Many of the newer cycling tops actually have SPF built into the jersey itself. Like many of you, I ride in tank tops quite often, and should probably rethink that situation. If you're not able to find long sleeve jerseys this time of year, they are available, you may have to ask your shop to order. The other option is to wear arm warmers with your short sleeve jersey; there are several options in terms of weight with arm warmers and this should give you another choice.