I just stop when I need to and take layers or raingear on and off. It means carrying a trunk rack or pannier much of the time. Most of my rides to work start in the cool morning (30-40 degrees) going downhill, but after 4-6 miles I've warmed up and stop to removed something. The big uphill comes at mile 9. In dry weather that's not too cold, I'll start in arm warmers, knee warmers, and long socks so I can adjust while riding.