Belatti wrote:With the same kart he reached 17.100rpm in the straight and I reached 17.500rpm.
We were running a long ratio (10:78) in order to preserve the engine.
Tires have a 280mm diameter. You do the math to calculate top speed diference
Contributing to an ancient thread, but it wasn't me that resurrected it
For bicycle speed meters, which typically measure the number of wheel rotations, you have to measure the roll-out distance of the wheel (how far you travel per revolution) with yourself sat on the bike to get accurate speeds. If you calculate it using pi*d you will get a different (larger) answer to what you get if you roll the bike unloaded, and that in turn is larger than what you get if you roll the bike with yourself on it. This is because the compression around the contact patch reduces the effective radius of the wheel-tyre system, and that compression is larger the more load is on the tyre.
So Mr Heavy is even further disadvantaged than the numbers above indicate (unless he increases his tyre pressures) because the wheels are effectively smaller for him than for Belatti.
However: I used to be about 2% slower than my colleagues when I weighed 115kg to their ~80kg. So either I'm the second coming of Senna or there's more to it than this