There is no relationship, but, for Class A...
V1 must be ≥ VMCG
VR must be ≥ 1.05 VMCA and
VR must be ≥ V1
If you think about it, none of these imply a relationship between V1 and VMCA unless you can also imply a relationship between VMCA and VMCG. Several threads on Tech Log suggest you can't. There are some dodgy JAA performance questions which imply you can.