All players will be required to have a number printed on the back of their shirts (lower back is preferable as it is easier to see when on the bike).
It doesn't matter which number you choose (keep it short and simple,** 0-9**), just make sure it is big enough for the ref to see.
Do it yourselves before the tourney and get it done properly, or let us do it our way...
http://www.ehbpc.org/2011/shirt-numbers/