OzVMX Forum
Clubroom => Tech Talk => Topic started by: Tahitian_Red on June 03, 2012, 05:30:57 am
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I'm building a DT-1 for MX and rules do not allow the use of a Webco frame lowering kit (or any frame mods really). I have a question about weight bias and center of gravity. I have read that the Webco kit lowers the engine in the frame cradle 1 1/2" and changes the weight bias from 47/53 to 43/57.
If I were to take as much weight off as possible above and outboard (unsprung weight) of the engine and them place 5lbs of weight under the cradle, near the footpeg bar, could I come close to the same improvement of the Webco lowering kit?
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No opinions on this one?
Maybe it's just crazy thoughts, but it seems like it should be a benefit. The crankshaft mass would still be above the axle height, but reducing unsprung weight and increasing center mass should help considerable. No?
???
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fugging 5lbs!,duh, :P
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I'd just take as much weight as possible off... & leave it all off.
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Your unsprung weight is your wheels and some of your suspension mass. reducing that weight will help. But adding 5 lbs. of sprung weight isn't going to be a benefit that works better than riding it 5 lbs. lighter! If you can get the weight off, then do it but this isn't drag racing where you are running in a straight line on pavement with a fixed position CG so that a better weight bias will overcome the penalties of the additional weight. In some racing there is a minimum weight for the class of racing. There you can benefit from building close to the minimum and then positioning the mass for best effect. In MX or Dirt riding you can build to the lightest bike possible within the class rules and adjust "YOUR" mass to move the CG while riding. Tire size and gearing will help if you make it "too light" and seem to be getting less traction from less lbs./sq.inch of surface contact. Of course bigger tire will typically add more weight and a larger "gyro effect". Always a trade off somewhere!
Swiss
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Thanks Swiss!