I wanted to go a bit further on this... because it was really, really one of the concepts I had trouble with.
The main reasons why weight distro and contact patches are so misunderstood is because your average street rider doesn't really have a clue what is truly meant by "
steer with the rear". Its like some sort of voodoo and beyond some sort of bike magic that only the motogp pros are privy to.
To explain this concept in simple terms, forget motorcycles for a moment and focus on momentum and a pivot point. If momentum is moving a point around another point then the direction is constantly changing. If you can control or affect the momentum of the moving point you can change the direction. Now... let's apply that to bikes.
Let's say your front wheel is the pivot point and the rear wheel rotates around it. You can see this vividly when a rider does a circle burnout. How did he change direction? Did he steer with the rear? Did the the rear pivot around the front? Next, let's watch some semi pro and pro racers come down the back straight at 175mph and start to brake for the turn at the end. Some riders can kick out the rear prior to the turn in point, it's informally known as a "backing it in".
When that rider reaches his turn point, he countersteers to a very minimum to what angle the bike is already at. Because the front and rear wheel are no longer in line with each other. Did that rider steer with the rear? Did the rear pivot around the front? Or how about this... A rider is very aggressive with the throttle mid corner and the rear slides out. Did it pivot around the front? Is the bike pointed in the same direction? How about if the rear slides and the rider chops the throttle, why does that result in a highside so often? Because when the rear regains traction, the bike wants to change direction so quickly it ejects the rider.
Lastly, during stunt shows, riders may do circle wheelies. aka, turning their bikes into unicycles. The physics here are different but the fact remains that they can control the rear via the throttle to maintain or change direction.
Now what does all this have to do with contact patches!?!??!
Mr. Fist will be the first to tell you a lot. A very slow throttle roll doesn't weight the rear enough, the front contact patch is spread too large and will want to turn the bike further into the corner. Alternatively, if the rider is very heavy handed, the front's patch is too small and the bike will want to run wide in the corner. Now think about that for a moment... If turning with the bars is already done, what are you steering with?
This is why only the riders who fully understand this will say "practice your roll off as much as your roll on."
More...
When doing a circle burnout, you need 100% contact and traction on the front and less in the rear. The smaller contact patch will hold the bike as there is no cornering load in effect and you want enough patch in the rear to make a lot of smoke.
When riding a liter bike exiting turn 10 at 105 mph while lofting the front in the air, the rear patch handles near 90-100% of the load as lean angle decreases and throttle is applied. It works because cornering forces decrease as lean angle decreases. Drifting is another example of pivoting that is in between a circle burnout and unicycle, but yet... still a very good example of steering with the rear. Too much gas sends the car in a spinout, too little and the car snaps back inline changing the direction quickly just like a bike.
For us normal riders, we should strive for a nice 40/60 (front/rear) via a smooth 5th gear roll on. That would be 3rd or 4th gear for us 250 riders
depending on your gearing and setup. This keeps both wheels on the tarmac and takes advantage of the bikes strengths while minimizing the exposure to its weaknesses.