Today I had my first experience as ‘Ride Assistant’ on the Team MK ride to Carlton. It was on one of the more traditional club routes to the venue, not the one that I made up. I am guessing there were about thirty of us altogether although I didn’t really count accurately. Quite a big group though.
(Note: I did the ride from Olney to Stony Stratford first and I dropped off at Olney on the way back leaving them to do what I had already done)
I spent my time riding as ‘shot-gun’ at or very near to the back of the group as is the duty of the ride assistant. It was my job to ride at the back to notify the group of traffic coming up from behind and to keep any stragglers in touch or to help with punctures or mechanical problems. Traffic coming up from the rear and waiting to pass is warned about with a shout of ‘Car Up !‘ Traffic coming in the opposite direction is warned of by a shout of ‘Car Down! ‘ from the front of the group. This call isn’t so necessary on the larger roads but on the smaller country roads its quite important. Both calls are just to let other riders know they should keep well over to the left or ride in single file to allow the cars to pass. The way to remember which call to use when is to remember that cars coming toward you are going down your throat and cars coming from behind are going up your a**e ! Any vehicle is referred to as ‘car’ be it bus, truck car or van.
As it happens the ride was quite uneventful as far as I was concerned, no problems to deal with of any consequence. Two or three guys dropped off the back now and again for a ‘call of nature’ by the roadside but they were experienced club members and well capable of chasing back onto the group.


In my limited experience, the American phrase (why do we need a separate word for everything?) for a car coming from behind is, “Car Back!” The phrase for a car coming towards is the group is “Car Up!” Which is the exact opposite of what you describe. When approaching intersections, “Car Left/Right” is also often heard.
“Car Back” is also used here by some.. and at intersections car left/right is used should that be the case and also “clear” if appropriate.
Maybe Americans are too pure of thought to have to use that method of remembering the rule.. whereas we have no shame..