extra body layers with long sleeves (thin thermal tops are great)
light waterproof/windproof jacket
neck scarf / snood (great as sweat bands in the summer and for warmth in the winter)
warm fleece and jacket for the evenings
If you bring your own bike
Make sure you check with your airline what their requirements are before you travel. Pack it carefully, either in a bike box or bag to avoid damage in transit – pipe insulation is perfect to protect the frame. Remember to deflate the tyres, lower the saddle, turn the handle bars in and remove the pedals.
Have your bike serviced before your trip.
Bring with you a spare rear mech hanger, replacement brake pads, chain and inner tubes.