How do you deal with wet but not cold commutes? (complete newbie here). Do you ride slower to avoid overheating - I assume wet gear isn't great for ventilation
If its a warm wet commute, then no wet weather gear is needed. No point. Lycra dries very quickly, your skin even quicker.. Even a break in the rain on a commute and lycra will be dry in a short while.
Basically this. I throw on a lightweight waterproof jacket, and just ride as normal. The jacket keeps the worst of the rain off, and the rest of my gear dries quickly enough.
A caveat to what
@ianrauk said is that I find that mudguards are an essential for helping keep you comfortable in rain, irrespective of the temperature. If your wheels are throwing up water from the road you'll never dry out until the roads are dry too, plus the roads are generally filthy, especially if it hasn't rained for a while.
On cold commutes, my strategy is exactly the same, except that I'll be wearing more stuff underneath my waterproof jacket, and I'll probably be wearing autumn/spring gear which is thicker and warmer anyway.