Aprilia Falco Drive Force Diagram Discussion

If this is the first drive force diagram you've seen, it may not mean much to you. It's a family of curves, one for each gear, plotted from minimum useable rpm to maximum useable rpm. The independent axis of the graph shows you what road speed you'll be doing over that range. The dependent axis shows you how much force is propelling your bike at the rear contact patch. Acceleration is directly dependent on this force, so the higher up the curve, the quicker you are accelerating (changing speed). The further to the right you are on the curve, the faster your speed.

Also plotted to the graph are two additional curves.

The "Ultimate Force" curve is a theoretical line. It shows what the drive force would be if the engine were operated at the single rpm where it made peak power, and that power were transmitted through an infinitely variable transmission (something like two conical shaped pulleys with a belt between them). This is the most force you can possibly hope for at any given roadspeed. Your goal would be to build a bike that had curves as close as possible to this line.
The "Wind resistance" curve is a curve I fit, increased with the square of road speed. It demonstrates how much force the wind pushing against you takes away from your net drive force. For each drive curve, you need to subtract the wind resistance force. You can not accelerate when the wind resistance is stronger than the force your bike is producing. A second resistance, rolling resistance (not shown), is approximately independent of speed. It is the force you need to push your bike slowly around the parking lot (once it's already moving). It is a small value and it's usually ignored.

Some things you can derive from the graph:

If the bike really isn't making useable power beyond the ends of the curves (<3000 rpm or >10,500 rpm), then in first gear you need to be slipping the clutch to be able to accelerate from below 16 mph.
The wind is going to make your terminal velocity around 160 mph. After this speed, wind resistance is producing more force than the bike can overcome. This bike, as geared now, won't pull to redline in sixth gear. That's "wasted range", but gearing it that was may be useful in making the other gears more driveable, or in fuel economy.
This is a wide ratio transmission (typical for twins), especially through 1-2-3. For maximum acceleration, you are going to want to take the bike to redline (maybe the 5th-6th shift could be a little earlier). In the lower three gears, when you are forced to upshift by the rev limiter, you are going to notice a significant drop in acceleration in the next gear (this is not a good racing transmission). In particular, first is very low, and you probably won't want to downshift into it unless you're smooth. It's a common misconception that you want to shift at maximum power, or maximum torque. You really would want to shift whenenver the next gear brings more drive force than the previous. With the possible exception of fifth gear near redline, this bike doesn't cross it's force curves.
The physics of the wheelie and of wheelspin are detailed, but a loose rule of thumb is that interesting things start to happen when the bike is putting down more force than the weight of the bike and rider. That's about 625 lbs for me. From the graph, it appears that the bike will wheelie quite happily anywhere in first, and is pretty safe to push once you shift to second.

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