Let's say it's 60f.
- You can bike in cheap non-breathable rainwear - if you bike slowly and casually. You don't need to buy expensive rain gear just to bike a half mile to work.
- I can bike at a medium pace with more expensive, more breathable rainwear.
- To bike all out and be comfortable, I could do it in good wool.

This range changes depending on the temp outside. I can never bike full out in cheap non-breathable rainwear no matter what the temp. With more expensive more breathable rainwear I can bike full out at 40 degrees, medium pace at 60 degrees.

I would basically say that if I had unlimited money here's what I'd do:
- 55 and below: Expensive "breathable" rainwear
- 55-80: Good wool
- 80 and above: Much lighter wool, like wool shorts and t-shirt

I've often pondered whether the best case outfit for 55 and above would be waterproof breathable t-shirt/vest and shorts - enough to keep your core from getting wet, but keep enough air moving in and out via the exposed legs and arms that it doesn't turn into a sauna. But it's just a theory, I haven't tried it.