<div class='quotetop'>QUOTE (Babelfish @ Jun 21 2008, 01:42 AM)
<{POST_SNAPBACK}><div class='quotemain'>but there is another thing, you said the Yamaha had high COG? but the first of all, the fight for years has been to lower the cog. The tank you talk about is just a carbon cover for the airfilter, the tank is mainly under the seat. The IL has inherntly a lower COG than the V4. That's one of the few drawbacks witht the V4, it got lots of heavy rotating parts due to it's four cam shafts, and two setts of cam drive train, compared to the IL's 2 shafts and one dive train. Of course the COG might have raised a bit with the pnumatics but I'm not sure it changes it much at all. Heavy springs are just that, heavy. So my bet is that the Yamaha have a lower COG than the old spring valve Honda
I think you are right. Low COG bikes like to high side (in a TC world). Lorenzo has demonstrated that the M1 likes to highside. Likewise Pedrosa has proved the RC212V likes to high side as well. Both Lorenzo and Pedrosa have been masters of the mini-highside. The bike pitches them five feet in the air, the bike low-sides, and then Peders/Lorenzo belly flop on the pavement. I think the M1 is probably low CG.
High CG bikes tuck and lowside (in a TC world). Stoner and Pedrosa must have tucked the RC211V at least 50 times in all their test and practice sessions.
You're right the M1 has low CG;however, Yamaha and Honda (RC212V) prop the rider way up in the seat. It seems that they are using the seat position to counteract the low CG of the bike. So the move to Low CG was probably to centralize the CG of the bike rider combo while increasing the effect the rider has on handling.
<div class='quotetop'>QUOTE <div class='quotemain'>Now I'm lost again. No matter how COG influence the lean angle the tire has to cope with the same amount of forces. The bikes lean angle does not alone change that. As you said you increase leverage with higher COG, in that case it's proprtional with the coresponding increased lean angle from a lower COG, the tire has the exact same amount of forces to handle, only thing different is where on the tire the forces attac. Do we agree on that?
There is not any added or substracted forces involved for the tire no matter where the COG is.
The only thing the rider/design can influence is where on the tire these forces work.
Again, keeping the bike vertical does nothing for torsional forces (as long as we are talking about the same thing here, the sentripital force) The sentripetal force does not change, it's a function of speed, radius and mass and has nothing to do with COG of lean angle.
In a world with no yaw, what you've said is true. However, using less lean to make the same turn means the bike is controlling yaw effectively and making more efficient use of the work the tires supply. In theory, leaning the bike less does require less work.
If the tires are working less to make a turn, there is more work available for acceleration.
I will admit though, the efficient use of yaw is probably not nearly as important as the rider's feel. Riders are comfortable spinning the rear on a bike that is close to vertical. Most of them are not keen to risk spinning the rear wheel when the bike is at full lean. TC has changes things a lot though.