Re: Harley Davidson Dyna ride height

My recollection is that ALL frames flexed as tyres got stickier and stickier.
Steel frames became in effect springs and would contribute some gawd-awful
headshake and other movement whilst alumnum has more more inherent dampning.

 

Yes, but the problem wasn't that the super-rigid frames made for worse
handling, because ultimately, you want the most rigid chassis possible
in order to stop the wheels wandering around.

The real problem was that the frames were *so* stiff that the riders
were getting little or no feedback: nothing to tell them they were
approaching the point of no return. And they were crashing as a result.

Chassis builders now build a certain amount of flex into some race
chassis as a means of providing 'feel'.

I remember having one of my almighty arguments with the late lamented
Hoyt McKagen about this. he utterly refused to believe chassis builders
did this. Then he went to some chassis web forum, and none other than
Tony Foale told him they did )

As you say, or rather imply, as tyres get stickier they transmit more
loads to the chassis which flexes more as a result. It's not really a
matter of steel being better than ally - although ally is obviously
lighter, in some applications. I mean, Ducati has done rather well with
a basic steel frame....

 

Still bollocks....

 

You still haven't told us what you ride. Sounds like your wife wears
the racing leathers in your family.

Maybe you should let your wife take over so we can get some firsthand
info for a change from someone truly in the know.

Must've been the "special FUSA Olympics" or something. Never seen a TZ
pull a lead on a field of latemodel literbikes.

Ah, so now anyone over 150# is not an effective rider? What are we of
ample mass to do then?

Or is throwing a leg over a 170horse beast now considered "cheating"
cause it isn't a tiddler?

Good luck keeping your 2 on the pipe during a particularly tight
hairpin. Or during a looooooooooooong straight where horsepower rules
the day.

 

The cam drive, camshafts, valves, valve guides, valve seals, valve
springs, collets, and shims on a GSXR do NOT weigh 85 pounds, so we
would NOT have 300-lb 2-stroke GSXRs, any more than we have 315-lb
4-stroke GSXRs today.

You keep on whining about the weight and CG of 4-strokes vs 2-strokes
when the fact of the matter is that today (as opposed to 30 years ago)
those differences are negligible when compared to the power production
differences, power delivery differences, and engine braking
characteristic differences.

And you keep referring to some mythical race you saw pitting open class
dinosaur 4-strokes against equally antique 2-smoke 250s, when anyone
how goes to any local racetrack with a stopwatch today will see that
rider skill makes far more difference in lap times between a current
state of the art 600cc inline four cylinder four stroke hyperbike and
an RS or TZ250 GP bike than the differences between the two motorcycles
make.

 

Yes, but the problem wasn't that the super-rigid frames made for worse
handling, because ultimately, you want the most rigid chassis possible
in order to stop the wheels wandering around.

The real problem was that the frames were *so* stiff that the riders
were getting little or no feedback: nothing to tell them they were
approaching the point of no return. And they were crashing as a result.

Chassis builders now build a certain amount of flex into some race
chassis as a means of providing 'feel'.[/QUOTE]

It's also because suspension only works in the vertical or near
vertical plane. When the bike is right over on it's ear, you rely on
the frame flexing to provide a certain amount of "suspension" and keep
the wheels in contact with the group.

If the frame is too stiff, you lose that and the bike becomes
skittish.

 

Not enough space here. Current rides include H-D, Suzi (Intruder), Triumph (79)
and Royal Enfield. Recently sold a 1200 Kwaker. Shall I start with the CB305s I
used to but 350 kits into or with the BSAs I had before that then work thru the
dozens of H-Ds and jap bikes or just stick with the limeys?

Absolutely! She's filled a wall with trophies and plaques. Was WERA regional
novice champ getting her expert plate in her 1st part-season. Was in the top 5
at WERA's GNFs 5 years in a row, 3rd one year and 8th in the 250GP class on a
125! You?

You'd really cry if I did that!

That's because you have never seen a race where they were allowed to compete
together. The big four jap manufacturers control AMA. They race to convince
suckers to buy their bikes just like the automakers used to sponsor NASCAR
teams. Their nightmare is that a TZ or the like would get into one of their race
comercials.

Teach your girl friend to ride and learn something about why a bike does/don't
handle then use that to help her win. With her lower CG (weight in hips and
bootie) she's better built for it anyway.

I built a 125 for a skinny kid to run in AMF races. Two MDs ordered factory
bikes. If they held together he'd be 3rd. One day they both DNFd. All he had
to do was ride sensibly for 2 more laps to win. Then I noticed this idiot
signaling him to go faster ... and risk crashing. He said he almost did crash
when he saw me punching the idiots lights out! If you're big, do what big does
best and leave mc roadracing to shrimps.

No, just kidding yourself. Current GP bikes make more than 170HP but the dudes
winning on them are still all little guys. Maybe we otta make them carry an
extra handicap weight like they do in horse racing.

No problemo .. and I'm not even a very good rider. I used to really enjoy
taking my RZ350 thru the twisties cuz it was easy to ride 100% - like with the
tires both sliding. But I had no illusions about winning any races given a 100+
pound weight penalty.

Thats why the 2-wheel NASCAR crowd prefers NASCAR tracks like Daytona. Banked
turns are just like straights. Only skill needed is to twist the throttle.

 

True on both counts. In the latter case the frame acts like a spring, twisting
to keep the tyres down. But springs need to be dampted. Steering dampners do
some of this. Aluminum I'm told has better internal (molecular) dampning than
steel. Ducati had done well with steel. OTOH when we began getting aluminum
frames for TZ250Ds from Bimey the riders loved them and Yamaha quickly adopted
them.

 

How much does the head assy from a GSXR weigh? The head from a 750 2-stroke
weighs under 10#.

Rider skill does indeed make the most difference at any local (club) race and I
would certainly hope that 600cc 4's are or someday will be as fast as a 250 2
stroke in mediocre hands. I checked several WERA races at Summit Point and guess
what - the top 3 in the slowest class (old RD350s) would have finished better
than mid-pack in A stuperbike! So obviously watching local club races isn't a
very good way to determing what bikes are best. I suggest you broaden your
horizon and put your watch first on the *winners* in Euro 250GP then on the
Stuperbike winners on the same tracks. I suspect you'll find that enlightening.
Any of y'all UK dudes have the numbers???

 

You have enough space to wax endless. But not a single listing of what
you currently own.

That's ok. Now tell me, from which sportbikes (that you've actually
ridden) have you culled the opinions you espouse?

Hahaha. I've seen club racing where they have the big boys and the
tiddlers out on the same track. By the time the tiddlers get up on
pipe the literbikes are a lap ahead!

Ah, so men should throw in the towel cause there's nothing to beat a
ladybird riding a TZ!

 

Are you familiar with the fact that when raced (yes, they did use the
engine for racing) the first thing the tuners did was throw away the
lube system and run them on pre-mix because the lube system was
inefficient and the pump was worth nothing more than added weight?

 

Please explain how a steering damper can possibly damp suspension
springs......

'Cos they don't.

 

Nooo.. It's funnier than that! He thinks they help stop the frame
twisting.....

Of course that's all in the name, eh? Steering 'dampner' = something for
stopping the frame flexing too fast! Obvious, innit? If you're a twat.

Dave

 

Of course not.

When a bike is heeled way over - almost horizontal on modern tyres - and a tire
hits a bump the force tends to twist the frame rather than be absorbed by the
suspension (vectors and all y'know). If the frame is too stiff the whole bike
becomes "unsprung weight" in effect and the force bounces the tire, causing
momentary traction losses that a rider may feel as "chatter" vs a smooth
controlable slide or drift. A good frame - by purpose or accident - has
"spring" to it which mitigates this ... the frame twists then rebounds like a
suspension spring does to keep the tyre down on the pavement. But unless this
springiness is damped it can cause all kinds of problems of its own, including
"tank slappers". This is the 'spring' I was refering too and is damped by what
we commonly call steering dampers. "Frame dampers" might be a better name but
??.

 

I provided a complete one but you snipped it.

Recently? GPZ600R, GSXR 750 and Hyabusa, but that's irrelevent. Riding a given
bike is a p-poor way to decide much, especially if you weigh 250#. Lap times
don't even tell the whole story. Honda's then-new Intercepter was faster and
handled far better than Kaw's iron-framed UJM (yes I owned both at different
times) but Lawson won the championship on a Kaw because the Hondas were
*treacherous* - like current UJM sporters.

And BTW, I'm not espousing opinion on the subject, I'm quoting scientific fact.
Get out your physics book and read the part about pendulums.

Yup. Happens at most club races. Literbikes outdrag the fast bikes down to the
first corner then wallow and plow around so dangerously that the equally
unskilled 'tiddler' riders are rightly afraid to get near them. That's why most
spectators think literbikes are fastest - and why poor riders prefer them.

Happened in the F-USA race I quote too, except the TZ rider was unintimidated.
He was about 10th going into turn one but passed the leaders by the top of the
hill and was crossing start/finish before they got half way around turn 9 - a
good 200 yard lead on the first lap. Goes to show .....

Are you saying that Kenny Roberts, the present champ, and all the other shrimps
are less than men??
What I said is that BIG guys have no more place on a racebike than little dudes
have in pro football or short dudes do in pro basketball. This doesn't say that
one can't go have fun testing your skill (I did), just don't expect to beat
shrimps or ladies who're just as good, or to impress anybody. And don't expect
a bike designed for them to handle right with your lard on it. I could finish
mid-pack or a little better riding the wheels off a bike my 125# buddy could win
on, but that didn't impress me or anybody else NOR does it indicate how well I
could ride let alone what I might know about bikes.

Dan Blocker (Hoss Cartright on screen) loved Lotus race cars but he didn't try
to drive them - he just gave smaller men the opportunity. Irv Kanamoto made a
couple men world champs but didn't win any GPs himself. I was never in their
league, but I try. I had a lot of fun exploring the universe at 6 cuz I could
imaging that ms Smith's front stoop was a rocket ship. You wanna believe your
400# UJM handles like a TZ be my guest.

 

Bwaahaahaahaa!

You really don't have a fucking clue, do you?

--
_______
..'_/_|_\_'. Ace (brucedotrogers a.t rochedotcom)
\`\ | /`/ GSX-R1000K3
`\\ | //' BOTAFOT#3, SbS#2, UKRMMA#13, DFV#8, SKA#2
`\|/`
`

 

Yes. Very different applications. We used to remove electric starter motors
and big batteries too. Does that mean electric start is worth nothing more than
added weight? Unlike touring riders, racers are more interested in saving
weight than in 100,000 mile longevity. My point was that 2-strokes can be made
to last. Imagine what Suzi would be building today if environmental laws hadn't
made them squander millions on four strokes.

BTW we ran ALL 2-stroke racebikes on premix for RELIABILITY. If one forget to
add oil to the injector you ruined the engine but if you forgot gas you just
failed to finish.

 

No, you alluded to owning several different kinds of bikes but no
actual model names or numbers. Try again.

For example I am currently down to one motorcycle. A Speed Triple.
This will be rectified at a later date after I am done buying a new
cage. You?

LOL! GPZ? I think I was in diapers for that model series. Gixxer? Well
they started back in 1986 so it could be a tad out of date there too.
Busa? That's not even in the same hemisphere as a TZ. Idiot!

When was the last time you threw a leg over an '06 R6?

Oh sure. In fact all quantifiable data is irrelevant when it disagrees
with the estimations of you and your spindly wife!

I've looked real hard on my bike when wrenching but I can't find a
pendulum. So I'm almost certain you're talking out of your ass.

Dang, you have an answer for everything.

Just not the correct answer.

Kenny Roberts is a champ? At which series exactly?

I thought he mostly just drinks his Metamucil from the sidelines these
days.

 

Reliability being the key word here, most 1970s 2 stroke oil pumps
were renowned for being temperamental yet you've been busy praising
the GT750 Suzuki for it's reliability. Your memory seems to have
become a bit jaded when it comes to old 2 strokes.

 

I'm sorry, but this is just complete bullshit.

Look up "motorcycle steering dampers" in google and have another think.