I've got mixed feelings about the sun sleeves. I've got a pair of white pearl izumi sleeves. I would wear them on very long rides, especially when I know it'll be very sunny. I liked the idea of consistent protection, especially on those long rides where I'd need to put another coat of sunscreen mid-ride to ensure good coverage. On very hot, humid days, however, I did feel warmer with them on. So, I'm still kind of in the undecided camp, especially on very hot days. Long rides, very sunny, burt cooler temps - in those conditions I'd be more of a fan. But, try them and see how you feel with them.