First, the obvious stuff – wear sunglasses, apply lots of sunscreen, bring lots of water, etc. (I typically drink 21-25 oz of water per hour – or 1 bottle per hour – during the summer. Thus my standard two-bottle loadout is good for a couple hour ride. Any longer and I have to stop by the convenience store for a refill.) And don’t forget the electrolytes per my previous post either… (See my posts on bottles and the venerable Camelbak packpack for more on that subject)
The less obvious stuff is clothes. Sure, you want to wear shorts and short-sleeve jerseys (I actually prefer sleeveless jerseys, but it’s not necessarily as simple as that.) Some people also swear by special baselayers (i.e. under shirts) that are designed to wick moisture away from your body and up to the top layers. Under Armor and other companies make these, and they’re pretty effective. I still, however, prefer nothing under my jersey when it gets above about 90°F outside. But I am careful to make sure I have lightweight, breathable shorts and jerseys. One of the great things about cycling is the special attention paid to clothing. You can find lots of jerseys that are made of special materials (often jerseys will have multiple different materials) designed to keep you as cool as possible.
The other things to consider are your head and your feet. I recently bought a pair of Mavic shoes that, addition to being very light, are white and largely covered in mesh, instead of the more traditional black, non-breathable leather/vinyl/plastic materials that most shoes are made of. They certainly are cooler on my feet during a hot ride, which is greatly appreciated! (Yes, there are plenty of high-tech socks out there as well. Some of my favorites are the new, ultra-thin breathable fabrics that let the moisture wick away from your feet quickly.)
For your head, I strongly recommend a head band. I use one made by Halo that not only absorbs the sweat, but has a little “rain gutter” on the front that directs any sweat it can’t absorb to the sides of your head. Otherwise it gets on your glasses and then you can’t see! Before I got the Halo band this was a very annoying problem. Now I don’t leave home without my Halo!
Lastly, many people in my area swear by a relatively new product that looks a lot like the arm and leg warmers you wear in the winter months. This product, however, is designed to shield your limbs from the sun and also wick away moisture. Although I’ve never tried them, I see a lot of people riding with them on,so they must work pretty well. (Most peolple’s first reaction upon seeing them is, “why are they wearing arm warmers?!” until I explain.) …Please comment if you’ve tried these, or have any other hot-weather riding tips.
Thanks, and keep cool this summer!