juliend wrote:Yep yep. As far as i know, 194lbs is still the minimum for a 2 stroke running in the 250 class, right?
So again, how is the supposed "weight savings" from an aluminum frame any sort of benefit? pure marketing.
I'm not scoffing at the ally frame, many people love them. There are some benefits there. I'm just pointing out that weight savings is not one of them. The steel frame can be made just as light if not lighter. Have a peek at a KTM, lately?
I have seen KTM's, very nice bikes, and very light. Steel frames? Yes. But why an alloy subframe? If as you claim , they could make one just as light, cheaper and just as strong from steel? Hmmm? Steel shortage in Austria? Not that i'm aware of. Because they can't make it as strong and just as light from steel? No way you say? So it must be more marketing hype, right?
How about this? A small part of an article, but the concept has been around and evolving for years.--mass centralization
A motorcycle in motion moves in roll, yaw and pitch. Bank into a corner and the bike rolls around a roughly horizontal axis oriented from front to rear. In the corner the bike yaws, rotating left or right around a vertical axis. As the bike accelerates or decelerates there's movement in pitch around a horizontal, lateral axis. Pitch doesn't directly affect the direction of travel, but it's got to be controlled-think of the downsides of an uncontrolled wheelie.
The closer the weight is concentrated around these axes, the easier it is to rotate the motorcycle around them. In a counter-example, a man walking a high wire between two skyscrapers doesn't want to rotate around his roll axis-he doesn't want to lean too far left or right. To help slow his rotation, he carries a horizontal pole that provides a mass (on each side) that's relatively distant from his roll axis. The pole makes it easier for him to balance because it makes it harder for him to rotate around his roll axis.
As we move the mass of the motorcycle along these axes, we are moving toward the center of mass in each direction. CAD makes it relatively easy for designers to know the effect of their efforts at mass centralization, as the weight and weight distribution of each part and each assembly can be calculated by the computer.
Single-shock rear suspensions, with the damper mounted just aft of the swingarm pivot, have been an important element in mass centralization. The old dual-shock suspensions not only had the dampers and springs mounted far to the rear, but the weight of those components was far from the motorcycle's centerline. Another significant improvement in mass centralization results from putting the fuel tank behind the airbox, moving a heavy object rearward and a light object forward. The vertical stacking of transmission shafts in new engine designs is an effective mass-centralizer, moving the crankshaft rearward relative to the transmission
Now, before this is dismissed as a "marketing ploy", witch craft, or hooey. Let's exaggerate to the extreme for just a moment to prove the point. Why don't the factories mount the engine on top of the front fender? It would be out in the airflow, thus eliminating the need for a cooling system and saving weight, maintaining it would be easier, good carb access and all, and they could even gain power through the ram air available! Makes sense so why don't they do it? Because the bike would handle like crap, thats why.
KTM saw eliminating the linkage as a way to save weight and it was. But they ran into the same problems that ATK (another small company) ran into with their linkless suspension, getting consistent, smooth suspension action. Luckily having to go back to a link type system won't hurt them that much because the extra weight will be very close to the bikes center of gravity. Again....mass centralization at work.
Now, can you or I feel the difference in the new hondasaki from last year because they shaved 110 grams from their handlebar weight and moved the engine 5mm rearward? Heck no. But you can bet your butt that they've tried it out on their computer programs and then tested it with a McGrath, Carmichael, or Stewart and found out it worked or they wouldn't have done it. It may take a few years to fine tune the ideas,and for sure it's not cheap, but once the bigger companies spend the huge development money and prove that their "marketing ploys" work, eventually the smaller companies either copy them (alloy subframes for example) or fade away.
My father in law, after riding a "new" 87 yamaha of mine complained that, "the front end is too light it doesn't stick to the ground like my old Bultaco did!" My reply? "Well old man get your fat arse off the seat, stand up and PUT some weight on the front, then it'll stick better then your old Bultaco!"
Again.......... mass centralization at work. Just saying. Time marches on and we can't stop it.
And Julliend don't take offense, i like jousting with you
