I rode the zsun social tonight. It perhaps reveals my relative strengths and weaknesses. I rode most of the first lap at the front. It wasn't far off their chaingang pace but it was ok. I rode BH in 8-30 this morning but stuck at ride pace for 10min or so. But 1/2 way through the second lap, 35kn in I really started to struggle being dropped before BH. I rallied riding back through nearly all the group but after the descent again started to struggle and got dropped with 5kn to go. Getting dropped from a group doing 45kmh is just brutal. I pushed on till the end trying to limit my losses. So, it seems my limit is still not much more than an hour and I really do have to work on my stamina. It has been quite a shock moving from riding with a small group of people on bkool to riding on Zwift and finding so many, many fitter and stronger riders.