Bob Shanteau, PhD, PE has decades of traffic engineering experience and accomplishments crafting the traffic laws that we have today.  In the somewhat lengthy essay below, he explains much better than I have how cyclists have come to have to battle for our right to the road and how some bicycling advocates can be unwittingly working to lose that right.  In the essay below, he is responding to 5 questions asked by another member of a group to which I belong, 
bicycledriving@googlegroups.com.
Frank
> 1) Bob, is it fair to say that you think cyclists should never share the road when it is safe to do so, or are you okay with sharing the lane and road when it is safe for you to do so?
 
By "share the road", I assume you mean moving to the right edge of the 
roadway or on a paved shoulder to allow faster traffic to pass.
 
In general terms, I believe that bicyclists should "share the road" 
whenever a driver of a vehicle in similar circumstances should. The 
problem is that, for all practical purposes, there are no drivers of 
vehicles in circumstances that are similar to what a bicyclist faces. 
The dominant vehicle on the roads today is the motor vehicle, virtually 
all of which can travel at freeway speeds. As a result, people treat 
every road as though it were a freeway, where the rule is, "if you can't 
keep up, you don't belong." Since bicyclists usually can't keep up, they 
are expected to stay out of the way. Bicyclists are narrow enough that 
they can sulk along at the edge of the road, out of the way of faster 
traffic. It's as bicyclists had a "deal" with motorists: Motorists will 
tolerate bicyclists on the roads as long as bicyclists stay out of their 
way.
 
I recall a conversation with a CHP Lieutenant a few years ago who said 
that he would stop anyone going slower than other traffic for impeding, 
and anyone going faster than the speed limit for speeding. It is a 
common belief that the roads are safer and more orderly if everyone goes 
at about the same speed. And a few months ago, during a meeting of the 
California Statewide Bicycle Task Force, a CHP Captain said that he was 
not willing to accept revising California's impeding traffic law, which 
now applies to all drivers (including bicyclists), so that it applied 
only to drivers of motor vehicles, as in the Uniform Vehicle Code and 
the traffic laws of about 44 other states. So it should come as no 
surprise that almost no one knows how to treat a vehicle that is 
traveling slower than other traffic, and almost everyone believes that 
bicyclists acting as drivers of vehicles would disrupt the safe and 
orderly flow of traffic.
 
When I asked Beck about how the rules of the road apply to a slow 
motorcyclist, he answered:
 
> motorcycle and have little concern for the rights of motorcyclists. i 
> suspect smv, low cc motor vehicles have fairly strict road use 
> requirements in CA far stricter than the cyclist allowances,
 
Actually, the provision granting motorcyclists to use of a full lane is 
in the Uniform Vehicle Code, but not the California Vehicle Code. The 
CHP FAQ <http://www.chp.ca.gov/html/answers.html> says that 
motorcyclists can split lanes to pass slower traffic, but says nothing 
about whether slower motorcyclists must move to the right edge of the 
right lane to allow faster traffic to pass. (A shoulder is not part of 
the roadway, and vehicles are allowed only on roadways in California.)
 
Beck's comment about slow moving low cc motor vehicles having stricter 
road use requirements in CA than bicycles is true. That is but one more 
symptom of freeway thinking carried over to conventional streets and 
highways. It is one more manifestation of the belief, "if you can't keep 
up, you don't belong." Bicycles are just about the only slow moving 
vehicles (devices in CA) on the roads today. That is because bicycles 
were originally recognized as vehicles and organizations such as the LAW 
have, for the most part, been able to fight off challenges to the right 
of bicyclists to use the roads. But now that status is being challenged 
by well intentioned people who believe that, for their own good, 
bicyclists should be treated as something other than drivers of 
vehicles. If these people get their way, we may very well see bicyclists 
deprived of the right to use the roads as drivers of vehicles.
 
With that introduction and the proviso that I am not a lawyer, I will 
now attempt to answer your questions. In your questions, you do not 
specify whether the road in question has lanes or not. Originally, all 
roads were unlaned, and on such roads the law is that drivers of slow 
moving vehicles, including bicyclists, must drive as close as 
practicable to the right-hand edge or curb, except when overtaking and 
passing another vehicle proceeding in the same direction or when 
preparing for a left turn at an intersection or into a private road or 
driveway. (CVC 21654(a) and UVC 11-301(b))
 
On a laned road, it has been the law since the 1930's that drivers (and 
bicyclists) proceeding upon a highway at a speed less than the normal 
speed of traffic moving in the same direction at such time shall be 
driven in the right-hand lane for traffic, except when overtaking and 
passing another vehicle proceeding in the same direction or when 
preparing for a left turn at an intersection or into a private road or 
driveway. (CVC 21654(a) and UVC 11-301(b)) California has a law 
requiring drivers of slow moving vehicles on two-lane roads to take the 
next safe turnout when 5 or more vehicles are following. (CVC 21656)
 
> 2) Should mature, adult cyclists ride safely right to share the road if safe when faster traffic is present?
 
At the start of a recent meeting of the Statewide Bicycle Task Force, 
the same CHP Lieutenant talked about how everyone on the road needs to 
be courteous. And the same CHP Captain complained about a group of 
bicyclists on a two lane road in the Napa Valley were delaying him and a 
bunch of other motorists. Alan Wachtel, Jim Baross and I explained that 
if there were 5 or more vehicles following, those bicyclists were 
required to take the next safe turnout to allow faster traffic to pass. 
Apparently that was news to the CHP Captain, and if we had been able to 
ask the bicyclists, it probably would have been news to them, too.
 
To answer your question, I believe that a bicyclist on a two lane road 
has the same duty as the driver of a vehicle to take the next safe 
turnout when 5 or more vehicles are following. On a multilane road, I 
believe that a bicyclist has the same duty as the driver of a vehicle to 
use the right lane.
 
Consider someone driving a fully loaded truck, a recreational vehicle or 
an old VW bus slowly climbing a steep upgrade. On a two lane road, that 
driver is required to use the next safe turnout when 5 or more vehicles 
are following (although that law is honored more in the breach than in 
the observance). On a multilane road, that driver is required to use the 
right lane. In fact, there is even an exception in the impeding traffic 
law for grades. (CVC 22400)
 
As a courtesy, some drivers of slow moving vehicles, particularly on two 
lane roads, will drive on a shoulder to allow faster traffic to pass (if 
the shoulder is paved and the pavement is in good shape). In California, 
bicyclists are explicitly allowed to operate on shoulders (CVC 
21650(g)), and as a courtesy, that is generally where bicyclists ride if 
the shoulder is paved and the pavement is in good shape, even on 
multilane roads. But the law does not require bicyclists to use, in Andy 
Clarke's words, "a perfectly rideable shoulder." Otherwise, courts would 
be in the position of second guessing bicyclists about when the shoulder 
was perfectly rideable. It would also be a denial of the right of 
bicyclists to use the roadway as drivers of vehicles, which is something 
that groups like the LAW have been defending since the 1880's.
 
> 3) is the notion of road sharing somehow beneath vehicular cyclists?
 
You didn't say, but I will assume that you mean sharing a lane side by 
side with faster traffic. Drivers of slow moving vehicles are required 
to use the right lane. As a courtesy, I may decide to ride my bicycle on 
a shoulder if it is wide enough and the pavement is in good shape. 
Particularly on two lane roads, turning out every so often to allow 
faster traffic to pass is an expected action of the driver of any slow 
moving vehicle, including a bicycle.
 
> 4) is your operating mantra One bike, the entire lane, no matter how wide, always?
 
If we have a "mantra," it is that bicyclists should have the same rights 
and duties as drivers of vehicles (CVC 21200 and UVC 11-1202) We object 
to laws that micromanage the position of bicyclists on the road (CVC 
21202 and UVC 11-1205) or that require bicyclists to use bike lanes (CVC 
21208) or sidepaths. We believe such bicyclist-specific laws were 
enacted not for the safety of bicyclists, but to facilitate the movement 
of faster traffic. As such, we believe such laws discriminate against 
bicyclists.
 
I helped write the exceptions contained in CVC 21202 and CVC 21208 in 
the early 1970's. At the time, there were no exceptions in CVC 21202 and 
there was no state law at all regarding bike lanes. I recall a meeting 
with the aide to the state senator who was authoring the legislation, 
and he said that the legislature would not go along with a bill without 
bicyclist-specific restrictions, and including the exceptions was the 
only way to prevent more onerous bicyclist-specific restrictions.
 
I have since come to realize that the reason the legislature would not 
have gone along with having no bicycle-specific restrictions was the 
common lack of understanding among the public about how drivers of slow 
moving vehicles in general (and bicyclists in particular) should act and 
be treated. Most people believe that because it is usually physically 
possible for bicyclists to share the right hand lane side by side with 
passing vehicles of typical width (5 or 6 feet), that, out of common 
courtesy, bicyclists should always share the lane, even with vehicles of 
maximum legal width (8 1/2 feet by CVC 35100).
 
If you watch how bicyclists behave on the roads, you will see that most 
of them engage in "edge riding" behavior. They ride in door zones, pass 
right turning vehicles on the right, and weave in and out of parked 
cars. They are staying out of the way, just as the "deal" with motorists 
dictates. And the penalty for bicyclists who violate that "deal" by 
getting in the way? They must be taught their place, of course. Thus the 
honking and shouting and other aggressive behavior that a minority of 
motorists subject on bicyclists who dare to violate the "deal" by 
operating their bicycles as drivers of vehicles. On the other hand, it's 
amazing to experience how most drivers respond to bicyclists acting as 
drivers. They simply treat such bicyclists as fellow drivers.
 
Based on viewing old films of traffic, the "deal" between motorists and 
bicyclists apparently existed from the time when motor vehicles started 
to dominate the roads. It was formalized in 1944 when the original 
version of UVC 11-1205 was incorporated into the Uniform Vehicle Code 
and subsequently into the vehicle codes of most states. It required 
bicyclists to ride as far right as practicable on the roadway, without 
exception, as though bicycles were always slow moving and all roads were 
unlaned. At the same time, though, lane lines were being painted on more 
and more roads. Apparently the authors of UVC 11-1205 wanted bicyclists 
not to have the same lane use rights as drivers of vehicles. That is 
still the common belief today, despite the exceptions that were added in 
the 1970's.
 
Things did not work out the way that we who wrote the exceptions hoped 
it would. Almost all bicyclists still engage in edge behavior or ride on 
sidewalks, and almost all motorists still expect bicyclists to stay out 
of their way. When faced with a narrow right hand lane with no shoulder, 
most people still say that there is no room on the road for bicyclists 
and that there is a need to create room with a bike lane or sidepath. 
Without special facilities, we see that bicyclists ride at the right 
edge, even if it means riding in the gutter or in the door zone. Most 
people behave as if they are still going along with the "deal" between 
motorists and bicyclists.
 
Advocates of bicycle driving, on the other hand, want to break that 
"deal". We see a future when once again bicyclists act and are treated 
as drivers of vehicles. We want it to be OK for bicyclists to get in the 
way of cars. And the first step toward that future is repeal of the laws 
that discriminate against bicyclists so that legally, bicyclists have 
the same rights and duties as drivers of vehicles. Not more, not less. 
That will require educating legislators that bicyclists can and should 
be treated as drivers of vehicles. Subsequent action includes changes in 
highway design standards so that freeway style features are eliminated 
from streets and highways on which bicycles are allowed. And bicycles 
are detected at all traffic actuated signals. And changes are made in 
driver education so that motorists learn to deal with bicyclists using 
the full lane. And youngsters are taught how to operate their bicycles 
as drivers of vehicles with full lane use rights. And law enforcement 
officers and judges are educated about when bicyclists and motorists are 
operating within the law.
 
Our biggest hurdle is getting other people to recognize that the world 
would be a better place if the "deal" were broken. We believe that 
bicyclists would be better off, but a lot of bicycle advocates disagree. 
They think that bicyclists would be better off instead of breaking the 
"deal", bicyclists were provided with segregated facilities. Most other 
people see nothing wrong with the "deal", so they go along with the 
segregated facilities.
 
Who will prevail? Well, there are a lot more people who want to keep the 
"deal" in place than not. But that does not prevent us from pointing out 
the advantages to bicyclists of breaking the "deal".
 
Bob Shanteau
P.S. by Frank Gmeindl: 
CHP = California Highway Control (Bob is in CA)
CVC = California Vehicle Code
UVC  = Uniform Vehicle Code: a national guide.  States may choose parts to implement.  WV has chosen not to include the exceptions to the "Far to the Right" provision that the UVC offers but PA and MD have.
In WV, bicycles are not considered to be vehicles.
LAW = League of American Wheelmen (now LAB, League of American Bicyclists)