rpms and speed
It never ceases to amaze me the number of people that report changing to XYZ expensive oil and report that their bike idles smoother, runs quieter, and takes less rpm to go a given mph. At least the last thing, rpms at a given mph, is totally imagined.
Unless the new oil corrected a slipping clutch issue, it's IMPOSSIBLE!
Gear-inches is the technical term that describes the distance the bike moves per X number of revolutions of the engine. The ONLY FACTORS that affect Gear-inches are: Wheel/tire diameter, Rear Sprocket teeth, Countersprocket teeth, total Transmission ratio.
We have seven transmission selections in our bikes. 1-6 and neutral. Since 1-6 are FIXED, the Rear Sprocket and Countersprocket teeth are FIXED, and the Wheel diameter is FIXED, the only thing that can change the relationship between rpm and speed is the TIRE or CLUTCH slippage.
IF you assume the clutch isn't slipping, the chain is intact, and the tire isn't more or less inflated or running off-center (leaning), and the tire isn't slipping on the road (which it CAN do under hard acceleration or deceleration) it matters not if there is a headwind, tailwind, wide-open throttle or zero throttle:
RPMS in a given gear will always be equal at any given speed.
An exception is NEUTRAL...because, the 6 transmission fixed gearsets are taken out of the equation, and speed is then independent from rpms.
Weight doesn't matter. Power doesn't matter. Head- or Tail-winds don't matter. Relative speed doesn't matter (whether it's one mph or 100 mph)...one rpm will move the bike a certain number of inches in a given gear, as long as the clutch or tires aren't slipping, or you aren't leaning off-center of the tire, and the tire inflation/deflection is unchanged, and the chain is intact.
So, if you divide your rpm by minutes to get rpms/minute, you do the same to your inches per minute to get inches/minute...which we conveniently change to miles/hour or km/hour.