No real set guidelines. The rule book basically says that officials can pull a rider when they are deemed to be out of contention or if a rider may pose a danger to himself or to other riders.

On wider courses with smaller fields officials will sometimes try to be nice and leave everyone in. Towards the end of a race officials may pull a rider if there is a chance they will get caught during the final couple of laps and may get in the way of the final sprint. Also officials may pull riders off the back towards the end of the race if the schedule is running behind and they want to get the current race off the course as quickly as possible so the next race can get a warm-up lap and get started as quickly as possible.

In some cases if there is a problem with crowd control the officials may pull riders off the back. It isn't a good situation to leave a rider in a race only to have them wipe out themselves or a careless spectator.

The main consideration for the officials is rider safety. If it will make for a safer situation to pull a rider then the officials will normally do that. Also if a lot of lapped riders will make the race scoring difficult then lapped riders ( or riders who are going to be lapped) will be pulled.

Personally I will generally start thinking about pulling a rider if they fall more than 1/2 lap behind the leaders. If the field is smaller and the course wide enough I will sometimes let a rider get lapped once ( figuring that the rider may have gotten a poor warm-up) but if the rider is going to go down a second lap I will then pull them.

Are there specific guidelines for officials as to when a rider should be pulled from a crit, or is it more left up to the individual official's discretion? Seems like some races riders are pulled pretty quickly, and others not... Just curious!