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Motorcycle Physics Question

Posted: Fri Nov 25, 2005 12:25 pm
by bikerdudeQC
We spend a lot of time talking about mods that will shave a pound or two off the weight of the bike. I've always wondered if, from a performance standpoint, there was a difference between taking pounds of the rider or the bike. Anyone know the answer?

thx

Posted: Fri Nov 25, 2005 3:33 pm
by JToole
Of course. Lightening the rider allows easier attraction of riders of the opposite sex! :lol:

Seriously, yes. Changing the rider's weight will affect the optimal suspension set-up. That means the setup should chnge with the rider's weight to keep optimal handling.

On heavier bikes with a high CG, riders who use their weight to steer will find weight shifts less effective. Using countersteer will nearly completely negate that effect.

Posted: Fri Nov 25, 2005 3:38 pm
by bikerdudeQC
Hadn't thought of the steering aspect. interesting.

Posted: Fri Nov 25, 2005 4:47 pm
by NoRRmad
Since the rider sits on top of the bike, reducing his weight will lower the center of gravity, so there will be a little less tendency to wheelie, but in terms of zero-to-sixty time, mass is mass, no matter where it's located.

Posted: Fri Nov 25, 2005 4:49 pm
by BobFV1
Changing the sprung weight, like the riders pot belly, will affect performance, but if you are looking for more bang for your buck, look at unsprung weight, like wheels.

The principle applies more to a sport bike from a practical perspective, as a heavier touring bike really should have some stout wheels on it.

I think people with a lower body mass index live longer, so that might be something to consider...

Posted: Fri Nov 25, 2005 10:24 pm
by CycleRob
When my shop raced a 600 SportBike in CCS racing, we reached a point where every ounce was removed from the bike and every tenth horsepower was added to to both raise and flatten the powerpeak. Then our only rider, Larry, put himself on a fittness diet. In the bike's weight range, every 6 pounds equals one horsepower. Not only that, that weight loss helps bigtime when on the brakes and in the corners.

At 5'6" and 147lbs (167.64cm, 66.67kg) I ride a high performance 1150R - - - even though it's almost stock. I recommend you loose that unhealthy weight and seriously think about NOT chewing yourself into the ground.

--Rob--

Posted: Fri Nov 25, 2005 10:40 pm
by Guest
bikerdudeQC,

I have posted on the subject matter on several ocassions, and it works to about 4 HP equivalent for ebery 23 pounds removed.

Since I paid $249 nfor an R259 (Techlusion) and it added 4 HP to the bottom line it is a no brainer that losing weight is both healthy, inexpensive and will add performance to your bike.

Let's see a loss of 125 pounds would be the equivalent of 20 HP.....GREAT!!!! :roll: :roll:

Posted: Fri Nov 25, 2005 10:42 pm
by boxermania
Yep, the post above is mine......Grrrr