rec.autos.simulators

SBK: Wobble and weave...

Eric Cot

SBK: Wobble and weave...

by Eric Cot » Mon, 05 Apr 1999 05:00:00

While driving SBK Superbike, old stuff that i read, but never applied
on the road (was not into racing, apart a racing school) came to me as
a flash. Remember Cycle Guide (Honda guide as they called it), Cycle
and Motorcyclist ? These were my bibles, got something like 500 of them
that I bought from mid to late 80's, and they were talking about rake
and trail.
Which I understood, but when you're on a low budget, changing these
values
unless you have a machine shop, was impossible...

But I remember that, if you change the rake only, by going steeper
(going closer
to vertical). Apart changing how the bike will react to direction input,
and how
stable or not it will be at high speed, there's something important that
could be
done with it.

Let's say you're entering a corner, the bike dive, and you're going a
bit to fast
in that corner. If you apply brake in the front slightly, keeping what's
left of
traction, and the bike dive even more (let's call it positive reaction),
then I'm
almost certain that changing the rake angle will affect this behavior
More rake
(steeper) then it dives even more, much less it could actually do the
contrary.

By having the correct amount of rake, could have a neutral situation
where
when applying the brake slightly, the bike would stay on the same axis.

Am I right or wrong ? Just asking....

Eric

http://www.racesimcentral.net/

btw, I did a superb animation screenshot, a huge wheelie
at Assen without loosing it. As soon as my page is done
on SBK Superbike, i'll announce it here

Cheers

  webmaster.vcf
< 1K Download
Bj.O.r

SBK: Wobble and weave...

by Bj.O.r » Tue, 06 Apr 1999 04:00:00


Wrong.... Only bikes with "funny" front ends can mantain a neutral attitude
during braking. It's not a good thing though, the "dive" is neccesary for
feedback and shift of weight forward to increase grip to avoid lockups. Even
"funny" front end bikes (BMW, BimotaTesi, Yamaha GTS)have some dive built in
to mantain feel for what the front *** is doing.

Ordinary telescopic forks compress every time a force is exerted upon them,
such as braking, no matter what rake angle either due to weight shift or on
longforks (heaven forbid...) due to deceleration force.

There was a time in the mid 80's when "anti dive" was the major hype on any
japanese bike. Every marqe had their own hilarious letter combination, but
it was essentially a system that stiffened compression damping when the
front brake was applied... Not to be seen anymore.... It was, and is a flop,
they had to make the systems so ineffective to maintain the feel under
braking that by the time fork and damping technology improved ("cartridge"
forks) it was a no gain, total waste of tme and money..

/Bj.O.rn, '98 900SS Ducati


rec.autos.simulators is a usenet newsgroup formed in December, 1993. As this group was always unmoderated there may be some spam or off topic articles included. Some links do point back to racesimcentral.net as we could not validate the original address. Please report any pages that you believe warrant deletion from this archive (include the link in your email). RaceSimCentral.net is in no way responsible and does not endorse any of the content herein.