxepower
I'm not sure either but I can make an educated guess. Maybe for example, on a mountain bike you want top speed so then you switch to the smaller gears and you will go fast over time but it takes a lot of power to "spool up" so to speak.
But, when you switch to the taller gears it becomes very easy to pedal and therfore quick initial speed. So maybe on an RC car there is less effort involved on a motor to "spool up" using larger pullys so more bottom end speed and with a mod motor you can attain top speed faster. Does this make sense?
Kinda?
Then again, I could be completely wrong!
Completely wrong, what you're explaining is gear ratios...
What I was referring to is simply the amount of bending the belt have to undertake to get around the pulley. It's the major cause of drag/inefficiency in a belt driven drivetrain so the bigger the pulleys, the lower the bending and thus the better the efficiency.
This is up to a certain point because if you increase both pulleys diameter without changing the internal ratio, then you increase belt speed, and so the length of belt that has to bend for a similar distance crossed by the car increases aswell, which reduces the efficiency.
Technically speaking what i just explained isn't belt wrap, belt wrap is simply the amount of teeth in contact between the belt and the pulley.