This may sound like a stupid/overly general question, but for those of you that ride in the rain regularly - do you have any tips as to how to do it successfully?
I find for me it's tough because I am usually too hot to wear any sort of waterproof jacket (even high end "breathable" goretex jackets), and if the temperature is cold enough to wear the jacket, then any more than a light amount of rain will get too cold once the rest of my body (feet, head, hands, lower body) gets drenched. I find that there is a very small sweet spot between the amount of rain and temperature where I am able to have a successful ride in the rain.
I still ride a lot throughout the winter but I'm usually paying close attention to the weather report and am reluctant to ride if there is more than light rain.
Many people overdress and end up sweating, reducing the effectiveness of whatever it is they're wearing. What are you wearing under your jacket? If it's btwn 5-9 degrees and raining, I will wear a jacket over top of a thin, long-sleeved wool layer, OR an undershirt and jersey. If it's colder, I switch to a thicker merino layer, or two thin merino layers, or merino layer under jersey - those all work for me. Add wool socks, bring an extra set of gloves and I'm set.
Cold and dry is easy to dress for. Cold and wet - i.e. btwn 4 and -1 - is the hardest, but if I can keep my feet relatively warm/dry, the top is similar to what I wrote above.
"Be bold, start cold" also applies to rainy days in our neck of the woods, especially since we ride in the protection of thick forests, so wind isn't a factor.