When it's not major intersection and if the group lead feel it's safe go he will go so all the rest of riders follows. There are quite a few of avid club riders, even attackers/racers, so they pushed the speed up. As I said it's a group ride so riders could take turn draft or take the lead, depending on the ability and road feel at the moment. Ave.speed at about 30km/hr on a group ride is normal. But from 30km/h to 33km/h will be a huge difference. As the higher is the speed, the higher is the wind resistance to overcome, and higher is the output watts yourlegs need to produce.