Not a hard and fast limit. But I think this is just a Good Idea to pay attention to:
if the temperature drops below 50° it is time to wear more than sandals, bike shorts, and a light weight Hawaiian shirt.
Not sayin’ it has to be that way. It’s just a Good Idea.
Postscript: Despite my light attire and the cool temps I still did work up a sweat on the eleven mile, relaxed pace ride.
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