compromises safety as vulnerability is reduced. Professional triathletes competing in these races use "shorty" aerobars mounted on traditional drop handlebars. Triathlon shoes Triathlon shoes are similar to other forms of cycling shoe used in racing, with automatic binding cleats (clipless) that snap the cyclist's feet to the pedals. Tri shoes are often optimised for this approach: they may be padded to allow comfortable use without socks, have holes to allow water from the swim to drain easily, and have only one or two velcro straps for ease of fastening rather than the three straps, laces, or ratcheting buckles found on modern road racing shoes. It is not uncommon for the Velcro straps used to close from the outside of the foot inwards, this non-traditional configuration keeps the opened straps away from the chain and bicycles, preventing the possibility of entangling them if pedaling with unstrapped shoes early or late in the race. Many competitive triathletes choose to leave their shoes clipped onto the pedals for the entire duration of the race in order to save time during transitions. This means the athlete is jumping onto the bicycle with wet, bare feet after the swim, and will pedal up to a reasonable speed, with his or her feet sitting on top of the shoes, before pausing to slip the feet inside the shoes and fasten them. Likewise, the athlete will pull his or her feet out of the shoes while coasting up to the bike-run transition area and run barefoot into the transition corral rather than attempt to run on the awkward cycling cleats. Hydration systems As with everything else, triathletes often strive to make their water bottles as aerodynamic as possible, and often to reduce the need to reach for a water bottle - which may interrupt pedaling and slow the racer down. Triathletes have tried placing water bottles in unusual locations, such as in a bracket behind the saddle, on the theory that the bottles are shielded from the wind by the body. However, a recent wind-tunnel study by Triathlete Magazine discovered that this approach is actually counterproductive because it interrupts the laminar flow of air down the athlete's curved back. A 2003, wind tunnel study by Dan Empfield found that the best configuration was a single water bottle on the bike's downtube (it smoothed airflow to the seat tube and rear wheel). This caused less drag than having