There are 2 groups that I know of. One (road) leaves from the traffic circle at the caltex garage in Voelklip at 6am every morning (it's not an official club or anything, just over the years it has sort of become a convention for cyclists on holiday there). The other one is the Hermanus cycle club I think (road & mtb), they leave from the engen garage on the way to Onrus (just opposite hemel-en-aarde village). Not sure of the days/times though.