Some positives come out of the cooler weather such as changing colors of foliage, less bugs, and less chance for overheating. However, it takes just a little more preparation. Here's some rules to live by when riding in colder weather.
1. Hydrate - Too many riders take this for granted when dealing with the cold. Insulated bottles work well in the cold too. Drink fluids regularly even if you dont feel like you need to.
2. Layer It Up - Too much clothing and you'll burn up, too little and you'll freeze. Experienced riders know that dressing in several light layers allows you to remove some to regulate temperatures. From inside-out, wear a base layer, middle insulated layer, then a shell on the outside.
3. Stay Dry - Unlike riding in the heat, you do not want to be wet in the cold. Engineered fabrics to wick moisture away from the skin are ideal. Cotton should be avoided.
4. Control The Temps - Starting out with less clothing than you think, with the option to add more later is the best way to go. However, arm warmers and leg/knee warmers offer great flexibility in managing your body temperature. They can easily be rolled down, or stuffed into a jersey pocket as the temperature flucuates. Some offer extra SPF.
5. Cover Your Head - The absolute easiest way to regulate your body heat is to cover your head. Most of your body's heat rises out thru the top of your head. Just like warmers, head gear can easily be removed and stuffed away when you warm up.