Subject: rec.motorcycles FAQ of 93.10.01 (Part 1 of 6)
This is the rec.motorcycles Frequently Asked Questions list. It
will be posted near the first of each month. Please send requests
or submissions to [email protected]. (DoD #978, KotF)
Items marked with an asterisk (*) are new or changed from the
previous FAQ.
*** Terminology:
Q: I've seen some unfamiliar terms while reading the newsgroup.
What do they mean?
A: You think maybe we can read your mind? Well, here are a few
commonly-used terms:
cager motorist inside a car or pickup
Denizens the kind of people your mother warned you about
DoD I'd tell you, but then I'd have to kill you
The DoD FAQ appears in rec.moto at the beginning
of each month.
endo what happens when you get too exuberant with a
stoppie.
FOAF story "friend of a friend" story - usually bogus
highside falling over to the outside of a turn (bad)
lowside falling over to the inside of a turn (ditto)
[email protected] (H. Marc Lewis) adds:
"You don't have to be turning to highside (or
lowside). If the bike is leaning to one side
(turning, tankslapper, whatever) and you fall
off on the same side, then it's a lowside. If
the bike violently flips you over center to the
other side (and beyond!) then it's a highside.
I've seen and done both during 7 years of desert
racing. The highside is by far the worst of the
two..."
MSF Motorcycle Safety Foundation. They teach 'How
to Ride' schools, mandatory in some states.
spooge any semiliquid nasty substance
squid someone who rides far outside his abilities,
often to the detriment of himself and his
equipment.
stoppie a maximum-effort stop where the rear wheel is
lifted clear of the pavement.
WFO Wide F***ing Open - the normal throttle position
for Denizens, squids, and unfortunates on 50cc
Honda step-throughs.
=====================
Q: Who the hell is Lance Holst, and why is he a jerk?
A: That's for us to know and you to find out.
=====================
Q: Why doesn't the rec.motorcycle FAQ come out on the first of the
month like most other FAQs?
A: We use the Mayan calendar.
*** Riding:
Q: I've never ridden before, and I'd like to take a course. Where can
I find one?
A: In the USA, the Motorcycle Safety Foundation has courses several
times a year. To find the next/nearest course, call 800-447-4700.
Some states may also have their own required courses. Check with
your local DMV.
=====================
Q: I've never owned a motorcycle before, but I'd like to buy one.
What's a good first bike?
A: Don't let your hormones get the upper hand. Start small.
Try to find something short enough that you can touch the ground
with both feet when at rest. Experienced riders don't care, but
it's very comforting when you start out.
Try to find an older, used machine. It doesn't have to be perfect
as long as it's safe. Registration and (particularly!) insurance
are cheaper on older or smaller bikes. If you drop it, you won't
feel nearly as bad as you would if it was a new ZZX700RRR or
whatever.
Once you have some miles racked up, you'll be a lot better at
deciding what kind of machine you want to buy. You can sell the
old one, trade it in, or keep it for a spare.
=====================
Q: When I go around corners, should I lean my head with my body or
keep it perpendicular to the road?
A: Lots of people ride either way. At low speeds it probably doesn't
matter. The fastest racers keep their head level no matter which
way they're leaning. Keith Code's Superbike school also recommends
this.
=====================
Q: What's proper behavior for a passenger riding pillion?
A: [email protected] writes:
Here's what I tell passengers:
- Don't think or worry about leaning. Instead...
- Sit close and hug me tight. That way we are essentially a
single unit---and I control the lean for the both of us. [It's
particularly important when carrying a large male; if he's sitting
back it's like a large weight at the end of a spring sticking up
from the rear of the bike, which makes it wobbly and hard to
control. I explain this to guys to get them over the macho, guys-
can't-hug-guys thing. I explain this to women also: since women
tend to be lighter and have a low center of gravity, when a small-
to-medium woman sits close & hugs tight, I find almost no noticeable
effect on handling (though there *is* a noticeable effect on my
mood :) ]
- Ignore the things that look like handgrips beside the saddle.
- If you really want to participate, shift your head to look over
my inside shoulder in turns---shifting the ~25 pounds of head+
helmet gives plenty of contribution to the lean. Otherwise don't
worry about it, just pick a shoulder and stick with it, switch
when you get bored.
- Keep your feet on the pegs at all times! Don't put them down
when we stop at a light or anywhere else---I don't want them to
get mangled when I start moving.
- You may want to stand up on your pegs a little when we stop,
to keep from sliding forward on the seat.
- Let me know if you're uncomfortable with freeway speeds or
extreme leans or lane-splitting or whatever. [I try to not to
terrify newbies.]
- Open or close your faceshield as makes you happy.
- Enjoy!
The above works for me, riding a standard-style street bike ('83
Nighthawk 650).
I imagine things might be different for sport or touring bikes.
[comment: Looks quite complete. Probably the most important thing
is not to get a case of the red ass when hauling a newbie - it
can be scary as hell back there. Also be wary when carrying
experienced riders, as they may shift their weight to "help"
you without thinking about it.]
=====================
Q: What is lane splitting, and why would I want to do it?
A: Lane splitting is when you ride between the lanes of traffic. This
is legal in some states, not forbidden in others, and illegal in
still others. It can be an enormous time-saver when the freeway
turns into a parking lot at quitting time. Some people - including
some motorcycle magazine editors - advocate lane splitting and have
done so for years. Others, thinking of how erratic the average
cager is already, prefer not to take the chance of being creamed
when someone changes lanes or opens a door to dump a spittoon.
Some people make a distinction between lane splitting and lane
sharing. The same comments apply.
=====================
Q: I'd like to ride along with several friends, but I'm afraid we'll
get tangled up or run into each other. Are there any rules for
riding in groups?
A: There aren't any formal rules. Some states permit riding side by
side, other states require you ride staggered. Unless you're very
familiar with who you're riding with it's a good idea to ride
staggered.
In most states, groups must stop individually for stop signs or red
lights. It's bad practice to ride through a red light even if you're
in the middle of 200 riders. Large group rides sometimes have police
escort; if so, follow police signals. Sometimes it's hard to
differentiate "blow through this red light" from "there's a wasp up
my sleeve."
Generally, when riding parallel, the bike nearest the shoulder has
right-of-way. It's assumed that the inside bike can crowd the
divider and any oncoming traffic, while the outside bike may be
facing a ditch or stepped shoulder.
When riding staggered, the bike in front normally has the right-of-
way. You can see the guy in front just fine; he has to use his
mirrors to see you. By assuming you can take care of yourself, he
doesn't have to worry about collision if he has to dodge a pothole
or armadillo.
Remember, when you're riding in a group, you only have *half* a
lane. Worn pavement or crosswinds can make it difficult to keep
your mirrors or bodywork out of someone else's space.
(continued)
Subject: rec.motorcycles FAQ of 93.10.01 (Part 2 of 6)
=====================
Q: What is countersteering, and why would I want to do it?
A: That's a complex subject. Ed Green ([email protected])
has submitted a mini-FAQ on the subject:
How do motorcycles turn?
by Ed Green, a recognized non-expert in the field
A frequent topic of discussion, and the source of much confusion,
on rec.motorcycles concerns the mechanics, and underlying physics,
of how motorcycles turn. It would seem that such a basic maneuver
should be well understood by all motorcyclists. Surprisingly, many
experienced riders have no idea how they turn, they probably never
think about it. Many others have very definite ideas about how
they turn, which are likely incorrect. Even among the elite and
erudite Denizens, there is considerable disagreement as to the
mechanics involved with both leaning a motorcycle, and actually
turning one. Outlined here are the four major theories of motorcycle
turning which came out of a recent flame war, er, discussion, on the
subject (hopefully presented somewhat objectively).
To begin with, motorcycles, at greater than parking lot speeds, must
lean to turn. This is part of why they are so fun to ride. The four
predominate theories of turning are evenly divided between leaning
and turning, thusly:
1. Leaning (including countersteering)
1.1 Gyroscopic Precession
1.2 Steering-induced Roll
2. Turning
2.1 Camber Thrust
2.2 Steering Geometry
1. Leaning
Many people assume one leans a motorcycle by shifting body weight.
While it is possible to induce lean in this manner, the quickest,
easiest, and most controllable method of leaning a motorcycle is
by counter-steering. Counter-steering is a technique whereby the
rider exerts pressure on the *inside* handlebar (left for a left-
hand turn, right for a right-hand turn), to lean the motorcycle in
the desired direction. This is in effect steering the motorcycle
the "wrong" way, from the point of view of operating a tricycle,
thus the term "counter-steering." THAT it works is undeniable, and
can be proven easily with a short ride. Both the rate of
transitioning to the lean (how quickly the bike leans) and the
degree of the lean (how far over it leans) can be controlled by
the rate and degree of pressure applied to the grip.
HOW counter-steering works is debatable. The two leading theories
are gyroscopic precession and steering-induced roll.
1.1 Gyroscopic Precession
When riding at any appreciable speed, both wheels of the
motorcycle exhibit the properties of a gyroscope. This
contributes to the stability of a moving motorcycle. One such
property, called gyroscopic precession, is that when a lateral
force is applied to the axis of a free spinning gyroscope, the
axis moves in a direction 90 degrees from the applied force, in
the direction of the spin. For a motorcycle front wheel, this
means that a force applied which attempts to move the axis on one
side of the wheel back, toward the rear of the bike, will result
in an effort by that axis to move up. Similarly, a force applied
to move the hub forward results in a force trying to push it down.
Thus to execute, say, a right hand turn, the rider pushes on the
right grip, seemingly to steer the front wheel to the left. The
forks translate this input to hub of the wheel as a force pushing
forward on the right side of the wheel, and backward on the left
side. Gyroscopic precession will generate a force directed down
on the right side, and up on the left, which forces the bike to
lean to the right.
This gyroscopic business can most easily be demonstrated with a
bicycle. Position the bike in such a way that the front tire is in
the air and can rotate freely, and spin it up to a good speed.
Holding the handlebars, attempt to turn the wheel to the left, by
pushing on the right grip, and pulling on the left. You will feel
the wheel trying to push the whole assembly over to the right.
1.2 Steering-induced Roll
The point of contact between the motorcycle and the road is
called the contact patch, and is that small area of the front and
rear tire beneath the hubs (on level ground) which is resting on
the road surface. All actions which depend on frictional forces
between the tires and the road (such as acceleration, braking,
and cornering) depend on this contact patch, and the contact
patch is the point of application of the frictional forces. As
long as one accepts that the center of mass of the motorcycle+
rider system is somewhere above this contact patch, then any
frictional force which displaces the tires to the side acts at
the point of contact with the road, and will induce a pivot about
the center of mass (with a moment arm of the distance from the
contact patch to the center of mass). This pivot about the
longitudinal axis of the motorcycle is what is referred to in
aviation as roll (when one wing of the plane is higher than the
other).
This steering-induced roll is much easier to visualize than
gyroscopic forces, and is most simply described as "steering the
wheels out from under the bike, to make it lean the other way."
2. Turning
Through one or the other of these techniques, or some combination
of the two, the motorcycle is leaned over by counter-steering.
The motorcycle can also be leaned through weight shift, in which
case neither of the above theories hold. That is only half the
answer, however. Once the motorcycle is leaned, what makes it
turn? Assuming for a moment it doesn't just fall over, why
shouldn't it continue leaned over in a straight line until it
runs out of gas? The good folks of rec.motorcycles have been hard
at work on that one, too. The two leading theories for cornering
of a leaned-over bike are camber thrust and steering geometry.
2.1 Camber Thrust
Unlike the tires for cages and bulldozers, motorcycle tires have
a round profile. The diameter of the tire changes from a maximum
at the center (the contact patch if going straight), decreasing
to a minimum at the rim. When the bike (and thus the tire) are
leaned over, during a single revolution of the wheel, the center
portion of the tire must travel further than the part near the
edge. This induces what is called camber thrust, and it forces
the tire to trace out an arc in the direction of the smaller
diameter.
Camber thrust can be demonstrated by placing an empty ice cream
cone on its side, on a flat surface, and giving it a push. The
cone will not roll in the direction it was pushed, but will
constantly turn from that path, toward the smaller end.
2.2 Steering Geometry
The steering stem and handlebars of a motorcycle are not
positioned directly above the hub of the front wheel, but
are angled back to varying degrees, referred to as rake. Thus,
the weight of the motorcycle+rider is supported by the front
wheel, not straight up and down, but at an angle which points
through to a point ahead of the contact patch. The distance from
that point to the actual contact patch is called trail. During
straight-up and straight-ahead riding, this has no effect on
steering, because the force is transmitted along the center axis
of the motorcycle, which is the same as the center axis of the
front wheel. When leaned over, however, this configuration causes
a force to be applied to the rear part of the front tire, causing
it to lift, turning the wheel into the curve. The motorcycle then
naturally follows the front wheel. This view of turning is
essentially the same as that for other vehicles, using lean only
to counter the centripetal acceleration caused by the bike's
linear momentum.
This aspect of steering geometry can be demonstrated by holding
a bicycle (or motorcycle) upright, with the handlebars and front
tire free to move. Lean the bike to the right, and the front
tire will "fall" (actually, be pushed by the steering geometry)
to the right, and similarly for a lean to the left. Thus, the
lean of the motorcycle, even if initiated by a countersteer,
forces the front tire to point to the inside of the curve,
carving out a turn, and the lean also balances the centripetal
force which would otherwise push the bike over to the outside of
the turn.
So, in summary, a motorcycle must lean to turn. The quickest
way to lean a motorcycle is to use counter-steering. Counter-
steering leans the motorcycle through some combination of
gyroscopic precession and steering-induced roll. Once leaned
over, the motorcycle turns by some combination of camber thrust
and steering geometry. What is the exact combination of each of
these effects in actually causing leaning and turning? Pick
two, three, or all four of them, come up with your own mix, go
find a biker, and argue about it.
*** Mechanical:
Q: I pulled a wheelie the other day. Now my steering has a "catch" in
it, the the bike wants to veer to the side.
A: You probably notched the steering head bearings. Under a side load
(like whopping the front wheel back on the ground) the races can
get dented, balls flattened, or both. The only fix is to replace
the bearings. Taper rollers are much less susceptible to this sort
of damage, and conversion kits are sometimes available.
=====================
Q: My 1978 Suzuki GS750 is supposed to use grade SE oil. All I can
find is SG. Will it work? What about special motorcycle oils
like Golden Spectro?
A: The SE and SG are Service Ratings. SE has been superceded by SG,
which is generally a superior grade of oil. There should be no
troubles running SG.
The vendors of the specialty motorcycle oils claim their oils are
better than ordinary automotive oils. That could possibly be
true, particularly with regard to motorcycles using roller bearing
cranks. In most cases special motorcycle oils are probably a
waste of money.
Some motorcycles never seem to shift right, usually because they
have clutches that run in oil and automotive oil doesn't always
let them properly disengage. Various rec.moto participants have
reported greatly improved shifting and clutch action with special
motorcycle oils. Even expensive oil is cheaper than a clutch or
transmission.
Ed Hackett maintains a detailed FAQ on oil. You can annoy him at
[email protected].
(continued)
Subject: rec.motorcycles FAQ of 93.10.01 (Part 3 of 6)
=====================
Q: Can I use a synthetic oil in my motorcycle's engine?
A: Motorcycles in general tend to be highly stressed, run hot, are
abused when ridden, and tend to be stored for extended periods.
These are virtually tailor-made circumstances where synthetic oils
can shine.
Unfortunately, most modern motorcycles use a "wet" clutch, that is,
the clutch runs in oil. (despite how wacko this sounds, it's true)
Some synthetics can cause your clutch to slip. If you have a wet
clutch and really want to try synthetic oil, give it a try. If
your clutch slips you can always drain it and put regular oil back
in.
=====================
Q: I've been looking to buy a [brand and model name not important].
Several people have told me those bikes have troubles with second
gear. How can I tell if this one is OK, and why do they have this
problem?
A: Second gear problems are the most common of all. They tend to be
worse on high-power machines. Typically, the rider doesn't get
the gear all the way into engagement, and it pops out under hard
acceleration. This typically rips metal off the engagement
surfaces, making it that much easier to pop out the next time.
Eventually the machine will pop out of gear under acceleration.
Incorrectly adjusted clutches, careless shifting, and shifting
without the clutch can all cause second gear problems. The fact
that you could shift your dirt bike without the clutch is not
relevant; your dirt bike probably doesn't weigh 550 pounds, run
on pavement, and have a fat tire on the back.
=====================
Q: My motorcycle seems to use up chains pretty fast. How can I tell
the difference between a good chain and junk chain?
A: I wrote an article for Australian Motorcycle News which covered
this subject in detail. I've reproduced it here:
Years ago chains were considered disposable items. I remember
scraping up money for the spring chain and sprocket ritual every
year when I was in high school. Sometimes the chain wouldn't make
it through the summer, even with fanatic oiling. Every T-shirt I
owned had an oil stripe down the back on the left, much to my
mother's dissatisfaction. I once had a two-month-old chain on my
175 Kawasaki snap while going 50mph. The broken chain wrapped
itself around the swingarm and locked the rear wheel solid,
whereupon the rear wheel decided it would lead for a while. By some
miracle I came to a halt still vertical, but I have had a paranoid
distrust of chain drive ever since.
Now what, might you ask, would cause a chain to break like that? It
was properly lubricated, adjusted, and running on the correct size
(new) sprockets. Chances are that the local motorcycle shop had
sold me some ordinary industrial chain instead of motorcycle chain.
Such unscrupulous dealings were far more common years ago than they
are now. A real chain might cost $30 then, but farm machinery chain
sold for a little over a dollar a foot. What's the difference?
In its simplest form, the roller chain consists of side plates,
pins, and rollers. When properly lubricated, this type of chain
will perform acceptably for most engineering purposes.
Unfortunately, proper lubrication consists of an oil fog or bath
and freedom from dirt, both conditions unlikely on a motorcycle.
Twenty years ago some machines still came with enclosed chains, but
the enclosed chain died away not because of styling, but because it
was a tearing pain in the arse to service the chain or rear wheel
with the bulky (and oftimes leaky) enclosure in the way.
The oilite-bushed chain assisted the enclosed chain to oblivion. A
porous bushing was pressed into the roller and rode on the pin.
This porous bushing was impregnated with lubricant and would absorb
chain lube too. With a moderate amount of maintenance the bushed
chain was satisfactory if not perfect. Since the mid-1960s all
"real" motorcycle chain has been of the bushed type. The chain that
caused my hair-raising ride was likely of the previous type.
In the mid-1970s the "O-ring" chains came into use. These were
bushed chains using O-ring seals to keep the lubricant in and dirt
and water out. They represent the latest word in drive chain
design, being reliable, long lasting, and low-maintenance. Indeed,
when run on plastic sprockets, the O-ring chain may need no other
lubrication during its operational lifetime.
Modern motorcycle chains come in two basic types - those which are
endless, and those which use master links. Endless chains came
about when engineers realized that most catastrophic chain failures
ocurred at the master link. By eliminating the master link,
reliability could be enhanced. Unfortunately, endless chains can
cause a problem if the sprocket sizes have been changed much; if it
is too long or too short, nothing can be done. Endless chains also
usually require time-consuming removal of the swingarm for
replacement.
Motorcycle drive chain contains two kinds of links. Roller links
consist of two side plates, two rollers, and two bushings, all a
slip fit over the drive pins. Pin links consist of two side plates
and two drive pins, with the pins being a tight press fit into the
side plates and staked in place for permanence. These links
overlap, rollers on pins, to make the complete chain.
Most chain is made in inch-based sizes, because the standard chain
dimensions were established before much of the industrialized world
had adopted the metric system. The basic chain size is given in
terms of pitch, which is the on-centers distance between the
rollers. The roller diameter is standardized at 5/8 of the chain's
pitch dimension, so the common 5/8-pitch chain has a roller
diameter of .391 inches. Unfortunately, no such uniformity exists
in chain width, which varies a lot, as does sprocket thickness.
Running a chain on sprockets which are too wide is usually a feat
beyond even the most mechanically disinclined; unfortunately, it is
also possible to run a chain on sprockets which are too narrow. The
results of this are not good - the chain usually runs to one side
of the sprocket, concentrating a majority of the load on one side
of the chain, lowering its strength considerably and greatly
increasing both load and wear.
The loads on a chain are astounding. An average large-bore
motorcycle in first gear can easily develop 1500 pounds of pull on
the drive chain. The load-bearing area on the drive pins is about
.075 square inches in circular contact, in reality, much less. The
best-case loading for each pin is on the rough order of 20,000
pounds per square inch! With this kind of load, chain wear becomes
less of a mystery.
The loads imposed by the engine are only part of the stresses
inflicted on the chain. If you watch a motorcycle in motion, you
will see that the slack side of the chain does not simply droop.
Instead, it snakes and curves in a wavelike motion induced by its
tendency to try to wrap itself around the sprocket. Stresses
involved can be quite large. This threshing about adds to the
relative motion between the pins and links and wears the chain out
faster.
Motorcyclists often refer to "chain stretch." This term is somewhat
misleading. Chains do not actually stretch materially; any load
large enough to appreciably stretch a chain would be as likely to
snap it right in half. The stretch referred to is the growth in
overall length of the chain due to wear in its many moving parts.
The chain's pins pull very hard against the bushing walls and most
of the wear occurs at those contact points. Loads carried by the
bushing/roller contact surfaces are just as large but spread out
over so much area that the pressure at any given point is much less
than at the pins. In the normal course of events a chain's pins
will be worn to their service limits long before the rollers are in
any trouble. A chain is ready for replacement when stretch exceeds
2 to 2.5 percent. On a 5/8-pitch chain, this figures out as about
.0125-.0156" of slack per pin joint. Measuring each joint with a
micrometer is not necessary. For example, a chain measuring 65
inches has reached its service limit when its length has grown to
66.3 to 66.63 inches.
As the chain wears, the effective pitch between the links becomes
greater. The chain's pitch becomes slightly longer that of its
sprockets, causing the rollers to ride up on the teeth and apply
pressure where the sprocket is narrow and weak. A properly-designed
sprocket is designed to engage the chain's rollers gently, ease
them down to the base of each tooth - where the load is taken - and
then disengage smoothly and send the chain away. As the chain rides
up on the teeth, sprocket wear increases dramatically.
It would be nice if the sprocket makers would tell us how much a
chain may stretch before it would no longer fit within the design
limits of its the sprockets. Unfortunately, most sprockets come
bulk packed, or, if we are lucky, they might be blister-packed to
prevent them from being beaten up in shipment.
Chain wear can be kept to a minimum by keeping it clean and
properly lubricated. Gasoline, kerosene/paraffin, and cleaning
solvent are definite no-nos for cleaning chain. They can eat the O-
ring seals and then hang around to contaminate the lubricant. Wipe
any dirt of sand off with a cloth, then apply your favorite lube.
Specially-formulated chain lubes usually spray on like a thin oil
to better penetrate the crevices and then congeal to better prevent
being thrown off.
Inexpensive non-O-ring sealed chains require much more frequent
attention. On an unlubricated chain the friction between links can
cause temperatures to rise to the point where the links can
actually weld themselves together, putting a permanent kink in the
chain.
New chains have a breakin period, and that's when they have special
need for proper lubrication. If their pins are well-oiled the
loaded surfaces will be burnished smooth, leaving them in better
condition to resist wear. Without adequate lubrication the surfaces
will scuff and gall, greatly accelerating wear.
The chain final drive has come to become the mark of the sporting
machine. It is lightweight, mechanically efficient, inexpensive,
and compact. Chain technology is still developing, and it's likely
we'll see chain drive used for a long time.
=====================
Q: My engine has a magnetic drain plug. Whenever I change the oil,
it's always covered with tiny metal splinters and spooge. Does
this indicate problems in the engine?
A: Probably not. The magnet's purpose is to attract ferrous spooge.
The gooey mess is tiny iron filings from your cams, cylinder walls,
and other wearing surfaces. It's basically the same sort of gick
your oil filter traps. Small splinters and pinhead-sized chunks
are usually pieces of your transmission's engagement dogs. It's
normal to have *some* splinters even on carefully-ridden machines.
A lot of them indicates missed shifts or worn shifter components.
Pinhead-size or larger flakes usually mean the case hardening is
coming off the gears. That's a bad sign.
(continued)
Subject: rec.motorcycles FAQ of 93.10.01 (Part 4 of 6)
=====================
Q: The front brakes on my bike make a buzzing noise. I've looked all
over and can't see any loose parts. What is it?
A: You probably have drilled or slotted rotors. The holes often make
a noise as they move past the pads. Some bikes have floating rotors
which can make intermittent noises. In either case it's nothing to
worry about.
Q: Are drilled or slotted rotors more efficient than solid rotors?
A: There are many different reasons rotors are drilled or slotted.
Sometimes the rotors are drilled to lighten them, though your weight
savings is probably negligible. Honda claims the discontinuities
help braking in the rain and provide an escape route for mud or rust.
Fred Puhn's "Brake Handbook" says, "Some rotors have slots or holes
machined into their contact surfaces. These reduce hot-gas and dust-
particle buildup between pad and rotor. Although fade caused by
gas buildup is less for a disc brake than for a drum brake, some
fade still occurs. This is more prevalent with large brake pads,
because the hot gas has a harder time escaping than with small pads.
Therefore, slots or holes have greater effect in racing, where pads
are large and temperatures are very high."
Newcomb & Spurr's "Braking of Road Vehicles", 1967, tells us the
mass of the rotor is the primary factor for preventing brake fade.
When the rotor mass has absorbed enough heat, the brake will fade.
Vented rotors and ducting schemes will cool the rotor faster, but
it takes time; in rapid repeated braking cycles vented rotors do
little better than solid ones.
Carroll Smith's "Prepare To Win", 1975, says "Lately you may have
seen discs with tangential slots milled in the friction surfaces
or holes drilled in a tangential pattern normal to the friction
surface. This is an effort to wipe the "fireband" or boundary
layer off the disc before it reaches the point of contact with
the pad and to provide the very hot particles of friction material
worn off with some place to go other than the operating area."
=====================
Q: I have a 1973 Kawasaki Z-1. My owner's manual says it should run
premium leaded fuel. Will it hurt the engine to run unleaded?
The local shop says they need to install hardened valve seats
for $400.
A: No. Your Kawasaki already *has* hardened valve seats. Engines with
aluminum cylinder heads must have seat inserts, as aluminum is not
a suitable seat material. Someone is trying to rip you off.
*** Lights:
Q: I've seen ads for light modulators that flash the headlight and
brake light. Are these really useful? Should I buy one?
A: In general, no. Many states and municipalities prohibit flashing
lights (other than turn signals) except on authorized emergency
vehicles. Check your local laws before you buy. Even if you're
legal at home you still might pick up a ticket elsewhere.
Flashing lights often infuriate cagers, who will then mess with
you. Generally, the cagers win.
The flashing is also *very* bad for halogen bulbs. Expect your
headlight life to be significantly decreased.
*** Personal Equipment:
Q: I'm considering the purchase of a new helmet. The one I have
doesn't feel too good for some reason, even though it's the right
size. How can I tell when a helmet fits right?
A: First off, helmet sizes are like shoe sizes - they're only a general
guideline. Don't expect a size 8 to be the same size from two
different manufacturers.
Every brand of helmet is shaped differently inside. Of each brand,
most models are also different. The only way to find a properly
fitting helmet is to cruise the local shops and start trying them
on. Try ALL of them on, not just the expensive or pretty ones.
Proper fit is more important than gaudy stripes or fancy
certification. A properly fitting DOT-rated helmet is safer than
a badly fitting Snell-rated helmet.
The helmet should fit snugly. It shouldn't clamp your ears like a
vise, perch on top of your head like a ferret wearing a coffee cup,
or try to cave in your forehead. It shouldn't have any loose areas
either. As long as the chin bar doesn't try to move your jaw back
to your ears you're OK; in some helmets you're not *supposed* to be
able to touch the chin bar.
Many newer-design helmets have extensive padding in the cheek
area. This padding can cause interference with glasses. You can
sometimes get the cloth liner loose and cut reliefs with a razor
blade. You can also pull the liner loose and add extra foam to
adjust the fit in any loose areas. It's not a good idea to try to
cut the styrofoam section away to adjust the fit - find a different
helmet.
Some people get upset at the idea of altering the fit of their
helmet. The decision is up to you.
=====================
Q: The wind and engine noise from my bike get to me after a while. Is
it safe to wear earplugs when I'm riding?
A: I've never had a problem. I keep a couple sets of cheap foam plugs
in my bike's storage compartment; when I expect a ride to last more
than half an hour or so I put them in. They lessen the noise a lot
without blocking out sirens or screeching brakes.
In some places it is legal to drive if you're deaf, but not if you
are wearing earplugs. Check your local laws.
=====================
Q: What's a good buy for a leather jacket?
A: [email protected] writes:
Things to look for in a leather jacket:
OVERALL SUMMARY:
- Thick leather is a must. This is what makes the difference between
a motorcycle jacket and a fashion jacket.
Protection:
- Thick leather: heavy motorcycle leather (not "fashion" weight)
3-3.5oz weight or ~1-1.3mm thickness
- Elbow pads
- Shoulder pads
Cut & Fit:
up your back or the sleeves sliding up and leaving a gap at
the wrist.
- Sleeves really long
- Back should feel a little "hunch-backed" when standing upright
(more important on sport bikes than cruisers)
- Try it sitting on the bike.
- Fits closely in the forearms (sleeves zippered)
- Down only to hips if you dislike bunching up that longer
touring gear does.
- Make sure to leave room inside the jacked for sweaters & such.
- Don't buy anything you haven't tried on [conflicts w/ later
suggestions for buying mail order]
Comfort/Convenience:
- Zipper front
- Flap behind zipper to keep out the cold
- High collar
- Snap-down collar to keep it from slapping your cheek/neck
- Vents (zippered) to let in air during summer; grommets at armpits
- Removable (zip out) lining
- Zippers at wrists to keep sleeves from sliding up (while you're
sliding down the road)
- Lower back support panel for when you fall down.
- Stiff leather won't flap in the wind.
- (Tie a leather thong through hole in zipper tab for easy zipping
w/gloves)
Durability:
- Full-grain hides are preferred for repeated abrasion resistance,
but split or top grain will probably work the first time you
fall down.
- Double-stitching
Where to buy cheap:
- Sears surplus outlet
- J.C. Whitney catalog
- Mail-order places (see ads in riding magazines)
- Pawn shops
- Check police stations for Highway Patrol officers wanting to
sell used gear.
(If calling used/pawn/surplus stores: Try to get as much info as
possible over the phone. Give your size, etc. Be sure to say
motorcycle jacket, otherwise they will say "Sure, come on over
we've a fur lined brown leather coat and a pair of disco leather
patch pants.")
Miscellaneous:
- [The MSF course I took emphasized comfort first, protection
second -- being uncomfortable increases the likelihood of an
accident, and it's most important to decrease that likelihood.
Next important is protection, so that if an accident does happen,
the damage is minimized. Discomfort includes too hot, too cold,
too wet, too dry.]
- Get a jacket you really like (off the bike too); if you're like
a lot of folks, you'll wear it all the time anyway.
- Don't worry about stiffness; some new jackets need to break in.
- Hein Gericke jackets have it all, if you're willing to pay the
price. Sometimes discounters may have them cheaper than most
dealerships.
(continued)
Subject: rec.motorcycles FAQ of 93.10.01 (Part 5 of 6)
=====================
Q: Is there anything that will clean a face-shield and also remove
abrasions so that one can see through it better?
A: [email protected] (Blaine Gardner) replies:
What you want are Meguiar's Mirror Glaze Plastic Polish and Plastic
Cleaner. They are very mild abrasives meant to remove scratches from
plastic. For fine scratches just use the Polish, for bigger ones
start with the Cleaner and finish with the Polish. The stuff is $5-8
bucks per bottle at most auto or motorcycle parts stores. Don't
choke over the price too much, since both bottles will probably last
you 10 years. The stuff works great on plastic watch "crystals" and
compact discs too.
=====================
Q: What kind of abrasion resistance can I expect from various
protective gear?
A: [email protected] (Blaine Gardner) replies:
In the Sept. 1988 issue of Cycle they "road tested" several grades
of leather, nylon and Kevlar. The two tests were dragging the
material at 50 mph until it failed, and running a sample on an
abrasion tester until failure.
At 50 mph the results were:
"Natural Armor"
3 oz leather 86' 0"
"Strong Synthetics"
Kevlar 22' 1"
Codura Nylon 18' 3"
"The Rest"
1.75 oz leather 4' 4"
2.25 oz suede 4' 3"
Denim, 2 year old 4' 0.5"
Denim, new 3' 10"
Ballistic Nylon 3' 10"
The results were a bit different on an abrasion tester, but the
overall ranking was 3 oz leather, then the synthetics, and far
behind those were denim and thin leather. Note that the best
synthetics are 1/4 as effective as HEAVY leather, while light
weight leather is considerably worse than the synthetics, and far
worse that heavy leather. Of course multiple layers of any material
is better than a single layer.
Another point not covered by the table is that a material with a
hard, slick finish is important because it resists snagging and
tearing. The reason that Cordura nylon did so much better than the
thicker Ballistic nylon is that the coarse weave of the Ballistic
caught on a flaw in the road, and tore. The suede finish leather
suffered a similar fate on the road. On the other hand, Ballistic
nylon did much better on the abrasion tester where snagging was not
an issue.
[note from the Keeper: even the most abrasion-resistant clothing
won't help if you're rapidly decelerated by a cage or a tree. A
set of leathers won't make you proof against getting squashed, so
be careful out there]
=====================
*** Tires:
Q: I'm having new tires put on my bike. Is there anything I should
watch for?
A: YES! Make sure the yoyos mounting the tire don't lay the wheel
flat on the floor or let it fall over. This is a good way to bend
a $200 brake rotor. Good dealers also use plastic rim protectors
under the tire irons. This keeps from scarring your expensive
polished or painted wheels.
Some motorcycle tires are directional; that is, they are only
supposed to rotate in one direction. Such tires are marked with
an arrow. If your tire has an arrow, make sure it points the
right way when you put the wheel back on.
=====================
*** Law:
Q: I'll be vacationing in [some foreign country] and would like to rent
a motorcycle there. Is my [home country] license OK?
A: In normal circumstances, as long as you are legal in your home
country/province/state, you'll be legal elsewhere. There's also
an International Driver's License - check your local licensing or
motor vehicle authority for details.
=====================
*** Other:
Q: I am interested in/just bought a 19xx Yamahondasakiuki CNGSZxxxx
and I was wondering how good it is and what I should watch out
for?
A: [email protected] (Loki Jorgenson) replies:
You can do one of two things -
1) Check the anonymous FTP site ftp.physics.mcgill.ca (132.206.9.13)
under ~ftp/pub/DoD for reviews for various bikes, as contributed
by rec.moto members. If you don't have ftp access, you can send
a request for a specific bike or the list of available reviews
to [email protected]
2) If your bike hasn't already been reviewed, ask rec.motocycles,
collect the responses, summarize them and forward them to
[email protected].
Also, please feel free to submit your own review of any bike that
you have already ridden. There is a TEMPLATE file available at
the ftp site to serve as a guide for the information structure.
=====================
Q: I'd like to get a bike cover. Where can I get one?
A: Look in the magazine ads. Here are some points to consider before
buying a cover:
Plusses:
keeps the sun, bird crap, and dust off your bike
keeps feebos from sitting on it and covering it with
drool and fingerprints
may protect the bike from gratuitous vandalism
Minuses:
cover acts as a giant sail; makes it easier for the wind
to tip the bike over
dew and rain seep-through will collect under the cover,
causing the bike to rust faster
covers seem to be popular with thieves, who will sometimes
destroy them trying to get them off
you have to have some place to put the cover when you take
it off.
I use a $8 K-Mart plastic tarp. Two ends are tied to concrete
blocks, the other two ends to chunks of 2x4. When I leave I
simply flip the tarp off; when I get back I flip it back. It
keeps the sun off while allowing plenty of air circulation.
(continued)
Subject: rec.motorcycles FAQ of 93.10.01 (Part 6 of 6)
=====================
Q: I'm interested in adding a sidecar to my bike. What's the deal?
A: [email protected] (Paul Spencer) says:
I posted this once before, and have been mailing it out to those
who ask. I'd love to work on it more, but my current schedule is
a little insane. Have fun. I'll critique the sidecar FAQ you come
up with if I have time. ....paul
===== sidecars =====
Having a sidecar is a lot of fun. You can ride all year, you can
use it for errands a lot more, you can carry more people, you can
go on much longer trips with others (since they can sleep in the
sidecar). People come up and talk to you a lot more; they don't
have the greasy biker' syndrome.
However: sidecars are _NOT_ motorcycles. They handle very
differently. I had over ten years and over 100,000 miles of
riding experience before I got a sidecar; it wasn't very useful. Be
prepared for a totally new experience. You can get yourself into
trouble just as easily as you can on a bike; but you have many fewer
options on getting yourself OUT of trouble.
Unfortunately, many bikes these days are poorly made for attaching a
sidecar. The entire outfit will be very difficult and dangerous to
ride. Get expert advice in this field. (Even if you buy a bike and
sidecar as a unit, it may be set up wrong; I'd say from informal
looking around at sidecar rallies that about 50% of outfits are
badly put together, and 20% are downright unsafe).
The idea of having a sidecar that is removable is a poor one; a
good sidecar unit is just that, a unit, which is never taken
apart. Many desirable modifications that make the sidecar unit
better - such as reduced trail, and flat-profile automotive tires
- make the bike unrideable as a solo anyway.
The only motorcycle manufacturer who sells sidecars is Harley
Davidson. They are excellent sidecars, and Harleys are ideal for
pulling them. Adding a sidecar to a Honda/Yamaha/Kawasaki/Suzuki
/BMW motorcycle will void it's warranty; it will also make most
shops refuse to work on your bike.
Sources of more information:
United Sidecar Association (USCA)
130 S. Michigan Avenue
Villa Park, IL 60181
Regular magazine, books on building a unit, books on riding with
a sidecar, books listing all available sidecars on the market.
Also offer training courses on riding. National and regional rallies.
Hack'd Magazine
P.O. Box 17640
Portland, OR 97217
Monthly magazine. Better mag than the USCA.
California Sidecar
Garden Grove, CA
(800) 824-1523
Wide range of sport and touring sidecars; handling packages.
Motorvation Engineering
3702 Clifton Place
Montrose, CA 91020
(818) 248-9631
Both sport and touring sidecars.
BMW Motorrad of St. Louis / EML USA
4011 Forest Park Blvd.
St. Louis, MO 63108
(314) 531-4010
Sell EML and Ural sidecars, along with a lot of parts for Steibs.
Lots of handling improvement stuff. Great place, lots of free
advice.
Hitchhiker Sidecar Company
1665 Cumberland S.E.
London, OH 43140
(614) 852-5373
Only make one touring-oriented sidecar, but it's well liked.
=============================================
END OF FILE
=============================================
Return to top