What does this mean?

gds said:

I see the term "Wheel pit is wheels in, wheels out" on race flyers.
What does it mean?

It just means that there is no neutral support and you must have put
wheels into either the pit, or support car in a road race, before you
can take any out during the race.
Since I use a dedicated set of race only wheels and tires that I don't
use for training I just put the set I use for training in the pit or
car.
It's a good idea to paint or marker some ID on the rims just to be
safe, and when you put wheels in you'll usually put a paper ID tag with
them too. I usually slide it between the spokes where they cross.
Another thing that is a huge help is to take an intro to racing clinic
like this one if it's available in your area.
http://www.northeastbicycleclub.org/home/events/?c=clinic
Good luck
Bill C

Thanks! For both the info and the wishes.
Gary