Very late notice, but I'm going to do this tomorrow (with Tom, I think):
Meet Costa 8.30am. Over bridge to Chepstow. Climb up to St Brevels, then on to Coleford. Descent to Monmouth. Flat along the Wye for a coffee at the Old Station (Tinturn); then back up through the forest to Davauden and descent into Cheptow.
This will be fairly 'grippy' (17mph +) but don't let that put you off if you fancy that kind of ride.