I don't think they make a significant benefit for performance or comfort [compared to athletic t shirts] . I just like them and the pockets in the back are very useful for me being a roadie and all. That and the whole lycra shorts \ jersey combo goes well together.
On the cheap you could ditch the tshirts and purchase polyester exercise shirts at target, walmart, etc for around $8-$10. However, they are not cut for a bent over posture. Jerseys are tailored not to show crack.
Last edited by DataJunkie; 07-25-08 at 08:59 AM.
Reason: Clarifying omission to my LBB happy :p