Originally Posted by
Snuffleupagus
That is to say you can make gradual moves, but you can't whip around and be a hazard to yourself and others. In general, if you're in front you have the right of way, and it's the overtaking rider's responsibility to not run into you. They can't do that however if you're going from white line to yellow line...
Those are the penalties, but there is no definition of the violation. The relevant rules are these.
1O6. No rider may make an abrupt motion so as to
interfere with the forward progress of another rider, either
intentionally or by accident [relegation or disqualification;
possible 20 days suspension if a crash results].
3B10. Foul Riding. A rider near the edge of a road who
leaves a gap sufficient for an opponent to pass may not
suddenly close the gap upon being overtaken [relegation or
disqualification].
Notice in both cases the movements are only prohibited if they interfere with a rider attempting to pass. Now while you always need to be aware of 1O7,
1O7. Dangerous Rider. Any rider who appears to present a
danger to the other competitors may be disqualified by the
Chief Referee, either before or during a race.
The last five words are important. The CR can not use 1O7 to disqualify someone after the race. It is meant to insure the safety of the other riders.