When the conditions are changeable, cycling knee warmers are your best friend on the road, offering much needed weather resistance and warmth right when it's needed, and the Castelli NanoFlex Knee Warmer is a great example in this genre.
Offering a wind resistant outer is pretty standard, but for the NanoFlex Knee Warmer, things get really interesting when it starts raining and its water repellent properties come into play. Whilst not full-on rain proof, they will repel showers, which on fast descents or long stretches far from home, can be a really handy feature. Smooth, stretchy and highly breathable, they are great in every ride condition. A silicon top gripper completes the warmer.