This topic has bugged me for almost a decade now....
People in the industry and out of it have this notion of "X HP at the crank" and "Y HP at the wheel"
From a physics standpoint that is actually completely incorrect - Let me explain.
Lets say we have an engine in gear, clutch depressed at peak revs - why does the engine not continue to rev beyond the peak RPM?
Because the energy required by it to suck the air in and push the exhaust out has reached the amount of mechanical power that the combustion is producing.
Now what happens when you progressively add a load to the engine thats revving at peak?
Imagine you engage the transmission and use a CVT to engage more and more mechanical load on it - the engine slows down...
When the engine slows down from the peak RPM, it actually makes more usable power - because the several dozen HP required to make the engine rev to the last 200 RPM or so is now flowing out of the transmission.
Consider our very dear Iron Barrel Bullet 500 which makes a claimed 22 BHP at 5000 odd RPM - what it means is that at 5000 RPM, all the power in the combustion is just enough to keep the bike revved up there.
By definition, if there is a transmission load (including the friction of the gearbox, primary and secondary chain, tires, wind) it will never hit 5000 RPM
So the point is not that you have 22 BHP at the crank that is somehow getting reduced at the wheel - that could never be - the transmission is solid - there is no mechanical "slop" - its like a lever - if the engine is at a certain RPM, the wheel is at a certain RPM and the bike is at a certain speed.
What is actually happening is that the torque demand from the rest of the vehicle has slowed the engine RPM down to the point where it is able to maintain fixed revs but not rise higher.
This means that if your 22 HP @ 5000 RPM bike is only revving to 4200 RPM on the road, the actual power being delivered is what you read off the dyno chart for that RPM (say 16 HP)
The difference in power between the RPM you hit in top gear on the road and the the RPM you hit on an engine dyno doesn't actually mean anything - 6 HP of power is not being converted into heat by the transmission alone.
Rather, all 16 HP from the engine is being converted to aero drag and transmission heat (and gravitational energy if you ride uphill) leaving none for the engine to reach a higher RPM (and hence suck more fuel and make more power)
There is no separate "crank HP" and "wheel HP" - there is only "no load HP" and "on road HP" - You can always "boost" your so called "wheel HP" by making the bike more aerodynamic, and have less friction with a slicker tire, better chain or whatever.
I hope this made sense.