Beware of overheating by hanging a light on your jacket
Cycling jackets are often well ventilated, with pit zips, a vent across the shoulders on your back, etc. one thing to beware of – if you hang a light off the loop on your back, there can be enough weight added that he shoulder vent will not open. I discovered the last night on my homeward commute. It was around 14C – balmy for Ontario in mid-January – and I needed every bit of venting in my jacket. Even riding into a strong headwind, I noticed that my venting on my back was not functioning. Ah ha! I had hung a small disc-shaped light off the loop on my back, and its weight was enough to keep the vent closed.