can anyone explain to me the relationship between swingarm angle and how it affrct rear wheel traction under acceleration and in real world, symptoms of too much/ too little angle? TIA jb
Well considering there are close to 5K users and only 2 self proclaimed suspension gurus, I'd say you were only starting your wait...
Really complicated issue. (Which is my way of saying I don't really understand it.) Go to http://www.eurospares.com and sign up for the chassis design list, there are some amazingly knowledgable people on there who could answer.
sure jim you outta know more than me id imagine!! by the way im the hillbilly (as you called me) that went to get you wendy's for lunch at talladega the first time you were there you yankee jb
i would love too, however it was explained to me in Aramethic and there is no direct translation. If ya speak/read Aramethic I will gladly help.
DOH!! That could not have been me, I wouldn't put down the hillbillies that way! Thank you, you're a wonderful audience very much I believe the traction issue is directly related to center of gravity. The bike's center is the crank. IMO, lining up all the pertinent pieces of the bike (crank, axles, swingarm pivot) gives one optimum traction. The swingarm angle is related to this by lining up the axle, so you could theoretically draw a line through the axle, pivot, and crank. We jack them up to acquire steering capabilities, but going too far (steeper angle) results in spin. Let's call that positive angle. The converse also causes spin, i.e. negative angle is beyond our imaginary line. You also have to account for your linkage ratio, and spring weight to avoid spin and maximize traction. I believe these items assist in obtaining the correct angle when the throttle is applied. Make sense? Can I get fries with that?
My two cents... If you jack it up too far the swingarm pivot will be higher than the ends of the chain, therefore the chassis will lift rather than squat under acceleration. Extreme example but you get the idea, your desired wieght transfer diminishes. BTW I speak aramethmatic, we call it cipherin' down here in the woods.
how do you aleays manage to jack my threads? (you are a fine one to talk about shut up and ride beotch!!) thanks for the input guys and Jim, we dont like hillbillies down here, the proper term is we're more rednecks esquire!! jb
Re: My two cents... Man, you're about to open a can with that one. The propensity of the rear end of the bike to rise under acceleration is due to the fact that the pivot point of the swingarm is higher than the rear axle. Force applied to the frame through the upward angled swingarm by the rear wheel causes the lift. Any degree of anti-squat will generally cause the rear of the bike to rise on throttle roll-on, which counteracts the inertial weight shift to the rear, improving front end traction in the process. That's why you accelerate through a turn to keep the front end planted, and why the front tucks when drive in a turn is lost due to a missed shift, false neutral, etc.
Keith Code explains that in his book "Twist of the Wrist". That's why your throttle plays the biggest role in suspension. The rear wheel is spinning and in turn forcing upward and forward on its load (you and the bike). The rear wheel is doing the work(in scientific term), and the rest is simply a load consisting of weight trasfer and the force of the great volume of air that you and the bike are moving(resistance). The weight of the total load pushes down and back on the weakest point; this is where the pivot comes into play. The suspension supports the pivot(weak point). If the pivot were too low in reference to the rear wheel, it would simply collapse, causing the tire to rise too high placing a part of the load below its "working point". 1/4 mile racers extend the swingarm to get the load as close as possible to the collapsing point, thus directing the "work" of the rear wheel more forward than upward. This lowers the center of gravity. We cannot do this, because we need our bikes to handle first and then propel second. We need a perfect balance including higher gravity center(for better handling), traction and propulsion. Or something like that.
Yeah, I sure did. J. Garvin offered me a ride on his new SV. I am looking forward to the experience on a lightweight bike. Still love the 600's though.
