Bottom bearings for headset

[montage]

I have a giant defy 4 frame, for which I have the top half of the headset (putting a china carbon fork in)
For the bottom I need some bearings and a crown cap right?
What measurements do I need to find out what fits? - or if anyone has any suggestions I'm after cheap and cheerful

 

[fossyant]

Might be best with a LBS visit as they can vary.

 

[accountantpete]

Doesn't that bike need a tapered headset?

Have you got a tapered steerer?