Just been looking at doing series entry for 2013. The youngest you can be, is born in 1999 for juvenile for next years entry. My daughter born 2000 will then race 1st year juvenile in 2014. Simple.
But that will be her first year youth/U16 at cx (so she will have raced 2 seasons as a U14), she has raced national trophy this season as a youth b rider. Just doesn't seem right? She beat female senior riders in local races last summer. Cycling will lose her if she has to ride U12's again, boring.
If you think you have a case for your daughter to race juvenile then you need to take it up with BC; I believe occasionally they may give dispensation to race up a category.
I don't think you can compare CX and XC so easily though when it comes to younger rides taking part. CX doesn't really take riders well away from 'civilisation' whereas during an XC race you can find yourself quite alone at times and a decent distance (well it seems like it) from the next marshal/arena. I imagine the 'supervision' differences between the two sports could be the reason for the differences in the categories. That said I could be talking absolute rubbish, however it is only BC who will be able to answer the question for you.
I think the juvenile category is now the same as other BC under 14 categories, ie from 1st Jan of the year of your 13th birthday to 31st Dec of the year of your 14th birthday. Cross moves up the age category on 1st Sept as the season is building to the National Champs which are in Jan of the following year. As your daughter will be 13 in 2013 (born 2000) she must be a juvenile next year.
Apparently the age's will change at the new year ie 1st Jan, which is the same as other age range changes on the BC race entry pages.
The entry age criteria has now been changed on the BC race entry pages. It was incorrect for next year, it was stating they had to be a year older, BC agreed.