Writing an A-B Rallye

Length

50 RIs are a reasonable (rough) length for an A-B rallye.

Looping

There are three main types of RI in an A-B rallye:

1. Both parts refer to the same action(s), performed at the same location(s). The question is whether each part is valid.
2. Both parts occur along the same route, but not at the same location. The question is whether the first part is valid.
3. The parts occur along different routes, and one route loops to rejoin the other.

Simple gimmicks based on instructions that are invalid per the GIs (e.g., misspelled street names or words that "do not exist on signs") typically use either the first or second type of RI.

More complex gimmicks (especially those that have rallyists turn on specific streets) typically use either the second or third type or RI. The second type of RI makes the gimmick much more obvious: the first part refers to the same turn as an instruction of higher precedence. The instruction of higher precedence is done instead of the first part of the RI, so the second part of the RI is the one that can be done first.

The third type of RI loops the route to make the gimmick more subtle. Rallyists who catch the gimmick will follow a different route than those who don't. Neither RI part will refer to the turn for the gimmick. Often, those who miss a gimmick will never see the landmarks used in the RI part for those who got the gimmick.

Rallyemasters familiar with writing CM rallyes can use the third type of RI the way CM rallyes use Supp instructions. One RI part use an instruction like CS or Observe, referring to a landmark past the gimmick location. The other part gets rallyists who turn for the gimmick back on route in the most direct way possible (e.g., "U at Smith, R 1st Opp). In practice, this is very similar to the second type of RI. The main difference is that those who miss the gimmick never encounter the landmark used in the RI part for those who got the gimmick.

It is usually cleaner to let the two routes diverge temporarily. The two parts of the RI direct rallyists along different courses, which eventually rejoin.