Yeah,
Bending springs are meant to be used with un-heated PVC.
If it's a cold day when you're working with it outside, giving the conduit a rub with the palm of your hand can often produce enough warmth to make the bend easier.
I have springs for 16,20,25 and 32mm dia conduit.
Bending the conduit "under" your knee-cap is a pretty common technique here in New Zealand. [Linked Image]