Im 39 at the moment and 40 next june.
Am i now racing in the vets as from Jan as its that calender year? or do i race as i am until june and then change category? people keep telling me different things.

Am i now racing in the vets as from Jan as its that calender year?

That’s correct as far as I recall, but some local series may have different rules.
Make the most of it while you’re 40, as the difference between 40 year old vets and 49 year old vets seemed huge to me. 😥

Been interesting in this too, I’ve just found this info from BC

5.9 The following age categories and sub-categories may be
recognised in Federation cyclo-cross events:
Under 12 Up to 31st August in the year of 12th
birthday.

Youth From 1st September in the year of
12th birthday to 31st August in the
year of 16th birthday.

Youth – U14 From 1st September in the year of
12th birthday to 31st August in the
year of 14th birthday.

Junior From 1st September in the year of
16th birthday to 31st August in the
year of 18th birthday.

Senior From 1st September in the year of
18th birthday.

Under-23 From 1st September in the year of
18th birthday to 31st August in the
year of 22nd birthday.

Veteran From 1st September in the year of
40th birthday.

Vet 40 From 1st September in the year of
40th birthday to 31st August in the
year of 45th birthday.

Vet 45 From 1st September in the year of
45th birthday to 31st August in the
year of 50th birthday.

Vet 50 From 1st September in the year of
50th birthday to 31st August in the
year of 55th birthday.

Vet 55 From 1st September in the year of
55th birthday to 31st August in the
year of 60th birthday.

Vet 60 From 1st September in the year of
60th birthday to 31st August in the
year of 65th birthday.

Vet 65 From 1st September in the year of
65th birthday to 31st August in the
year of 70th birthday.

Vet 70+ From 1st September in the year of
70th birthday.

Mountain bike rules differ again

Master From 1st January year of 30th
birthday to 31st December year
of 39th birthday

Veteran From 1st January year of 40th
birthday to 31st December year
of 49th birthday

Grand Veteran From 1st
January year of 50th birthday to
31st December year of 59th
birthday

Super Veteran From 1st
January year of 60th birthday
onwards

Looking at that lot you would be veteran mountain biker but a senior cyclocross rider until 1st sept 2011