Our club does this too, and as you say it's not ideal. Ice is a massive risk - it's the cause of most Sunday morning accidents that I have witnessed.(not many in total, I should stress!)TrevA wrote: ↑7 Sep 2021, 9:10pm We do start our winter Sunday club rides half an hour later, as a concession to the cold and potential frost/ice, but it actually makes little difference. If it’s cold, it will be cold all day and a couple of hours only makes a couple of degrees difference. If it’s icy, it’s often still icy until after lunch and in mid-winter it’s getting dark at 3.30.
0930 isn't usually a lot warmer than 0900. However, if it's a sunny day, the thaw will at least come earlier in the ride. And most ice removal in the morning is by vehicle tyres, not by the sun (very broad brush statement).
(If we're talking about rider comfort, overcast winter days tend to be nearly as cold at 1pm as 9am. If a wind gets up, it can be worse!)