<div class='quotetop'>QUOTE (Babelfish @ Jun 20 2008, 12:34 PM)
<{POST_SNAPBACK}><div class='quotemain'>Seems to me as if you are mixing two separate things here. The Rider/Bike Combo and only the bike. The bikes COG is allways the same (depending on reference you might say it changes slightly with suspension compression). The combo obviously move with the rider.
Sitting high on the bike rise the combo COG, but that doesn't make flicking the bike any harder as the momenteum increase as well. Besides, with a low COG of the bike the more influence the rider have so I still don't get what they gain.
I know you learned about leverage/torque at some point in your life. When I bike is leaned on it's side, the tires are the fulcrum of the lever. If you take an object of set mass (an engine) and move it farther from the fulcrum, greater leverage is generated. The extra leverage makes easy work when balancing a speeding bike at full lean. Unfortunately, all additional leverage obtained from moving the mass outward must be overcome when moving the bike from full lean back to vertical.
In other words, you need spirited steering (good for Nicky, not good for Dani) and a rider with enough mass to chuck the bike around (good for Nicky, not good for Dani).
<div class='quotetop'>QUOTE <div class='quotemain'>I'm not sure but you
may have a point that higher rider COG require less hanging off, but intuitivly I would guess it make no difference, but regardless, a larger rider need less movement relative to his size to achive the same change of COG.
Sorry if I was unclear. I was trying to say that moving the engine up towards the tank lets the bike do some of its own "hanging off". The rider can stay in farther in the saddle and get better feedback from both tires.
<div class='quotetop'>QUOTE <div class='quotemain'>This of course help connection to the bike. So far so good, but on the rest I got lost. Available grip and contact pathc size change over the tire profile but in general it's at it's smallest when the bike is upright, increasingly larger towards the edge. But I guess they try to optimize the profile for maximum patch before the edge as this is where both acceleration and braking are at it's most critical. If you say the larger riders aim for that sweetspot I agree, if you suggest the try to raise it above that, if possible right up, that would be .......... This is NOT dirt track and the way to get maximum grip is very different.
The contact patch size is important but what is most important is the work it is required to perform. The less a bike leans, the less torsional stress the tires undergo. Even when the contact patch is huge, if all the tire's grip is being used to manage torsional forces there is no grip left to handle acceleration.
When you have extra torque generated by a high center of gravity you can countersteer less and steer more. In other words you are keeping the bike vertical and limiting the tortional forces on the contact patch. When torsional forces are limited you have more grip to handle acceleration and braking.
Obviously, the above is way oversimplified and I wouldn't even know how such phenomenon's actually manifest themselves with today's tire technology. Nonetheless, such a phenomenon still exists.
High CG is not absolutely better, but, if you have a rider large enough to overcome it's shortcomings, moving the engine upward can only help the handling characteristics.
P.S. I have made one mistake when talking about high CG machines. I said corner entry is the difficult bit. That is incorrect, corner exit is the difficult bit. Getting the bike to full lean is easy picking it back up again is the hard part. Obviously, I was confronted with my mistake when Nicky talked about how hard difficult the RC212V is to get out of corners when equipped with the pneumatic engine.
I screwed up?!
