We no longer operate A, B and C rides as we found 3 categories too restrictive for the number of people we have in the club now. We split into four groups: Black (fastest, hardest effort, approximately 35km/h average on the flat), Blue(30km/h average), Grey (25km/h average) and Green (Slowest, reduced effort, 20km/h average).
I suggest you start with a Green group (there will be a new riders group called every Sunday so join that one) and then move up a grade as appropriate. Joining the 'new riders' ride will also help you learn our group riding skills in a less pressured environment.
There is little point going along with a fast group if you don't think you'll be able to hold on for the duration, especially as we operate a no drop policy on our rides unless otherwise stated at the set off. It is unlikely that other riders in the group will let you fall off the back so if your speed is exceptionally slower than theirs then it is slightly unfair to join their ride.
All of our club rides are operated in the same way, you will find that only the distance and speed varies really.