Okay, here are my "novice" comments on wheelbase, etc. Maybe they'll be
worth something to someone...
Before I ever raced my bike I had the wheelbase lengthened (56.69" stock,
now plus six inches) with a six-inch extended swingarm -- good and stiff, to
handle the increased power from the engine. The bike was lowered about 3/4"
in the front forks and the rear suspension pulled down about the same with
an "adjustable" link (I'm at the middle stop of a three-stop link -- the
lowest left too little ground clearance back there). And, worth
mentioning -- each time before I race it I have it measured and reset on the
Computrack alignment machine at the shop, making sure everything is straight
and true.
Mine was the only extended bike (at least in the 1350-size classes). Larry
Forstall's Hayabusa, driven by Marc What-was-his-name, and my bike were the
only two over the 2 - his was stock length. Lots of 12R's competed.
As a virgin I can't offer comments distilled from zillions of runs over the
years -- but I was happy with the handling of the bike. I'm comfortable
stating that the long wheelbase helped me maintain my confidence when
wheelspin came to visit at 180++ speeds, making the back end wiggle
about --- but not so much that I wasn't confident. I just needed to keep
cool, keep my hand in the throttle and WAIT for the thing to find some more
traction and settle down. And anyway it gave the spectators more
roostertail to watch! as the rear wheel spun up and down. I've stated here
before that I did need to do some steering, and again I think that the
longer wheelbase - the concomitant reduced "twitchiness" that the stock
short wheelbase offers but the longer swingarm reduced - made it easier for
me to correct when I saw I wasn't going straight between the lines. I
wasn't afraid to "bend the wheel, Toivo -- there's a twist in the road up
ahead!" --- even though I'd never driven at speeds like that before.
For aerodynamical reasons coupled with my 6'4" frame (see new name for race
team: "Seldom Seen Slim Racing") I would sit near the front of the seat
while in lower gears (gotta keep the front wheel on the ground, you know)
but move to the rear (pillion) seat as I got up to fifth (outa 6) so I could
tuck in better. My eyes didn't move too far back, if at all, but my weight
did shift towards the rear. Could that be another source of the stability I
enjoyed?
After World of Speed but before Maxton I had a new aero tail section put on
the bike. It is not only better shaped, but allows me about six inches or
so of "extra" seating. That means I can sit up front, as before, when I
need to, but have a real seat with a real butt-stop to hold my hiney in
place when I assume the extreme tuck. 189 and change at Maxton, so we'll
have to wait 'til next year at the Salt for more results.
I've got other stuff coming for 2002, so results may not be directly
comparable (nod here to DrMayf and his wonderful need for data, real data!).
We'll be adding some aero work after the driver's seat (staying in class,
though), and doing some front-end aero mods, too, and closing up some of the
holes in the front-and-middle parts of the fairing. Add a whole bunch of
new horsepower (isn't that what racers always ask for??) and I think the
bike'll be the snappy performer after which I lust.
Is that enough for now?
Jon #436 1350 M/PS/G
Marquette, Michigan
(that's way up north)
-----Original Message-----
Behalf Of landspeedracer
What is the effect of wheelbase on vehicle speed. Another words are long
wheelbase cars
<<<BIKES?>>>
inherently more stable than short ones? What are the advantages
or disadvantages?
John Beckett
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